This document studies module-algebra structures of the quantum universal enveloping algebra Uq(sl(m+1)) on the coordinate algebra of quantum n-dimensional vector spaces Aq(n). The main results are:
1) A complete classification is given of Uq(sl(m+1)) module-algebra structures on Aq(3) when m ≥ 2 and ki acts as an automorphism of Aq(3).
2) All module-algebra structures of Uq(sl(m+1)) on Aq(2) are characterized with the same method.
3) The module-algebra structures of Uq(sl(m+1)) on Aq(n)
To give the complete list of Uq(sl2)-actions of the quantum plane, we first obtain the structure of quantum plane automorphisms. Then we introduce some special symbolic matrices to classify the series of actions using the weights. There are uncountably many isomorphism classes of the symmetries. We give the classical limit of the above actions.
Bound- State Solution of Schrodinger Equation with Hulthen Plus Generalized E...ijrap
We apply an approximation to centrifugal term to find bound state solutions to Schrodinger equation with
Hulthen Plus generalized exponential Coulomb potential Using Nikiforov-Uvarov Method. Using this
method, we obtained the energy-eigen value and the total wave function. We implement C++ algorithm, to
obtained the numerical values of the energy for different quantum state starting from the first excited state
for different values of the screening parameter.
EXACT SOLUTIONS OF SCHRÖDINGER EQUATION WITH SOLVABLE POTENTIALS FOR NON PT/P...ijrap
We have obtained explicitly the exact solutions of the Schrodinger equation with Non PT/PT symmetric
Rosen Morse II, Scarf II and Coulomb potentials. Energy eigenvalues and the corresponding
unnormalized wave functions for these systems for both Non PT and PT symmetric are also obtained using
the Nikiforov-Uvarov (NU) method.
To give the complete list of Uq(sl2)-actions of the quantum plane, we first obtain the structure of quantum plane automorphisms. Then we introduce some special symbolic matrices to classify the series of actions using the weights. There are uncountably many isomorphism classes of the symmetries. We give the classical limit of the above actions.
Bound- State Solution of Schrodinger Equation with Hulthen Plus Generalized E...ijrap
We apply an approximation to centrifugal term to find bound state solutions to Schrodinger equation with
Hulthen Plus generalized exponential Coulomb potential Using Nikiforov-Uvarov Method. Using this
method, we obtained the energy-eigen value and the total wave function. We implement C++ algorithm, to
obtained the numerical values of the energy for different quantum state starting from the first excited state
for different values of the screening parameter.
EXACT SOLUTIONS OF SCHRÖDINGER EQUATION WITH SOLVABLE POTENTIALS FOR NON PT/P...ijrap
We have obtained explicitly the exact solutions of the Schrodinger equation with Non PT/PT symmetric
Rosen Morse II, Scarf II and Coulomb potentials. Energy eigenvalues and the corresponding
unnormalized wave functions for these systems for both Non PT and PT symmetric are also obtained using
the Nikiforov-Uvarov (NU) method.
NITheP UKZN Seminar: Prof. Alexander Gorokhov (Samara State University, Russi...Rene Kotze
NITheP UKZN Seminar: Prof. Alexander Gorokhov (Samara State University, Russia)
TITLE: Dynamical Groups, Coherent States and Some of their Applications in Quantum Optics and Molecular Spectroscopy
Wits Node Seminar: Dr Sunandan Gangopadhyay (NITheP Stellenbosch)
TITLE: Path integral action of a particle in the noncommutative plane and the Aharonov-Bohm effect
Stochastic Gravity in Conformally-flat SpacetimesRene Kotze
The National Institute for Theoretical Physics, and the Mandelstam Institute for Theoretical Physics, School of Physics, would like to invite to its coming talk in the theoretical physics seminar series, entitled:
"Stochastic Gravity in Conformally-flat Spacetimes"
to be presented by Prof. Hing-Tong Cho (Tamkang University, Taiwan)
Abstract: The theory of stochastic gravity takes into account the effects of quantum field fluctuations onto the classical spacetime. The essential physics can be understood from the analogous Brownian motion model. We shall next concentrate on the case with conformally-flat spacetimes. Our main concern is to derive the so-called noise kernels. We shall also describe our on-going program to investigate the Einstein-Langevin equation in these spacetimes.
Dates: Tuesday, 17th February 2015
Venue: The Frank Nabarro lecture theatre, P216
Time: 13.20 - 14.10 - TODAY
Some Common Fixed Point Theorems for Multivalued Mappings in Two Metric SpacesIJMER
In this paper we prove some common fixed point theorems for multivalued mappings in two
complete metric spaces.
AMS Mathematics Subject Classification: 47H10, 54H25
NITheP WITS node Seminar by Dr Dr. Roland Cristopher F. Caballar (NITheP/UKZN)
TITLE: "One-Dimensional Homogeneous Open Quantum Walks"
ABSTRACT: In this talk, we consider a system undergoing an open quantum walk on a one-dimensional lattice. Each jump of the system between adjacent lattice points in a given direction corresponds to a jump operator, with these jump operators either commuting or not commuting. We examine the dynamics of the system undergoing this open quantum walk, in particular deriving analytically the probability distribution of the system, as well as examining numerically the behavior of the probability distribution over long time steps. The resulting distribution is shown to have multiple components, which fall under two general categories, namely normal and solitonic components. The analytic computation of the probability distribution for the system undergoing this open quantum walk allows us to determine at any instant of time the dynamical properties of the system.
Hosoya polynomial, wiener and hyper wiener indices of some regular graphsieijjournal
Let G be a graph. The distance d(u,v) between two vertices u and v of G is equal to the length of a shortest
path that connects u and v. The Wiener index W(G) is the sum of all distances between vertices of G,
whereas the hyper-Wiener index WW(G) is defined as ( ) ( ( ) ( ) ) ( )
2
{u,v} V G
WW G d v,u d v,u .
Î
= + Also, the
Hosoya polynomial was introduced by H. Hosoya and define ( ) ( )
( )
,
{u,v} V G
, . d v u H G x x
Î
= In this
paper, the Hosoya polynomial, Wiener index and Hyper-Wiener index of some regular graphs are
determined.
Hecke Operators on Jacobi Forms of Lattice Index and the Relation to Elliptic...Ali Ajouz
Jacobi forms of lattice index, whose theory can be viewed as extension of the theory of classical Jacobi forms, play an important role in various theories, like the theory of orthogonal modular forms or the theory of vertex operator
algebras. Every Jacobi form of lattice index has a theta expansion which implies, for index of odd rank, a connection to half integral weight modular forms and then via Shimura lifting to modular forms of integral weight, and implies a direct connection to modular forms of integral weight if the rank is
even. The aim of this thesis is to develop a Hecke theory for Jacobi forms of lattice index extending the Hecke theory for the classical Jacobi forms, and to study how the indicated relations to elliptic modular forms behave under Hecke operators. After defining Hecke operators as double coset operators,
we determine their action on the Fourier coefficients of Jacobi forms, and we determine the multiplicative relations satisfied by the Hecke operators, i.e. we study the structural constants of the algebra generated by the Hecke operators. As a consequence we show that the vector space of Jacobi forms
of lattice index has a basis consisting of simultaneous eigenforms for our Hecke operators, and we discover the precise relation between our Hecke algebras and the Hecke algebras for modular forms of integral weight. The
latter supports the expectation that there exist equivariant isomorphisms between spaces of Jacobi forms of lattice index and spaces of integral weight modular forms. We make this precise and prove the existence of such liftings
in certain cases. Moreover, we give further evidence for the existence of such liftings in general by studying numerical examples.
A complete list of Uq(sl2)-module algebra structures on the quantum plane is produced and the (uncountable family of) isomorphism classes of these structures are described. The composition series of representations in question are computed. The classical limits of the Uq(sl2)-module algebra structures are discussed.
This article is interested to a detailed computation of the commutators of the Hopaf
algebra Uq(sl(n)). It can be treated as a second way to computation the brackets
of the Hopf algebra Uq(sl(n)) which could be introducing and understanding the
Uq(sl(n)) for the researchers.
NITheP UKZN Seminar: Prof. Alexander Gorokhov (Samara State University, Russi...Rene Kotze
NITheP UKZN Seminar: Prof. Alexander Gorokhov (Samara State University, Russia)
TITLE: Dynamical Groups, Coherent States and Some of their Applications in Quantum Optics and Molecular Spectroscopy
Wits Node Seminar: Dr Sunandan Gangopadhyay (NITheP Stellenbosch)
TITLE: Path integral action of a particle in the noncommutative plane and the Aharonov-Bohm effect
Stochastic Gravity in Conformally-flat SpacetimesRene Kotze
The National Institute for Theoretical Physics, and the Mandelstam Institute for Theoretical Physics, School of Physics, would like to invite to its coming talk in the theoretical physics seminar series, entitled:
"Stochastic Gravity in Conformally-flat Spacetimes"
to be presented by Prof. Hing-Tong Cho (Tamkang University, Taiwan)
Abstract: The theory of stochastic gravity takes into account the effects of quantum field fluctuations onto the classical spacetime. The essential physics can be understood from the analogous Brownian motion model. We shall next concentrate on the case with conformally-flat spacetimes. Our main concern is to derive the so-called noise kernels. We shall also describe our on-going program to investigate the Einstein-Langevin equation in these spacetimes.
Dates: Tuesday, 17th February 2015
Venue: The Frank Nabarro lecture theatre, P216
Time: 13.20 - 14.10 - TODAY
Some Common Fixed Point Theorems for Multivalued Mappings in Two Metric SpacesIJMER
In this paper we prove some common fixed point theorems for multivalued mappings in two
complete metric spaces.
AMS Mathematics Subject Classification: 47H10, 54H25
NITheP WITS node Seminar by Dr Dr. Roland Cristopher F. Caballar (NITheP/UKZN)
TITLE: "One-Dimensional Homogeneous Open Quantum Walks"
ABSTRACT: In this talk, we consider a system undergoing an open quantum walk on a one-dimensional lattice. Each jump of the system between adjacent lattice points in a given direction corresponds to a jump operator, with these jump operators either commuting or not commuting. We examine the dynamics of the system undergoing this open quantum walk, in particular deriving analytically the probability distribution of the system, as well as examining numerically the behavior of the probability distribution over long time steps. The resulting distribution is shown to have multiple components, which fall under two general categories, namely normal and solitonic components. The analytic computation of the probability distribution for the system undergoing this open quantum walk allows us to determine at any instant of time the dynamical properties of the system.
Hosoya polynomial, wiener and hyper wiener indices of some regular graphsieijjournal
Let G be a graph. The distance d(u,v) between two vertices u and v of G is equal to the length of a shortest
path that connects u and v. The Wiener index W(G) is the sum of all distances between vertices of G,
whereas the hyper-Wiener index WW(G) is defined as ( ) ( ( ) ( ) ) ( )
2
{u,v} V G
WW G d v,u d v,u .
Î
= + Also, the
Hosoya polynomial was introduced by H. Hosoya and define ( ) ( )
( )
,
{u,v} V G
, . d v u H G x x
Î
= In this
paper, the Hosoya polynomial, Wiener index and Hyper-Wiener index of some regular graphs are
determined.
Hecke Operators on Jacobi Forms of Lattice Index and the Relation to Elliptic...Ali Ajouz
Jacobi forms of lattice index, whose theory can be viewed as extension of the theory of classical Jacobi forms, play an important role in various theories, like the theory of orthogonal modular forms or the theory of vertex operator
algebras. Every Jacobi form of lattice index has a theta expansion which implies, for index of odd rank, a connection to half integral weight modular forms and then via Shimura lifting to modular forms of integral weight, and implies a direct connection to modular forms of integral weight if the rank is
even. The aim of this thesis is to develop a Hecke theory for Jacobi forms of lattice index extending the Hecke theory for the classical Jacobi forms, and to study how the indicated relations to elliptic modular forms behave under Hecke operators. After defining Hecke operators as double coset operators,
we determine their action on the Fourier coefficients of Jacobi forms, and we determine the multiplicative relations satisfied by the Hecke operators, i.e. we study the structural constants of the algebra generated by the Hecke operators. As a consequence we show that the vector space of Jacobi forms
of lattice index has a basis consisting of simultaneous eigenforms for our Hecke operators, and we discover the precise relation between our Hecke algebras and the Hecke algebras for modular forms of integral weight. The
latter supports the expectation that there exist equivariant isomorphisms between spaces of Jacobi forms of lattice index and spaces of integral weight modular forms. We make this precise and prove the existence of such liftings
in certain cases. Moreover, we give further evidence for the existence of such liftings in general by studying numerical examples.
A complete list of Uq(sl2)-module algebra structures on the quantum plane is produced and the (uncountable family of) isomorphism classes of these structures are described. The composition series of representations in question are computed. The classical limits of the Uq(sl2)-module algebra structures are discussed.
This article is interested to a detailed computation of the commutators of the Hopaf
algebra Uq(sl(n)). It can be treated as a second way to computation the brackets
of the Hopf algebra Uq(sl(n)) which could be introducing and understanding the
Uq(sl(n)) for the researchers.
This paper reviews the fundamental concepts and
the basic theory of polarization mode dispersion(PMD) in optical
fibers. It introduces a unified notation and methodology to
link the various views and concepts in jones space and strokes
space. The discussion includes the relation between Jones vectors
and Strokes vectors and how they are used in formulating the
jones matrix by the unitary system matrix.
Quantum bialgebras derivable from Uq(sl2) which contain idempotents and von Neumann regular Cartan-like generators are introduced and investigated. Various types of antipodes (invertible and von Neumann regular) on these bialgebras are constructed, which leads to a Hopf algebra structure and a von Neumann-Hopf algebra structure, respectively. For them, explicit forms of some particular R-matrices (also, invertible and von Neumann regular) are presented, and the latter respects the Pierce decomposition.
Code of the Multidimensional Fractional Quasi-Newton Method using Recursive P...mathsjournal
The following paper presents one way to define and classify the fractional quasi-Newton method through a group of fractional matrix operators, as well as a code written in recursive programming to implement this method, which through minor modifications, can be implemented in any fractional fixed-point method that allows solving nonlinear algebraic equation systems.
We introduce a polyadic analog of supersymmetry by considering the polyadization procedure (proposed by the author) applied to the toy model of one-dimensional supersymmetric quantum mechanics. The supercharges are generalized to polyadic ones using the n-ary sigma matrices defined in earlier work. In this way, polyadic analogs of supercharges and Hamiltonians take the cyclic shift block matrix form, and they can describe multidegenerated quantum states in a way that is different from the N-extended and multigraded SQM. While constructing the corresponding supersymmetry as an n-ary Lie superalgebra (n is the arity of the initial associative multiplication), we have found new brackets with a reduced arity of 2<=m<n and a related series of m-ary superalgebras (which is impossible for binary superalgebras). In the case of even reduced arity m we obtain a tower of higher order (as differential operators) even Hamiltonians, while for m odd we get a tower of higher order odd supercharges, and the corresponding algebra consists of the odd sector only.
https://arxiv.org/abs/2406.02188
We generalize σ-matrices to higher arities using the polyadization procedure proposed by the author. We build the nonderived n-ary version of SU(2) using cyclic shift block matrices. We define a new function, the polyadic trace, which has an additivity property analogous to the ordinary trace for block diagonal matrices and which can be used to build the corresponding invariants. The elementary Σ-matrices introduced here play a role similar to ordinary matrix units, and their sums are full Σ-matrices which can be treated as a polyadic analog of σ-matrices. The presentation of n-ary SU(2) in terms of full Σ-matrices is done using the Hadamard product. We then generalize the Pauli group in two ways: for the binary case we introduce the extended phase shifted σ-matrices with multipliers in cyclic groups of order 4q (q>4), and for the polyadic case we construct the correspondent finite n-ary semigroup of phase-shifted elementary Σ-matrices of order 4q(n-1)+1, and the finite n-ary group of phase-shifted full Σ-matrices of order 4q. Finally, we introduce the finite n-ary group of heterogeneous full Σ^het-matrices of order (4q(n-1))^4. Some examples of the lowest arities are presented.
https://arxiv.org/abs/2403.19361. *) https://www.researchgate.net/publication/360882654_Polyadic_Algebraic_Structures, https://iopscience.iop.org/book/978-0-7503-2648-3.
CONTENTS 1. INTRODUCTION 2. PRELIMINARIES 3. POLYADIC SU p2q 4. POLYADIC ANALOG OF SIGMA MATRICES 4.1. Elementary Σ-matrices 4.2. Full Σ-matrices 5. TERNARY SUp2q AND Σ-MATRICES 6. n-ARY SEMIGROUPS AND GROUPS OF Σ-MATRICES 6.1. The Pauli group 6.2. Groups of phase-shifted sigma matrices 6.3. The n-ary semigroup of elementary Σ-matrices 6.4. The n-ary group of full Σ-matrices 7. HETEROGENEOUS FULL Σ-MATRICES REFERENCES
We introduce a new class of division algebras, the hyperpolyadic algebras, which correspond to the binary division algebras R, C, H, O without considering new elements. First, we use the matrix polyadization procedure proposed earlier which increases the dimension of the algebra. The algebras obtained in this way obey binary addition and a nonderived n-ary multiplication and their subalgebras are division n-ary algebras. For each invertible element we define a new norm which is polyadically multiplicative, and the corresponding map is a n-ary homomorphism. We define a polyadic analog of the Cayley-Dickson construction which corresponds to the consequent embedding of monomial matrices from the polyadization procedure. We then obtain another series of n-ary algebras corresponding to the binary division algebras which have a higher dimension, that is proportional to the intermediate arities. Second, a new polyadic product of vectors in any vector space is defined. Endowed with this product the vector space becomes a polyadic algebra which is a division algebra under some invertibility conditions, and its structure constants are computed. Third, we propose a new iterative process ("imaginary tower"), which leads to nonunital nonderived ternary division algebras of half the dimension, which we call "half-quaternions" and "half-octonions". The latter are not subalgebras of the binary division algebras, but subsets only, since they have different arity. Nevertheless, they are actually ternary division algebras, because they allow division, and their nonzero elements are invertible. From the multiplicativity of the introduced "half-quaternion" norm we obtain the ternary analog of the sum of two squares identity. We prove that the unitless ternary division algebra of imaginary "half-octonions" we have introduced is ternary alternative.
https://arxiv.org/abs/2312.01366
https://www.amazon.com/s?k=duplij
https://arxiv.org/abs/2312.01366.
We introduce a new class of division algebras, hyperpolyadic algebras, which correspond to the binary division algebras R, C, H, O without considering new elements. First, we use the proposed earlier matrix polyadization procedure which increases the algebra dimension. The obtained algebras obey the binary addition and nonderived n-ary multiplication and their subalgebras are division n-ary algebras. For each invertible element we define a new norm which is polyadically multiplicative and the corresponding map is n-ary homomorphism. We define a polyadic analog of the Cayley-Dickson construction which corresponds to the consequent embedding of monomial matrices from the polyadization procedure. Then we obtain another series of n-ary algebras corresponding to the binary division algebras which have more dimension, that is proportional to intermediate arities, and they are not isomorphic to those obtained by the previous constructions. Second, we propose a new iterative process (we call it "imaginary tower"), which leads to nonunital nonderived ternary division algebras of half dimension, we call them "half-quaternions" and "half-octonions". The latter are not subalgebras of the binary division algebras, but subsets only, since they have different arity. Nevertheless, they are actually ternary division algebras, because allow division, and their nonzero elements are invertible. From the multiplicativity of the introduced "half-quaternion" norm we obtain the ternary analog of the sum of two squares identity. We prove that the introduced unitless ternary division algebra of imaginary "half-octonions" is ternary alternative.
178 pages, 6 Chapters. DOI: 10.1088/978-0-7503-5281-9. This book presents new and prospective approaches to quantum computing. It introduces the many possibilities to further develop the mathematical methods of quantum computation and its applications to future functioning and operational quantum computers. In this book, various extensions of the qubit concept, starting from obscure qubits, superqubits and other fundamental generalizations, are considered. New gates, known as higher braiding gates, are introduced. These new gates are implemented as an additional stage of computation for topological quantum computations and unconventional computing when computational complexity is affected by its environment. Other generalizations are considered and explained in a widely accessible and easy-to-understand way. Presented in a book for the first time, these new mathematical methods will increase the efficiency and speed of quantum computing.Part of IOP Series in Coherent Sources, Quantum Fundamentals, and Applications. Key features • Provides new mathematical methods for quantum computing. • Presents material in a widely accessible way. • Contains methods for unconventional computing where there is computational complexity. • Provides methods to increase speed and efficiency. For the light paperback version use MyPrint service here: https://iopscience.iop.org/book/mono/978-0-7503-5281-9, also PDF, ePub and Kindle. For the libraries and direct ordering from IOP: https://store.ioppublishing.org/page/detail/Innovative-Quantum-Computing/?K=9780750352796. Amazon ordering: https://www.amazon.de/gp/product/0750352795
Quantum field theory has achieved some extraordinary successes over the past sixty years; however, it retains a set of challenging problems. It is not yet able to describe gravity in a mathematically consistent manner. CP violation remains unexplained. Grand unified theories have been eliminated by experiment, and a viable unification model has yet to replace them. Even the highly successful quantum chromodynamics, despite significant computational achievements, struggles to provide theoretical insight into the low-energy regime of quark physics, where the nature and structure of hadrons are determined. The only proposal for resolving the fine-tuning problem, low-energy supersymmetry, has been eliminated by results from the LHC. Since mathematics is the true and proper language for quantitative physical models, we expect new mathematical constructions to provide insight into physical phenomena and fresh approaches for building physical theories.
https://www.mdpi.com/books/book/6455
We investigate finite field extensions of the unital 3-field, consisting of the unit element alone, and find considerable differences to classical field theory. Furthermore, the structure of their automorphism groups is clarified and the respective subfields are determined. In an attempt to better understand the structure of 3-fields that show up here we look at ways in which new unital 3-fields can be obtained from known ones in terms of product structures, one of them the Cartesian product which has no analogue for binary fields.
https://arxiv.org/abs/2212.08606
Abstract: Algebraic structures in which the property of commutativity is substituted by the me- diality property are introduced. We consider (associative) graded algebras and instead of almost commutativity (generalized commutativity or e-commutativity), we introduce almost mediality (“commutativity-to-mediality” ansatz). Higher graded twisted products and “deforming” brackets (being the medial analog of Lie brackets) are defined. Toyoda’s theorem which connects (universal) medial algebras with abelian algebras is proven for the almost medial graded algebras introduced here. In a similar way we generalize tensor categories and braided tensor categories. A polyadic (non-strict) tensor category has an n-ary tensor product as an additional multiplication with (n-1) associators of the arity (2n-1) satisfying a (n^2-1)-gon relation, which is a polyadic analog of the pentagon axiom. Polyadic monoidal categories may contain several unit objects, and it is also possible that all objects are units. A new kind of polyadic categories (called groupal) is defined: they are close to monoidal categories but may not contain units: instead the querfunctor and (natural) functorial isomorphisms, the quertors, are considered (by analogy with the querelements in n-ary groups). The arity-nonreducible n-ary braiding is introduced and the equation for it is derived, which for n=2 coincides with the Yang–Baxter equation. Then, analogously to the first part of the paper, we introduce “medialing” instead of braiding and construct “medialed” polyadic tensor categories.
In this note we, first, recall that the sets of all representatives of some special ordinary residue classes become (m, n)-rings. Second, we introduce a possible p-adic analog of the residue class modulo a p-adic integer. Then, we find the relations which determine, when the representatives form a (m, n)-ring. At the very short spacetime scales such rings could lead to new symmetries of modern particle models.
Книга «Поэфизика души» представляет собой полное, на момент издания 2022 г., собрание прозаических произведений автора. Как рассказы, так и миниатюры на полстраницы, пронизаны эмоциями и искренними чувствами на грани срыва, что заставляет возвращаться к ним вновь. Буквально каждое слово рисует уникальные картины нетривиальных внутренних миров автора, которые перетекают друг в друга поэтическими образами, воплощенными в прозе. Также включены юмористические путевые заметки о поездке в Китай.
Книга "Поэфизика души", Степан Дуплий – полное собрание прозы 2022, 230 стр. вышла в Ridero: https://ridero.ru/books/poefizika_dushi и Kindle Edition file на Амазоне: https://amazon.com/dp/B0B9Y4X4VJ . "Бумажную" книгу можно заказать на Озоне https://ozon.ru/product/poefizika-dushi-682515885/?sh=XPu-9Sb42Q и на ЛитРес: https://litres.ru/stepan-dupliy/poefizika-dushi-emocionalnaya-proza-kitayskiy-shtrih-punktir . Google books: https://books.google.com/books?id=9w2DEAAAQBAJ .
Книгу можно заказать из-за рубежа на AliExpress: https://aliexpress.com/item/1005004660613179.html .
Книга «Гравитация страсти» представляет собой полное собрание стихотворений автора на момент издания (август, 2022). Стихотворения пронизаны эмоциями и искренними чувствами на грани срыва, что заставляет возвращаться к ним вновь. Буквально каждое слово рисует уникальные картины нетривиальных внутренних миров автора, которые перетекают друг в друга необычными поэтическими образами.
Книга "Гравитация страсти", Степан Дуплий - полное собрание стихотворений 2022, 338 стр. вышла в Ridero: https://ridero.ru/books/gravitaciya_strasti
. Книга в мягкой обложке доступна для заказа на Ozon.ru: https://ozon.ru/product/gravitatsiya-strasti-707068219/?oos_search=false&sh=XPu-9TbW9Q
, на Litres.ru: https://www.litres.ru/stepan-dupliy/gravitaciya-strasti-stihotvoreniya , за рубежом на AliExpress: https://aliexpress.com/item/1005004722134442.html , и в электронном виде Kindle file на Amazon.com: https://amazon.com/dp/B0BDFTT33W .
A generalization of the semisimplicity concept for polyadic algebraic structures is proposed. If semisimple structures can be presented as block diagonal matrices (resulting in the Wedderburn decomposition), general forms of polyadic structures are given by block-shift matrices. We combine these forms to get a general shape of semisimple nonderived polyadic structures (“double” decomposition of two kinds). We then introduce the polyadization concept (a “polyadic constructor”), according to which one can construct a nonderived polyadic algebraic structure of any arity from a given binary structure. The polyadization of supersymmetric structures is also discussed. The “deformation” by shifts of operations on the direct power of binary structures is defined and used to obtain a nonderived polyadic multiplication. Illustrative concrete examples for the new constructions are given.
A generalization of the semisimplicity concept for polyadic algebraic structures is proposed. If semisimple structures can be presented in the block-diagonal matrix form (Wedderburn decomposition), a general form of polyadic structures is given by block-shift matrices. We combine these forms in a special way to get a general shape of semisimple nonderived polyadic structures. We then introduce the polyadization concept (a "polyadic constructor") according to which one can construct a nonderived polyadic algebraic structure of any arity from a given binary structure. The polyadization of supersymmetric structures is also discussed. The "deformation" by shifts of operations on the direct power of binary structures is defined and used to obtain a nonderived polyadic multiplication. Illustrative concrete examples for the new constructions are given.
We generalize the Grothendieck construction of the completion group for a monoid (being the starting point of the algebraic $K$-theory) to the polyadic case, when an initial semigroup is $m$-ary and the corresponding final class group $K_{0}$ can be $n$-ary. As opposed to the binary case: 1) there can be different polyadic direct products which can be built from one polyadic semigroup; 2) the final arity $n$ of the class groups can be different from the arity $m$ of initial semigroup; 3) commutative initial $m$-ary semigroups can lead to noncommutative class $n$-ary groups; 4) the identity is not necessary for initial $m$-ary semigroup to obtain the class $n$-ary group, which in its turn can contain no identity at all. The presented numerical examples show that the properties of the polyadic completion groups are considerably nontrivial and have more complicated structure than in the binary case.
In book: S. Duplij, "Polyadic Algebraic Structures", 2022, IOP Publishing (Bristol), Section 1.5. See https://iopscience.iop.org/book/978-0-7503-2648-3
https://arxiv.org/abs/2206.14840
The book is devoted to the thorough study of polyadic (higher arity) algebraic structures, which has a long history, starting from 19th century. The main idea was to take a single set, closed under one binary operation, and to 'generalize' it by increasing the arity of the operation, called a polyadic operation. Until now, a general approach to polyadic concrete many-set algebraic structures was absent. We propose to investigate algebraic structures in the 'concrete way' and provide consequent 'polyadization' of each operation, starting from group-like structures and finishing with the Hopf algebra structures. Polyadic analogs of homomorphisms which change arity, heteromorphisms, are introduced and applied for constructing unusual representations, multiactions, matrix representations and polyadic analogs of direct product. We provide the polyadic generalization of the Yang–Baxter equation, find its constant solutions, and introduce polyadic tensor categories.
Suitable for university students of advanced level algebra courses and mathematical physics courses.
Key features
• Provides a general, unified approach
• Widens readers perspective of the possibilities to develop standard algebraic structures
• Provides the new kind of homomorphisms changing the arity, heteromorphisms, are introduced and applied for construction of new representations, multiactions and matrix representations
• Presents applications of 'polyadization' approach to concrete algebraic structures
We propose a generalization of the external direct product concept to polyadic algebraic structures which introduces novel properties in two ways: the arity of the product can differ from that of the constituents, and the elements from different multipliers can be “entangled” such that the product is no longer componentwise. The main property which we want to preserve is associativity, which is gained by using the associativity quiver technique, which was provided previously. For polyadic semigroups and groups we introduce two external products: (1) the iterated direct product, which is componentwise but can have an arity that is different from the multipliers and (2) the hetero product (power), which is noncomponentwise and constructed by analogy with the heteromorphism concept introduced earlier. We show in which cases the product of polyadic groups can itself be a polyadic group. In the same way, the external product of polyadic rings and fields is generalized. The most exotic case is the external product of polyadic fields, which can be a polyadic field (as opposed to the binary fields), in which all multipliers are zeroless fields. Many illustrative concrete examples are presented. Thу proposed construction can lead to a new category of polyadic fields.
https://arxiv.org/abs/2201.08479
We propose a generalization of the external direct product concept to polyadic algebraic structures which introduces novel properties in two ways: the arity of the product can differ from that of the constituents, and the elements from different multipliers can be "entangled" such that the product is no longer componentwise. The main property which we want to preserve is associativity, which is gained by using the associativity quiver technique provided earlier. For polyadic semigroups and groups we introduce two external products: 1) the iterated direct product which is componentwise, but can have arity different from the multipliers; 2) the hetero product (power) which is noncomponentwise and constructed by analogy with the heteromorphism concept introduced earlier. It is shown in which cases the product of polyadic groups can itself be a polyadic group. In the same way the external product of polyadic rings and fields is generalized. The most exotic case is the external product of polyadic fields, which can be a polyadic field (as opposed to the binary fields), when all multipliers are zeroless fields, which can lead to a new category of polyadic fields. Many illustrative concrete examples are presented.
A general mechanism for "breaking" commutativity in algebras is proposed: if the underlying set is taken to be not a crisp set, but rather an obscure/ fuzzy set, the membership function, reflecting the degree of truth that an element belongs to the set, can be incorporated into the commutation relations. The special "deformations" of commutativity and ?-commutativity are introduced in such a way that equal degrees of truth result in the "nondeformed" case. We also sketch how to "deform" ?-Lie algebras and Weyl algebras. Further, the above constructions are extended to n-ary algebras for which the projective representations and ?-commutativity are studied.
We generalize the regularity concept for semigroups in two ways simultaneously: to higher regularity and to higher arity. We show that the one-relational and multi-relational formulations of higher regularity do not coincide, and each element has several inverses. The higher idempotents are introduced, and their commutation leads to unique inverses in the multi-relational formulation, and then further to the higher inverse semigroups. For polyadic semigroups we introduce several types of higher regularity which satisfy the arity invariance principle as introduced: the expressions should not depend of the numerical arity values, which allows us to provide natural and correct binary limits. In the first definition no idempotents can be defined, analogously to the binary semigroups, and therefore the uniqueness of inverses can be governed by shifts. In the second definition called sandwich higher regularity, we are able to introduce the higher polyadic idempotents, but their commutation does not provide uniqueness of inverses, because of the middle terms in the higher polyadic regularity conditions. Finally, we introduce the sandwich higher polyadic regularity with generalized idempotents.
In this note we generalize the regularity concept for semigroups in two ways simul- taneously: to higher regularity and to higher arity. We show that the one-relational and multi-relational formulations of higher regularity do not coincide, and each element has several inverses. The higher idempotents are introduced, and their commutation leads to unique inverses in the multi-relational formulation, and then further to the higher inverse semigroups. For polyadic semigroups we introduce several types of higher regularity which satisfy the arity invariance principle as introduced: the expressions should not depend of the numerical arity values, which allows us to provide natural and correct binary limits. In the first definition no idempotents can be defined, analogously to the binary semigroups, and therefore the uniqueness of inverses can be governed by shifts. In the second definition called sandwich higher regularity, we are able to introduce the higher polyadic idempotents, but their commutation does not provide uniqueness of inverses, because of the middle terms in the higher polyadic regularity conditions.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
S. Duplij, Y. Hong, F. Li. Uq(sl(m+1))-module algebra structures on the coordinate algebra of a quantum vector space
1. Journal of Lie Theory
Volume 25 (2015) 327–361
c 2015 Heldermann Verlag
Uq(sl(m + 1))-Module Algebra Structures
on the Coordinate Algebra of a Quantum Vector Space
Steven Duplij∗
, Yanyong Hong, and Fang Li†
Communicated by K. Schm¨udgen
Abstract. In this paper, the module-algebra structures of Uq(sl(m + 1)) =
H(ei, fi, k±1
i )1≤i≤m on the coordinate algebra of quantum vector spaces are
studied. We denote the coordinate algebra of quantum n-dimensional vector
space by Aq(n). As our main result, first, we give a complete classification of
module-algebra structures of Uq(sl(m + 1)) on Aq(3) when ki ∈ Aut L(Aq(3))
as actions on Aq(3) for i = 1, · · · , m and m ≥ 2 and with the same method, on
Aq(2), all module-algebra structures of Uq(sl(m + 1)) are characterized. Lastly,
the module-algebra structures of Uq(sl(m + 1)) on Aq(n) are obtained for any
n ≥ 4.
Mathematics Subject Classification 2010: 81R50, 16T20, 17B37, 20G42, 16S40.
Key Words and Phrases: Quantum enveloping algebra, coordinate algebra of
quantum vector space, Hopf action, module algebra, weight.
1. Introduction
Quantum groups were introduced independently by Drinfeld in [7] and Jimbo in
[16] which opened the floodgates for applications of Hopf algebras to physics,
invariant theory for knots and links, and representations closely connected to Lie
theory. Some basic references for quantum groups are [20] and [12]. Moreover,
the actions of Hopf algebras [21] and their generalizations (see, e.g., [6]) play an
important role in quantum group theory [18, 19] and in its various applications
in physics [4]. However, it was long believed that the quantum plane [20] admits
only one special symmetry [22] inspired by the action of Uq(sl(2)) (in other words
the Uq(sl(2))-module algebra structure [18]). In [15], the coordinate algebra of
quantum n-dimensional vector space is equipped with a special Uq(sl(m + 1))-
module algebra structure via a certain q-differential operator realization. Then it
was shown [8], that the Uq(sl(2))-module algebra structure on the quantum plane
∗
This author was supported by the Alexander von Humbodt Foundation
†
The second and third authors were supported by the National Natural Science Foundation
of China, Projects No.11271318, No.11171296 and No. J1210038, and the Specialized Research
Fund for the Doctoral Program of Higher Education of China (No. 20110101110010), the Zhejiang
Provincial Natural Science Foundation of China (No.LZ13A010001), and the Scientific Research
Foundation of Zhejiang Agriculture and Forestry University (No.2013FR081)
ISSN 0949–5932 / $2.50 c Heldermann Verlag
2. 328 Duplij, Hong, Li
is much richer and consists of 8 nonisomorphic cases [8, 9]. The full classification
was given in terms of a so-called weight which was introduced for this purpose. Its
introduction follows from the general form of an automorphism of the quantum
plane [1]. Some properties of the actions of commutative Hopf algebras on quantum
polynomials were studied in [2, 3]. In addition, there are also many papers studying
Hopf algebras acting on some special algebras, for example, commutative domains,
fields, filtered regular algebras and so on, see [5], [10] and [11].
Following [12], we consider here the actions of the quantum universal en-
veloping algebra Uq(sl(m+1)) on the coordinate algebra of quantum n-dimensional
vector space Aq(n). We use the method of weights [8, 9] to classify some actions
in terms of action matrices which are introduced. We then present the Dynkin
diagrams for the actions thus obtained and find their classical limit. A special
case discussed in this paper was included in [15].
This work is organized as follows. In Section 2, we give the necessary
preliminary information and notation, as well as proving an important lemma
about actions on generators and any elements of Aq(n) . In Section 3, we study
Uq(sl(2))-module algebra structures on Aq(n) using the method of weights [8, 9].
The 0-th homogeneous component and 1-st homogeneous component of the action
matrix are presented. In Section 4, we study the concrete actions of Uq(sl(2))
on Aq(3) and characterize all module algebra structures of Uq(sl(3)) on Aq(3)
which make some preparations on the classification of module algebra structures
of Uq(sl(m + 1)) on Aq(3). In Section 5, with the results of Section 4, all module-
algebra structures of Uq(sl(m + 1)) on Aq(3) when m ≥ 2 are presented. And,
with the same method, all module-algebra structures of Uq(sl(m+1)) on Aq(2) are
given. Section 6 is devoted to study the module-algebra structures of Uq(sl(m+1))
on Aq(n) for n ≥ 4.
In this paper, all algebras, modules and vector spaces are over the field C
of complex numbers.
2. Preliminaries
Let H be a Hopf algebra whose comultiplication is ∆, counit is ε and antipode is
S and let A be a unital algebra with unit 1. We use the Sweedler notation, such
that ∆(h) = i hi ⊗ hi .
Definition 2.1. By a structure of an H -module algebra on A, we mean a
homomorphism π : H → EndCA such that:
(1) π(h)(ab) = i π(hi)(a)π(hi )(b) for all h ∈ H , a, b ∈ A,
(2) π(h)(1) = ε(h)1 for all h ∈ H .
The structures π1 , π2 are said to be isomorphic, if there exists an automor-
phism ψ of A such that ψπ1(h)ψ−1
= π2(h) for all h ∈ H .
Throughout this paper, we assume that q ∈ C{0} and q is not a root of
unity. We use the q-integers which were introduced by Heine [14] and are called
3. Duplij, Hong, Li 329
the Heine numbers or q-deformed numbers [17] (for any integer n > 0)
(n)q =
qn
− 1
q − 1
= 1 + q + · · · + qn−1
.
First, we will introduce the definition of Uq(sl(m + 1)).
Definition 2.2. The quantum universal enveloping algebra Uq(sl(m+1)) (m ≥
1) as the algebra is generated by (ei, fi, ki, k−1
i )1≤i≤m with the relations
kik−1
i = k−1
i ki = 1, kikj = kjki, (2.1)
kiejk−1
i = qaij
ej, kifjk−1
i = q−aij
fj, (2.2)
[ei, fj] = δij
ki − k−1
i
q − q−1
, (2.3)
eiej = ejei and fifj = fjfi, if aij = 0, (2.4)
if aij = −1,
e2
i ej − (q + q−1
)eiejei + eje2
i = 0, (2.5)
f2
i fj − (q + q−1
)fifjfi + fjf2
i = 0, (2.6)
where for any i, j ∈ {1, 2, · · · , m}, aii = 2 and aij = 0, if |i − j| > 1; aij = −1,
if |i − j| = 1.
The standard Hopf algebra structure on Uq(sl(m + 1)) is determined by
∆(ei) = 1 ⊗ ei + ei ⊗ ki, (2.7)
∆(fi) = k−1
i ⊗ fi + fi ⊗ 1, (2.8)
∆(ki) = ki ⊗ ki, ∆(k−1
i ) = k−1
i ⊗ k−1
i , (2.9)
ε(ki) = ε(k−1
i ) = 1, (2.10)
ε(ei) = ε(fi) = 0, (2.11)
S(ei) = −eik−1
i , S(fi) = −kifi, (2.12)
S(ki) = k−1
i , S(k−1
i ) = ki, (2.13)
for i ∈ {1, 2, · · · , m}. We will use the notation Uq(sl(m+1)) = H(ei, fi, k±1
i )1≤i≤m .
Let us introduce the definition of the coordinate algebra of quantum n-
dimensional vector space (see [13, 2]).
Definition 2.3. The coordinate algebra of quantum n-dimensional vector space,
denoted by Aq(n), is a unital algebra generated by n generators xi for i ∈
{1, · · · , n} satisfying the relations
xixj = qxjxi for any i > j. (2.14)
The coordinate algebra of quantum n-dimensional vector space Aq(n) is
also called a quantum n-space. If n = 2, Aq(2) is also called a quantum plane
4. 330 Duplij, Hong, Li
(see [18]). In this case, Duplij and Sinel’shchikov studied the classification of
Uq(sl(2))-module algebra structures on Aq(2) in [8].
Next, we consider the automorphisms of Aq(n). Obviously, ϕ : Aq(n) →
Aq(n) is an automorphism defined as follows:
ϕ : xi → αixi,
with αi ∈ C {0} for i ∈ {1, · · · , n}. In addition, all such automorphisms form
a subgroup of the automorphism group of Aq(n). We denote this subgroup by
Aut L(Aq(n)). It should be pointed out that there are other automorphisms of
Aq(3). For example, σ : Aq(3) → Aq(3) given by
σ(x1) = α1x1, σ(x2) = α2x2 + βx1x3, σ(x3) = α3x3,
with β and αi ∈ C{0} for i ∈ {1, 2, 3} is an automorphism of Aq(3). Throughout
this paper, we restrict the actions of ki in Uq(sl(m+1)) on Aq(n) to Aut L(Aq(n))
for all m and n.
Finally, we present a lemma which will be useful for checking the module-
algebra structures of Uq(sl(m + 1)) on Aq(n).
Lemma 2.4. Given the module-algebra actions of the generators ki , ei , fi of
Uq(sl(m + 1)) on Aq(n) for i ∈ {1, · · · , m}, if an element in the ideal formed
from the relations (2.1)-(2.6) of Uq(sl(m + 1)) acting on the generators xi of
Aq(n) produces zero for i ∈ {1, · · · , n}, then this element acting on any v ∈ Aq(n)
produces zero.
Proof. Here, we only prove that, if
e2
i ei+1(x) − (q + q−1
)eiei+1ei(x) + ei+1e2
i (x) = 0 and
e2
i ei+1(y) − (q + q−1
)eiei+1ei(y) + ei+1e2
i (y) = 0, then
e2
i ei+1(xy) − (q + q−1
)eiei+1ei(xy) + ei+1e2
i (xy) = 0 where
x, y are both generators of Aq(n). The other relations can be proved similarly.
e2
i ei+1(xy) − (q + q−1
)eiei+1ei(xy) + ei+1e2
i (xy)
= e2
i (xei+1(y) + ei+1(x)ki+1(y)) − (q + q−1
)eiei+1(xei(y) + ei(x)ki(y))
+ei+1ei(xei(y) + ei(x)ki(y))
= ei(xeiei+1(y) + ei(x)kiei+1(y) + ei+1(x)eiki+1(y) + eiei+1(x)kiki+1(y))
−(q + q−1
)ei(xei+1ei(y) + ei+1(x)ki+1ei(y) + ei(x)ei+1ki(y) + ei+1ei(x)
·ki+1ki(y)) + ei+1(xe2
i (y) + ei(x)kiei(y) + ei(x)eiki(y) + e2
i (x)k2
i (y))
= (xe2
i ei+1(y) − (q + q−1
)xeiei+1ei(y) + xei+1e2
i (y)) + (e2
i ei+1(x) − (q + q−1
)
·eiejei(x) + eje2
i (x))k2
i ki+1(y) + (ei(x)kieiei+1(y) + ei(x)eikiei+1(y)
5. Duplij, Hong, Li 331
−(q + q−1
)ei(x)eiei+1ki(y)) + (e2
i (x)k2
i ei+1(y) − (q + q−1
)e2
i (x)
·kiei+1ki(y) + e2
i (x)ei+1k2
i (y)) + (ei+1(x)e2
i ki+1(y) − (q + q−1
)ei+1(x)
·eiki+1ei(y) + ei+1(x)ki+1e2
i (y)) + (eiei+1(x)kieiki+1(y) + eiei+1(x)
·eikiki+1(y) − (q + q−1
)eiei+1(x)kiki+1ei(y)) + (−(q + q−1
)ei+1ei(x)
·eiki+1ki(y) + ei+1ei(x)ki+1kiei(y) + ei+1ei(x)ki+1eiki(y))
+(−(q + q−1
)ei(x)kiei+1ei(y) + ei(x)ei+1kiei(y) + ei(x)ei+1eiki(y))
= 0.
Thus, the lemma holds.
Therefore, by Lemma 2.4, in checking whether the relations of Uq(sl(m+1)),
acting on any v ∈ Aq(n), produce zero, we only need to check whether they produce
zero when acting on the generators x1 , · · · , xn .
3. Properties of Uq(sl(2))-module algebras on Aq(n)
In this section, let us assume that Uq(sl(2)) is generated by k, e, f . Then, we will
study the module-algebra structures of Uq(sl(2)) on Aq(n) when k ∈ Aut L(Aq(n))
and n ≥ 3.
By the definition of module algebra, it is easy to see that any action of
Uq(sl(2)) on Aq(n) is determined by the following 3 × n matrix with entries from
Aq(n):
M
def
=
k(x1) k(x2) · · · k(xn)
e(x1) e(x2) · · · e(xn)
f(x1) f(x2) · · · f(xn)
, (3.15)
which is called the action matrix (see [8]). Given a Uq(sl(2))-module algebra
structure on Aq(n), obviously, the action of k determines an automorphism of
Aq(n). Therefore, by the assumption k ∈ Aut L(Aq(n)), we can set
Mk
def
= k(x1) k(x2) · · · k(xn) = α1x1 α2x2 · · · αnxn ,
where αi for i ∈ {1, · · · , n} are non-zero complex numbers. So, every monomial
xm1
1 xm2
2 · · · xmn
n ∈ Aq(n) is an eigenvector for k and the associated eigenvalue
αm1
1 αm2
2 · · · αmn
n is called the weight of this monomial, which will be written as
wt(xm1
1 xm2
2 · · · xmn
n ) = αm1
1 αm2
2 · · · αmn
n .
Set
Mef
def
=
e(x1) e(x2) · · · e(xn)
f(x1) f(x2) · · · f(xn)
. (3.16)
Then, we have
wt(Mef )
def
=
wt(e(x1)) wt(e(x2)) · · · wt(e(xn))
wt(f(x1)) wt(f(x2)) · · · wt(f(xn))
q2
α1 q2
α2 · · · q2
αn
q−2
α1 q−2
α2 · · · q−2
αn
,
6. 332 Duplij, Hong, Li
where the relation A = (aij) B = (bij) means that for every pair of indices i, j
such that both aij and bij are nonzero, one has aij = bij .
In the following, we denote the i-th homogeneous component of M , whose
elements are just the i-th homogeneous components of the corresponding entries
of M , by (M)i . Set
(M)0 =
0 0 · · · 0
a1 a2 · · · an
b1 b2 · · · bn
0
.
Then, we obtain
wt((M)0)
0 0 · · · 0
q2
α1 q2
α2 · · · q2
αn
q−2
α1 q−2
α2 · · · q−2
αn
0
(3.17)
0 0 · · · 0
1 1 · · · 1
1 1 · · · 1
0
.
An application of e and f to (2.14) gives the following equalities
xie(xj) − qαie(xj)xi = qxje(xi) − αje(xi)xj for i > j, (3.18)
f(xi)xj − qα−1
j xjf(xi) = qf(xj)xi − α−1
i xif(xj) for i > j. (3.19)
After projecting the equalities above to (Aq(n))1 , we obtain
aj(1 − qαi)xi = ai(q − αj)xj for i > j;
bi(1 − qα−1
j )xj = bj(q − α−1
i )xi for i > j.
Therefore, for i > j, we obtain
aj = 0 ⇒ αi = q−1
, ai = 0 ⇒ αj = q, (3.20)
bi = 0 ⇒ αj = q, bj = 0 ⇒ αi = q−1
. (3.21)
Then, we have for any j ∈ {1, · · · , n},
aj = 0 ⇒ αi = q−1
for ∀ i > j, αi = q for ∀ i < j, (3.22)
bj = 0 ⇒ αi = q−1
for ∀ i > j, αi = q for ∀ i < j. (3.23)
By (3.17) and using the above equalities, we get
aj = 0 ⇒ α1 = q, · · · , αj−1 = q, αj = q−2
, αj+1 = q−1
, · · · , αn = q−1
,
bj = 0 ⇒ α1 = q, · · · , αj−1 = q, αj = q2
, αj+1 = q−1
, · · · , αn = q−1
.
So, there are 2n + 1 cases for 0-th homogeneous component of the action matrix
as follows: aj = 0, ai = 0 for i = j and all bi = 0 for any j ∈ {1, · · · , n}; bj = 0,
7. Duplij, Hong, Li 333
bi = 0 for i = j and all ai = 0 for any j ∈ {1, · · · , n}; aj = 0 and bj = 0 for any
j ∈ {1, · · · , n}.
For the 1-st homogeneous component, since wt(e(xi)) = q2
wt(xi) = wt(xi),
we have (e(xi))1 = s=i cisxs for some cis ∈ C. Similarly, we set (f(xi))1 =
s=i disxs for some dis ∈ C.
After projecting Equations (3.18)-(3.19) to (Aq(n))2 , we can obtain, for any
i > j,
s=j
s<i
(q − qαi)cjsxsxi + (1 − qαi)cjix2
i +
s>i
(1 − q2
αi)cjsxixs =
s<j
(q2
− αj)cisxsxj + (q − αj)cijx2
j +
s=i
s>j
(q − qαj)cisxjxs,
s<j
(1 − q2
α−1
j )disxsxj + (1 − qα−1
j )dijx2
j +
s>j
s=i
(q − qα−1
j )disxjxs =
s<i
s=j
(q − qα−1
i )djsxsxi + (q − α−1
i )djix2
i +
s>i
(q2
− α−1
i )djsxixs.
Therefore, we have
cjs = 0 (s < i, s = j) ⇒ αi = 1, cjs = 0 for all s ≥ i,
cji = 0 ⇒ αi = q−1
, cjs = 0 for any s = i,
cjs = 0 (s > i) ⇒ αi = q−2
, cjs = 0 for all s ≤ i,
cis = 0 (s < j) ⇒ αj = q2
, cis = 0 for all s ≥ j,
cij = 0 ⇒ αj = q, cis = 0 for all s = j,
cis = 0 (s > j, s = i) ⇒ αj = 1, cis = 0 for all s ≤ j,
dis = 0 (s < j) ⇒ αj = q2
, dis = 0 for all s > j,
dij = 0 ⇒ αj = q, dis = 0 for all s = j,
dis = 0 (s > j, s = i) ⇒ αj = 1, dis = 0 for all s ≤ j,
djs = 0 (s < i, s = j) ⇒ αi = 1, djs = 0 for all s ≥ i,
dji = 0 ⇒ αi = q−1
, djs = 0 for all s = i,
djs = 0 (s > i) ⇒ αi = q−2
, djs = 0 for all s ≤ i.
Therefore, we have for any j ∈ {1, · · · , n},
cjs = 0 (s > j) ⇒ α1 = 1, · · · , αj−1 = 1, αj+1 = q−2
, · · · ,
αs−1 = q−2
, αs = q−1
, αs+1 = 1, · · · , αn = 1,
cjs = 0 (s < j) ⇒ α1 = 1, · · · , αs−1 = 1, αs = q, αs+1 = q2
, · · · ,
αj−1 = q2
, αj+1 = 1, · · · , αn = 1,
djs = 0 (s > j) ⇒ α1 = 1, · · · , αj−1 = 1, αj+1 = q−2
, · · · ,
αs−1 = q−2
, αs = q−1
, αs+1 = 1, · · · , αn = 1,
djs = 0 (s < j) ⇒ α1 = 1, · · · , αs−1 = 1, αs = q, αs+1 = q2
, · · · ,
αj−1 = q2
, αj+1 = 1, · · · , αn = 1.
8. 334 Duplij, Hong, Li
Since wt((Mef )1) =
q2
α1 q2
α2 · · · q2
αn
q−2
α1 q−2
α2 · · · q−2
αn 1
, we obtain for any
j ∈ {1, · · · , n},
cjs = 0 (s > j) ⇒ α1 = 1, · · · , αj−1 = 1, αj = q−3
, αj+1 = q−2
, · · · ,
αs−1 = q−2
, αs = q−1
, αs+1 = 1, · · · , αn = 1,
cjs = 0 (s < j) ⇒ α1 = 1, · · · , αs−1 = 1, αs = q, αs+1 = q2
, · · · ,
αj−1 = q2
, αj = q−1
, αj+1 = 1, · · · , αn = 1,
djs = 0 (s > j) ⇒ α1 = 1, · · · , αj−1 = 1, αj = q, αj+1 = q−2
, · · · ,
αs−1 = q−2
, αs = q−1
, αs+1 = 1, · · · , αn = 1,
djs = 0 (s < j) ⇒ α1 = 1, · · · , αs−1 = 1, αs = q, αs+1 = q2
, · · · ,
αj−1 = q2
, αj = q3
, αj+1 = 1, · · · , αn = 1.
By the above discussion, we have only the following possibilities for the 1-st
homogeneous component: cij = 0 for some i = j, other cst equal to zero and all
dst = 0; dij = 0 for some i = j, other dst equal to zero and all cst = 0; cj+1,j = 0,
dj,j+1 = 0 for some j ∈ {1, · · · , n}.
Obviously, if both the 0-th homogeneous component and the 1-st homoge-
neous component of Mef are nonzero, there are no possibilities except when n = 3.
For n = 3, there are only two possibilities (a2 , d13 , b2 , c31 ∈ C{0}):
0 a2 0
0 0 0 0
,
0 0 0
d13 0 0 1
⇒ α1 = q, α2 = q−2
, α3 = q−1
, (3.24)
0 0 0
0 b2 0 0
,
0 0 c31
0 0 0 1
⇒ α1 = q, α2 = q2
, α3 = q−1
. (3.25)
Moreover, there are no possibilities when the 0-th homogeneous component
of Mef is 0 and the 1-st homogeneous component of Mef have only one nonzero
position. The reasons are the same as those in [8].
Therefore, by the above discussion, we can obtain the following theorem.
Theorem 3.1. Given a module algebra structure of Uq(sl(2)) on Aq(n). The 0-
th homogeneous component and 1-st homogeneous component of the action matrix
must be one of the following cases:
Case (3.24), Case (3.25) when n = 3,
0 0 · · · ai · · · 0
0 0 · · · 0 · · · 0 0
,
0 0 · · · 0
0 0 · · · 0 1
, ai = 0 for any i ∈ {1, · · · n},
0 0 · · · 0 · · · 0
0 0 · · · bi · · · 0 0
,
0 0 · · · 0
0 0 · · · 0 1
, bi = 0 for any i ∈ {1, · · · n},
0 0 · · · 0
0 0 · · · 0 0
,
0 0 · · · 0 cj+1,j · · · 0
0 0 · · · dj,j+1 0 · · · 0 1
, cj+1,j , dj,j+1 = 0 for
any j ∈ {1, · · · , n −1},
0 0 · · · 0
0 0 · · · 0 0
,
0 0 · · · 0
0 0 · · · 0 1
for any n ≥ 3.
9. Duplij, Hong, Li 335
4. General structure of Uq(sl(m + 1))-module algebras on Aq(3)
In this section, we study the concrete actions of Uq(sl(2)) on Aq(3) and module
algebra structures of Uq(sl(3)) on Aq(3) which make some preparations on the
classification of module algebra structures of Uq(sl(m + 1)) on Aq(3) for m ≥ 2.
By Theorem 3.1, we only need to consider 11 possibilities
0 0 0
0 0 0 0
,
0 0 0
0 0 0 1
,
a1 0 0
0 0 0 0
,
0 0 0
0 0 0 1
,
0 0 0
0 0 b3 0
,
0 0 0
0 0 0 1
,
0 0 0
0 0 0 0
,
0 c21 0
d12 0 0 1
,
0 0 0
0 0 0 0
,
0 0 c32
0 d23 0 1
,
0 a2 0
0 0 0 0
,
0 0 0
0 0 0 1
,
0 a2 0
0 0 0 0
,
0 0 0
d13 0 0 1
,
0 0 0
0 b2 0 0
,
0 0 0
0 0 0 1
,
0 0 0
0 b2 0 0
,
0 0 c31
0 0 0 1
,
0 0 a3
0 0 0 0
,
0 0 0
0 0 0 1
,
0 0 0
b1 0 0 0
,
0 0 0
0 0 0 1
where ai = 0, bi = 0 for i = 1, 2, 3, and c21 , d12 ,
c32 , d23 , d13 , c31 are not zero.
For convenience, we denote these 11 kinds of cases in the above order by
(∗1), · · · , (∗11) respectively.
Lemma 4.1. For Case (∗1), all Uq(sl(2))-module algebra structures on Aq(3)
are as follows
k(x1) = ±x1, k(x2) = ±x2, k(x3) = ±x3, (4.26)
e(x1) = e(x2) = e(x3) = f(x1) = f(x2) = f(x3) = 0. (4.27)
Proof. The proof is similar to that in Theorem 4.2 in [8].
Lemma 4.2. For Case (∗2), all Uq(sl(2))-module algebra structures on Aq(3)
are
k(x1) = q−2
x1, k(x2) = q−1
x2, k(x3) = q−1
x3, (4.28)
e(x1) = a1, e(x2) = 0, e(x3) = 0, (4.29)
f(x1) = −qa−1
1 x2
1, (4.30)
f(x2) = −qa−1
1 x1x2 + ξ1x2x2
3 + ξ2x3
2 + ξ3x3
3, (4.31)
f(x3) = −qa−1
1 x1x3 + ξ4x2x2
3 + (1 + q + q2
)ξ2x2
2x3 − q−1
ξ1x3
3, (4.32)
where a1 ∈ C{0}, and ξ1 , ξ2 , ξ3 , ξ4 ∈ C.
Proof. Since wt(Mef )
1 q q
q−4
q−3
q−3 and α1 = q−2
, α2 = q−1
, α3 =
q−1
, we must have e(x1) = a1 , e(x2) = 0, e(x3) = 0. For the same reason, f(x1),
f(x2), f(x3) must be of the following forms:
f(x1) = u1x2
1 +u2x1x2
2 +u3x1x2
3 +u4x1x2x3 +u5x2x3
3 +u6x2
2x2
3 +u7x3
2x3 +u8x4
2 +u9x4
3,
f(x2) = v1x1x2 + v2x1x3 + v3x2x2
3 + v4x2
2x3 + v5x3
2 + v6x3
3,
10. 336 Duplij, Hong, Li
f(x3) = w1x1x2 + w2x1x3 + w3x2x2
3 + w4x2
2x3 + w5x3
2 + w6x3
3,
where these coefficients are in C. Then, we consider (3.18)-(3.19). Taking e(x1),
e(x2), e(x3), f(x1), f(x2), f(x3) into the six equalities, and comparing the
coefficients, we obtain
f(x1) = u1x2
1,
f(x2) = u1x1x2 + v3x2x2
3 + v5x3
2 + v6x3
3,
f(x3) = u1x1x3 + w3x2x2
3 + (1 + q + q2
)v5x2
2x3 − q−1
v3x3
3.
Using ef(u)−fe(u) = k−k−1
q−q−1 (u), for any u ∈ {x1, x2, x3}, we get u1 = −qa−1
1 . So,
the proof is finished.
Lemma 4.3. For Case (∗3), all Uq(sl(2))-module algebra structures on Aq(3)
are as follows
k(x1) = qx1, k(x2) = qx2, k(x3) = q2
x3, (4.33)
e(x1) = −qb−1
3 x1x3 + µ1x2
1x2 − qµ2x3
1 + (1 + q + q2
)µ3x1x2
2, (4.34)
e(x2) = −qb−1
3 x2x3 + µ2x2
1x2 + µ3x3
2 + µ4x3
1, (4.35)
e(x3) = −qb−1
3 x2
3, (4.36)
f(x1) = 0, f(x2) = 0, f(x3) = b3, (4.37)
where b3 ∈ C{0}, and µ1 , µ2 , µ3 µ4 ∈ C.
Proof. The proof is similar to that in Lemma 4.2.
Lemma 4.4. For Case (∗4), to satisfy (3.18)-(3.19), the actions of k, e, f
must be of the following form
k(x1) = qx1, k(x2) = q−1
x2, k(x3) = x3,
e(x1) =
m≥0,p≥0
p=m+3
am,pxm+3
1 xm
2 xp
3 +
m≥0
dmxm+3
1 xm
2 xm+3
3 ,
e(x2) = c21x1 +
m≥0,p≥0
p=m+3
bm,pxm+2
1 xm+1
2 xp
3,
e(x3) =
m≥0,p≥0
p=m+3
cm,pxm+2
1 xm
2 xp+1
3 +
m≥0
emxm+2
1 xm
2 xm+4
3 ,
f(x1) = d12x2 +
m≥0,p≥0
p=m+1
dm,pxm+1
1 xm+2
2 xp
3 +
m≥0
hmxm+1
1 xm+2
2 xm+1
3 ,
f(x2) =
m≥0,p≥0
p=m+1
em,pxm
1 xm+3
2 xp
3,
f(x3) =
m≥0,p≥0
p=m+1
gm,pxm
1 xm+2
2 xp+1
3 +
m≥0
gmxm
1 xm+2
2 xm+2
3 ,
11. Duplij, Hong, Li 337
where c21, d12 ∈ C{0}, the other coefficients are in C and am,p
bm,p
= − (m+p+1)q
qp−1(m+3−p)q
,
bm,p
cm,p
= qp−1(m+3−p)q
(2m+2)q
, dm
em
= −(2m+4)q
(2m+2)q
, dm,p
em,p
= − (m+p+3)q
qp+1(m+1−p)q
, dm,p
gm,p
= −(m+p+3)q
q(2m+2)q
,
hm
gm
= − (2m+4)q
q(2m+2)q
.
In particular, there are the following Uq(sl(2))-module algebra structures on
Aq(3)
k(x1) = qx1, k(x2) = q−1
x2, k(x3) = x3, (4.38)
e(x1) = 0, e(x2) = c21x1, e(x3) = 0, (4.39)
f(x1) = c−1
21 x2, f(x2) = 0, f(x3) = 0, (4.40)
where c21 ∈ C{0}.
Proof. In this case, we get α1 = q, α2 = q−1
, α3 = 1. Therefore, we obtain
wt(Mef )
q3
q q2
q−1
q−3
q−2 . Since wt(e(x1)) = q3
, wt(e(x2)) = q and
wt(e(x3)) = q2
, using (3.18) and by some computations, we can obtain e(x1),
e(x2) and e(x3) in the forms appearing in the lemma. Similarly, we also can
determine the forms of f(x1), f(x2) and f(x3) in the lemma.
Note that (4.38)-(4.40) determine the module-algebra structures of Uq(sl(2))
on Aq(3).
Lemma 4.5. For Case (∗5), to satisfy (3.18)-(3.19), the actions of Uq(sl(2))
on Aq(3) must be of the following form
k(x1) = x1, k(x2) = qx2, k(x3) = q−1
x3,
e(x1) =
m≥0,p≥0
p=m+1
am,pxp+1
1 x2+m
2 xm
3 +
m≥0
amxm+2
1 xm+2
2 xm
3 ,
e(x2) =
m≥0,p≥0
p=m+1
bm,pxp
1x3+m
2 xm
3 ,
e(x3) = c32x2 +
m≥0,p≥0
p=m+1
cm,pxp
1xm+2
2 xm+1
3 +
m≥0
cmxm+1
1 xm+2
2 xm+1
3 ,
f(x1) =
m≥0,p≥0
p=m+3
dm,pxp+1
1 xm
2 xm+2
3 +
m≥0
dmxm+4
1 xm
2 xm+2
3 ,
f(x2) = d23x3 +
m≥0,p≥0
p=m+3
em,pxp
1xm+1
2 xm+2
3 ,
f(x3) =
m≥0,p≥0
p=m+3
gm,pxp
1xm
2 xm+3
3 +
m≥0
gmxm+3
1 xm
2 xm+3
3 ,
where c32 , d23 ∈ C{0}, other coefficients are in C and am,p
bm,p
= (2m+2)q
qp(m−p+1)q
,
am,p
cm,p
= − q(2m+2)q
(m+p+3)q
, am
cm
= −q(2m+2)q
(2m+4)q
, dm,p
em,p
= (2m+2)q
qp−1(m−p+3)q
, dm,p
gm,p
= − (2m+2)q
(m+p+1)q
,
dm
gm
= −(2m+2)q
(2m+4)q
.
12. 338 Duplij, Hong, Li
There are the following Uq(sl(2))-module algebra structures on Aq(3)
k(x1) = x1, k(x2) = qx2, k(x3) = q−1
x3, (4.41)
e(x1) = 0, e(x2) = 0, e(x3) = c32x2, (4.42)
f(x1) = 0, f(x2) = c−1
32 x3, f(x3) = 0, (4.43)
where c32 ∈ C{0}.
Proof. The proof is similar to that in Lemma 4.4.
Lemma 4.6. For Case (∗6) and Case (∗7), to satisfy (3.18)-(3.19), the actions
of k, e and f on Aq(3) are
k(x1) = qx1, k(x2) = q−2
x2, k(x3) = q−1
x3,
e(x1) = σx3
1 +
n≥0
σnx2n+5
1 xn+1
2 +
p≥0
σpxp+4
1 xp+1
3
+
n≥0,p≥0
σn,px2n+p+6
1 xn+1
2 xp+1
3 ,
e(x2) = a2 + ρx2
1x2 +
n≥0
ρnx2n+4
1 xn+2
2 +
p≥0
ρpxp+3
1 x2xp+1
3
+
n≥0,p≥0
ρn,px2n+p+5
1 xn+2
2 xp+1
3 ,
e(x3) = τx2
1x3 +
n≥0
τnx2n+4
1 xn+1
2 x3 +
p≥0
τpxp+3
1 xp+2
3
+
n≥0,p≥0
τn,px2n+p+5
1 xn+1
2 xp+2
3 ,
f(x1) = d13x3 +
p≥0
λpxp+1
1 xp+2
3 +
n≥0
λnx2n+1
1 xn+1
2 +
n≥0
λnx2n+2
1 xn+1
2 x3
+
n≥0,p≥0
λn,px2n+p+3
1 xn+1
2 xp+2
3 ,
f(x2) =
n≥0
νnx2n
1 xn+2
2 +
n≥0
νnx2n+1
1 xn+2
2 x3 +
n≥0,p≥0
νn,px2n+p+2
1 xn+2
2 xp+2
3 ,
f(x3) =
p≥0
ωpxp
1xp+3
3 +
n≥0
ωnx2n
1 xn+1
2 x3 +
n≥0
ωnx2n+1
1 xn+1
2 x2
3
+
n≥0,p≥0
ωn,px2n+p+2
1 xn+1
2 xp+3
3 ,
where a2 ∈ C{0} and the other coefficients are in C, and σ
ρ
= − q2
(4)q
, σn
ρn
=
−q2(n+2)q
(2n+6)q
, σp
ρp
= − (p+2)q
qp−1(4)q
, σn,p
ρn,p
= − (n+p+3)q
qp−1(2n+6)q
, σ
τ
= − q
(3)q
, σn
τn
= −q(n+2)q
(3n+6)q
,
σp
τp
= −q(p+2)q
(p+4)q
, σn,p
τn,p
= −q(n+p+3)q
(3n+p+7)q
, λp
ωp
= − (p+3)q
q(p+1)q
, λn
ωn
= − (n+2)q
q(3n+2)q
, λn
ωn
= − (n+3)q
q(3n+3)q
,
λn,p
ωn,p
= − (n+p+4)q
q(3n+p+4)q
, λn
νn
= − (n+2)q
q(2n+2)q
, λn
νn
= − (n+3)q
q2(2n+2)q
, λn,p
νn,p
= − (n+p+4)q
qp+3(2n+2)q
.
In particular, there are the following Uq(sl(2))-module algebra structures on
13. Duplij, Hong, Li 339
Aq(3):
k(x1) = qx1, k(x2) = q−2
x2, k(x3) = q−1
x3, (4.44)
e(x1) = 0, e(x2) = a2, e(x3) = 0, (4.45)
f(x1) = d13x3 + a−1
2 x1x2 +
n
p=0
dpxp+1
1 xp+2
3 , f(x2) = −qa−1
2 x2
2, (4.46)
f(x3) = −qa−1
2 x2x3 −
n
p=0
q(p + 1)q
(p + 3)q
dpxp
1xp+3
3 , (4.47)
where n ∈ N, d13 , dp ∈ C for all p, a2 ∈ C{0}.
Proof. In these two cases, we have the same values of α1 , α2 and α3 , i.e.,
α1 = q, α2 = q−2
, α3 = q−1
. Therefore, wt(Mef )
q3
1 q
q−1
q−4
q−3 . Using
the equalities (3.18)-(3.19) and by some computations, we can obtain that e(x1),
e(x2), e(x3), f(x1), f(x2), f(x3) are of the forms in this lemma.
Moreover, using (4.44)-(4.47), it is easy to check that ef(u) − fe(u) =
k−k−1
q−q−1 (u), where u ∈ {x1, x2, x3}. Therefore, they determine the module-algebra
structures of Uq(sl(2)) on Aq(3).
Lemma 4.7. For Case (∗8) and Case (∗9), to satisfy (3.18)-(3.19), the actions
of k, e, f are of the form
k(x1) = qx1, k(x2) = q2
x2, k(x3) = q−1
x3,
e(x1) =
p≥0
αpxp+3
1 xp
3 +
m≥0
αmx1xm+1
2 x2m
3 +
m≥0
αmx2
1xm+1
2 x2m+1
3
+
p≥0,m≥0
αm,pxp+3
1 xm+1
2 x2m+p+2
3 ,
e(x2) =
m≥0
βmxm+2
2 x2m
3 +
m≥0
βmx1xm+2
2 x2m+1
3
+
p≥0,m≥0
βm,pxp+2
1 xm+2
2 x2m+p+2
3 ,
e(x3) = c31x1 +
p≥0
γpxp+2
1 xp+1
3 +
m≥0
γmxm+1
2 x2m+1
3 +
m≥0
γmx1xm+1
2 x2m+2
3
+
p≥0,m≥0
γm,pxp+2
1 xm+1
2 x2m+p+3
3 ,
f(x1) = εx1x2
3 +
p≥0
εpxp+2
1 xp+3
3 +
m≥0
εmx1xm+1
2 x2m+4
3
+
m≥0,p≥0
εm,pxp+2
1 xm+1
2 x2m+p+5
3 ,
f(x2) = b2 + θx2x2
3 +
p≥0
θpxp+1
1 x2xp+3
3 +
m≥0
θmxm+2
2 x2m+4
3
+
m≥0,p≥0
θm,pxp+1
1 xm+2
2 x2m+p+5
3 ,
14. 340 Duplij, Hong, Li
f(x3) = ηx3
3 +
p≥0
ηpxp+1
1 xp+4
3 +
m≥0
ηmxm+1
2 x2m+5
3
+
m≥0,p≥0
ηm,pxp+1
1 xm+1
2 x2m+p+6
3 ,
where b2 ∈ C{0} and the other coefficients are in C, and αp
γp
= −q(p+1)q
(p+3)q
, αm
βm
=
(3m+2)q
(2m+2)q
, αm
βm
= (3m+3)q
q(2m+2)q
, αm,p
βm,p
= (3m+p+4)q
qp+2(2m+2)q
, αm
γm
= −q(3m+2)q
(m+2)q
, αm
γm
= −q(3m+3)q
(m+3)q
,
αm,p
γm,p
= −q(3m+p+4)q
(p+m+4)q
, ε
θ
= q(3)q
(4)q
, εp
θp
= (p+4)q
qp(4)q
, εm
θm
= q(3m+6)q
(2m+6)q
, εm,p
θm,p
= (3m+p+7)q
qp(2m+6)q
,
ε
η
= −q−1
(3)q , εp
ηp
= − (p+4)q
q(p+2)q
, εm
ηp
= −(3m+6)q
q(m+2)q
, εm,p
ηm,p
= −(3m+p+7)q
q(p+m+3)q
.
There are the following Uq(sl(2))-module algebra structures on Aq(3)
k(x1) = qx1, k(x2) = q2
x2, k(x3) = q−1
x3, (4.48)
e(x1) = −qb−1
2 x1x2 −
n
p=0
q(p + 1)q
(p + 3)q
αpxp+3
1 xp
3, e(x2) = −qb−1
2 x2
2, (4.49)
e(x3) = c31x1 + e−1
0 x2x3 +
n
p=0
αpxp+2
1 xp+1
3 , (4.50)
f(x1) = 0, f(x2) = b2, f(x3) = 0, (4.51)
where n ∈ N, c31 , αp ∈ C for all p, b2 ∈ C{0}.
Proof. The proof is similar to that in Lemma 4.6.
Lemma 4.8. For Case (∗10), to satisfy (3.18)-(3.19), the actions of k, e, f
on Aq(3) are
k(x1) = qx1, k(x2) = qx2, k(x3) = q−2
x3,
e(x1) =
n≥0,p≥0
2+2p−n≥0
n=p+1
rn,px3+2p−n
1 xn
2 xp
3 +
p≥0
rpx2+p
1 xp+1
2 xp
3,
e(x2) =
n≥0,p≥0
2+2p−n≥0
n=p+1
sn,px2+2p−n
1 xn+1
2 xp
3,
e(x3) = a3 +
n≥0,p≥0
2+2p−n≥0
n=p+1
tn,px2+2p−n
1 xn
2 xp+1
3 +
p≥0
tpxp+1
1 xp+1
2 xp+1
3 ,
f(x1) =
n≥0,p≥0
2p−n≥0
p=n+2
un,px2p−n+1
1 xn
2 xp+1
3 +
n≥0
unxn+5
1 xn
2 xn+3
3 ,
f(x2) =
n≥0,p≥0
2p−n≥0
p=n+2
vn,px2p−n
1 xn+1
2 xp+1
3 ,
15. Duplij, Hong, Li 341
f(x3) =
n≥0,p≥0
2p−n≥0
p=n+2
wn,px2p−n
1 xn
2 xp+2
3 +
n≥0
wnxn+4
1 xn
2 xn+4
3 ,
where a3 ∈ C{0} and the other coefficients are in C, and rn,p
sn,p
= (n+p+1)q
qp+1(p+1−n)q
,
rn,p
tn,p
= −q2(n+p+1)q
(2p+4)q
, rp
tp
= −q2(2p+2)q
(2p+4)q
, un,p
vn,p
= − (n+p+2)q
qp+2(p−2−n)q
, un,p
wn,p
= −(n+p+2)q
q(2p+2)q
,
un
wn
= − (2n+4)q
q(2n+6)q
.
Specifically, there are the following Uq(sl(2))-module algebra structures on
Aq(3)
k(x1) = qx1, k(x2) = qx2, k(x3) = q−2
x3, (4.52)
e(x1) = 0, e(x2) = 0, e(x3) = a3, (4.53)
f(x1) = a−1
3 x1x3, f(x2) = a−1
3 x2x3, f(x3) = −qa−1
3 x2
3, (4.54)
where a3 ∈ C{0}.
Proof. In this case, we have α1 = q, α2 = q, α3 = q−2
. Therefore, wt(Mef )
q3
q3
1
q−1
q−1
q−4 . Then, the proof is similar to those in the above lemmas.
Lemma 4.9. For Case (∗11), to satisfy (3.18)-(3.19), the actions of k, e and
f on Aq(3) are
k(x1) = q2
x1, k(x2) = q−1
x2, k(x3) = q−1
x3,
e(x1) =
m≥0,p≥0
2m−p≥0
m=p+2
rm,pxm+2
1 xp
2x2m−p
3 +
p≥0
rpxp+4
1 xp
2xp+4
3 ,
e(x2) =
m≥0,p≥0
2m−p≥0
m=p+2
sm,pxm+1
1 xp+1
2 x2m−p
3 ,
e(x3) =
m≥0,p≥0
2m−p≥0
m=p+2
tn,pxm+1
1 xp
2x2m−p+1
3 +
p≥0
tpxp+3
1 xp
2xp+5
3 ,
f(x1) = b1 +
m≥0,p≥0
2m+2−p≥0
p=m+1
um,pxm+1
1 xp
2x2m+2−p
3 +
m≥0
umxm+1
1 xm+1
2 xm+1
3 ,
f(x2) =
m≥0,p≥0
2m+2−p≥0
p=m+1
vm,pxm
1 xp+1
2 x2m−p+2
3 ,
f(x3) =
n≥0,p≥0
2m+2−p≥0
p=m+1
wm,pxm
1 xp
2x2m−p+3
3 +
m≥0
wmxm
1 xm+1
2 xm+2
3 ,
where b1 ∈ C{0} and the other coefficients are in C, and rm,p
sm,p
= (2m+2)q
qm+1(m−2−p)q
,
16. 342 Duplij, Hong, Li
rm,p
tm,p
= − q(2m+2)q
(m+p+2)q
, rp
tp
= −q(2p+6)q
(2p+4)q
, um,p
vm,p
= (2m+4)q
qm+3(m+1−p)q
, um,p
wm,p
= − (2m+4)q
q2(m+p+1)q
,
um
wm
= − (2m+4)q
q2(2m+2)q
.
There are the following Uq(sl(2))-module algebra structures on Aq(3)
k(x1) = q2
x1, k(x2) = q−1
x2, k(x3) = q−1
x3, (4.55)
e(x1) = −qb−1
1 x2
1, e(x2) = b−1
1 x1x2, e(x3) = b−1
1 x1x3, (4.56)
f(x1) = b1, f(x2) = 0, f(x3) = 0, (4.57)
where b1 ∈ C{0}.
Proof. The proof is similar to that in Lemma 4.8.
Next, we begin to classify all module-algebra structures of Uq(sl(3)) =
H(ei, fi, k±1
i )i=1,2 on Aq(3) when ki ∈ Aut L(Aq(3)) for i = 1, 2.
For Uq(sl(3)), there are two sub-Hopf algebras which are isomorphic to
Uq(sl(2)). One is generated by k1 , e1 and f1 . Denote this algebra by A. The
other one, denoted by B, is generated by k2 , e2 and f2 . By the definition of
module algebra of one Hopf algebra, the module-algebra structures on Aq(2) of
these two sub-Hopf algebras are of the kinds discussed above.
Denote 9 cases of the actions of k1 , e1 , f1 (resp. k2 , e2 , f2 ) in Lemma
4.1-Lemma 4.9 by (A1), · · · , (A9) (resp. (B1), · · · , (B9)). To determine
all module-algebra structures of Uq(sl(3)) = H(ei, fi, k±1
i )i=1,2 on Aq(3) when
ki ∈ Aut L(Aq(3)) for i = 1, 2, we have to find all the actions of k1 , e1 , f1 and
k2 , e2 , f2 which are compatible, i.e., the following equalities hold
k1e2(u) = q−1
e2k1(u), k1f2(u) = qf2k1(u), (4.58)
k2e1(u) = q−1
e1k2(u), k2f1(u) = qf1k2(u), (4.59)
e1f2(u) = f2e1(u), e2f1(u) = f1e2(u), (4.60)
e2
1e2(u) − (q + q−1
)e1e2e1(u) + e2e2
1(u) = 0, (4.61)
e2
2e1(u) − (q + q−1
)e2e1e2(u) + e1e2
2(u) = 0, (4.62)
f2
1 f2(u) − (q + q−1
)f1f2f1(u) + f2f2
1 (u) = 0, (4.63)
f2
2 f1(u) − (q + q−1
)f2f1f2(u) + f1f2
2 (u) = 0, (4.64)
and eifi(u) − fiei(u) =
ki−k−1
i
q−q−1 (u) holds for u ∈ {x1, x2, x3} and i ∈ {1, 2}.
Because the actions of k1 , e1 , f1 and k2 , e2 , f2 in Uq(sl(3)) are symmetric,
we only need to check 45 cases, i.e., whether (Ai) is compatible with (Bj) for any
1 ≤ i ≤ j ≤ 9. We use (Ai)|(Bj) to denote that the actions of k1 , e1 , f1 are
those in (Ai) and the actions of k2 , e2 , f2 are those in (Bj). Moreover, in Case
(Aj)|(Bj) (j ≥ 2), since the actions of ei , fi are not zero simultaneously for
i ∈ {1, 2}, (4.58) and (4.59) can not be satisfied simultaneously. Therefore, the
Cases (Aj)|(Bj) (j ≥ 2) should be excluded.
First, let us consider Case (A2)|(B5). Since k2e1(x1) = k2(a1) = a1 ,
q−1
e1k2(x1) = q−1
a1 and a1 = 0, k2e1(x1) = q−1
e1k2(x1) does not hold. Therefore,
(A2)|(B5) should be excluded. For the same reason, we exclude (A2)|(B6),
(A2)|(B8), (A2)|(B9), (A3)|(B4), (A3)|(B7), (A3)|(B8), (A3)|(B9), (A4)|(B6),
17. Duplij, Hong, Li 343
(A4)|(B7), (A4)|(B8), (A4)|(B9), (A5)|(B7), (A5)|(B8), (A5)|(B9), (A6)|(B7),
(A6)|(B8), (A6)|(B9), (A7)|(B8), (A7)|(B9), (A8)|(B9).
Second, we consider (A1)|(B2). Since k1f2(x1) = −qa−1
1 x2
1 and qf2k1(x1) =
q2
a−1
1 x2
1 , we have k1f2(x1) = qf2k1(x1). Thus, (A1)|(B2) should be excluded.
Similarly, (A1)|(Bi) should be excluded for i ≥ 3.
Therefore, we only need to consider the following cases: (A1)|(B1), (A2)|
(B3), (A2)|(B4), (A2)|(B7), (A3)|(B5), (A3)|(B6), (A4)|(B5), (A4)|(B7), (A5)
|(B6).
Lemma 4.10. For Case (A1)|(B1), all module-algebra structures of Uq(sl(3))
on Aq(3) are as follows
ki(xj) = ±xj, ei(xj) = 0, fi(xj) = 0,
for i ∈ {1, 2}, j ∈ {1, 2, 3}, which are pairwise non-isomorphic.
Proof. It can be seen that (4.58)-(4.64) are satisfied for any u ∈ {x1, x2, x3}
in this case. Therefore, they are module-algebra structures of Uq(sl(3)) on Aq(3).
Since all the automorphisms of Aq(3) commute with the actions of k1 and k2 , all
these module-algebra structures are pairwise non-isomorphic.
Lemma 4.11. For Case (A2)|(B3), all Uq(sl(3))-module algebra structures on
Aq(3) are as follows:
k1(x1) = q−2
x1, k1(x2) = q−1
x2, k1(x3) = q−1
x3,
k2(x1) = qx1, k2(x2) = qx2, k2(x3) = q2
x3,
e1(x1) = a1, e1(x2) = 0, e1(x3) = 0,
e2(x1) = −qb−1
3 x1x3, e2(x2) = −qb−1
3 x2x3, e2(x3) = −qb−1
3 x2
3,
f1(x1) = −qa−1
1 x2
1, f1(x2) = −qa−1
1 x1x2, f1(x3) = −qa−1
1 x1x3,
f2(x1) = 0, f2(x2) = 0, f2(x3) = b3,
where a1 , b3 ∈ C{0}.
All these structures are isomorphic to that with a1 = b3 = 1.
Proof. By Lemma 4.2 and Lemma 4.3, to determine the module-algebra struc-
tures of Uq(sl(3)) on Aq(3), we have to make (4.58)-(4.64) hold for any u ∈
{x1, x2, x3} using the actions of k1 , e1 , f1 in Lemma 4.2 and the actions of k2 ,
e2 , f2 in Lemma 4.3.
Since k1e2(x1) = q−1
e2k1(x1) = q−3
e2(x1), we have e2(x1) = −qb−1
3 x1x3 ,
i.e., µ1 = µ2 = µ3 = 0. Using k1e2(x2) = q−1
e2k1(x2) = q−2
e2(x2), we ob-
tain e2(x2) = −qb−1
3 x2x3 . Similarly, by k2f1(x2) = qf1k2(x2) = q2
f1(x2) and
k2f1(x3) = qf1k2(x3) = q3
f1(x3), we get f1(x2) = −qa−1
1 x1x2 and f1(x3) =
−qa−1
1 x1x3 . Then, it is easy to check that (4.58)-(4.59) hold for any u ∈ {x1, x2, x3}.
Then, we check that (4.60) holds. Obviously, e1f2(u) = f2e1(u) for any
18. 344 Duplij, Hong, Li
u ∈ {x1, x2, x3}. Now, we check e2f1(x1) − f1e2(x1) = 0. In fact,
e2f1(x1) − f1e2(x1)
= e2(−qa−1
1 x2
1) − f1(−qb−1
3 x1x3)
= −qa−1
1 (x1e2(x1) + e2(x1)k2(x1)) + qb−1
3 (k−1
1 (x1)f1(x3) + f1(x1)x3)
= (q2
+ q4
)a−1
1 b−1
3 x2
1x3 − (q4
+ q2
)a−1
1 b−1
3 x2
1x3
= 0.
Similarly, other equalities in (4.60) can be checked.
Next, we check that (4.61)-(4.64) hold for any u ∈ {x1, x2, x3}. We only
check
e2
2e1(x1) − (q + q−1
)e2e1e2(x1) + e1e2
2(x1) = 0.
In fact,
e2
2e1(x1) − (q + q−1
)e2e1e2(x1) + e1e2
2(x1)
= 0 − (q + q−1
)e2e1(−qb−1
3 x1x3) + e1e2(−qb−1
3 x1x3)
= (q + q−1
)b−1
3 e2(a1x3) − qb−1
3 e1(−qb−1
3 x1x2
3 − q3
b−1
3 x1x2
3)
= −q(q + q−1
)a1b−2
3 x2
3 + a1b−2
3 (1 + q2
)x2
3
= 0.
The other equalities can be checked similarly.
Finally, we claim that all the actions with nonzero a1 and b3 are isomorphic
to the specific action with a1 = 1, b3 = 1. The desired isomorphism is given by
ψa1,b3 : x1 → a1x1, x2 → x2, x3 → b3x3 .
Lemma 4.12. For Case (A2)|(B4), all Uq(sl(3))-module algebra structures on
Aq(3) are as follows
k1(x1) = q−2
x1, k1(x2) = q−1
x2, k1(x3) = q−1
x3,
k2(x1) = qx1, k2(x2) = q−1
x2, k2(x3) = x3,
e1(x1) = a1, e1(x2) = 0, e1(x3) = 0,
e2(x1) = 0, e2(x2) = c21x1, e2(x3) = 0,
f1(x1) = −qa−1
1 x2
1, f1(x2) = −qa−1
1 x1x2, f1(x3) = −qa−1
1 x1x3,
f2(x1) = c−1
21 x2, f2(x2) = 0, f2(x3) = 0,
where a1 , c21 ∈ C{0}.
All these module-algebra structures are isomorphic to that with a1 = c21 = 1.
Proof. By the above actions of k1 , e1 , f1 and k2 , e2 , f2 , it is easy to check
that (4.58)-(4.64) hold for any u ∈ {x1, x2, x3}. Therefore, by Lemma 4.2 and
Lemma 4.4, they determine the module-algebra structures of Uq(sl(3)) on Aq(3).
Next, we prove that there are no other actions except these in this lemma.
Using k1e2(x1) = q−1
e2k1(x1) = q−3
e2(x1), we can obtain e2(x1) = 0. By
Lemma 4.4, we also have e2(x2) = c21x1 and e2(x3) = 0. Similarly, by k1f2(x1) =
qf2k1(x1) = q−1
f2(x1), we get f2(x1) = d12x2 . Therefore, f2(x2) = f2(x3) = 0.
19. Duplij, Hong, Li 345
Then, using e2f2(xi) − f2e2(xi) =
k2−k−1
2
q−q−1 (xi) for any i ∈ {1, 2, 3}, we obtain d12 =
c−1
21 . Since k2f1(x2) = qf1k2(x2) = f1(x2) and k2f1(x3) = qf1k2(x3) = qf1(x3), by
Lemma 4.2, we have f1(x2) = −qa−1
1 x1x2 + ξ3x3
3 , f1(x3) = −qa−1
1 x1x3 .
Due to the conditions of the module algebra, it is easy to see that we have
to let f2
1 f2(x3) − (q + q−1
)f1f2f1(x3) + f2f2
1 (x3) = 0 hold. On the other hand, we
have
f2
1 f2(x3) − (q + q−1
)f1f2f1(x3) + f2f2
1 (x3)
= −(q + q−1
)f1f2(−qa−1
1 x1x3) + f2f1(−qa−1
1 x1x3)
= q(q + q−1
)a−1
1 c−1
21 f1(x2x3) − qa−1
1 f2(f1(x1)x3 + q2
x1f1(x3))
= q(q + q−1
)a−1
1 c−1
21 (f1(x2)x3 + qx2f1(x3)) + qa−2
1 (q + q3
)f2(x2
1x3)
= (q2
+ 1)a−1
1 c−1
21 (−(q + q3
)a−1
1 x1x2x3 + ξ3x4
3)
+(q2
+ 1)(q + q3
)c−1
21 a−2
1 x1x2x3
= (q2
+ 1)a−1
1 c−1
21 ξ3x4
3.
Hence, we get ξ3 = 0. Therefore, f1(x2) = −qa−1
1 x1x2 . Thus, there are no other
actions except those in this lemma.
Finally, we claim that all the actions with nonzero a1 and c21 are isomorphic
to the specific action with a1 = 1, c21 = 1. The desired isomorphism is given by
ψa1,c21 : x1 → a1x1, x2 → a1c21x2, x3 → x3 .
Lemma 4.13. For Case (A2)|(B7), all module-algebra structures of Uq(sl(3))
on Aq(3) are as follows
k1(x1) = q−2
x1, k1(x2) = q−1
x2, k1(x3) = q−1
x3,
k2(x1) = qx1, k2(x2) = q2
x2, k2(x3) = q−1
x3,
e1(x1) = a1, e1(x2) = 0, e1(x3) = 0,
e2(x1) = −qb−1
2 x1x2, e2(x2) = −qb−1
2 x2
2, e2(x3) = c31x1 + b−1
2 x2x3,
f1(x1) = −qa−1
1 x2
1, f1(x2) = −qa−1
1 x1x2, f1(x3) = −qa−1
1 x1x3 + ξ4x2x2
3,
f2(x1) = 0, f2(x2) = b2, f2(x3) = 0,
where a1 , b2 , c31 , ξ4 ∈ C{0} and c31ξ4 = −qb−1
2 a−1
1 .
All module-algebra structures above are isomorphic to that with a1 = b2 =
c31 = 1 and ξ4 = −q.
Proof. By the above actions of k1 , e1 , f1 and k2 , e2 , f2 , it is easy to check
that (4.58)-(4.64) hold for any u ∈ {x1, x2, x3}. Therefore, by Lemma 4.2 and
Lemma 4.7, they determine the module-algebra structures of Uq(sl(3)) on Aq(3).
Next, we prove that there are no other actions except those in this lemma.
By (4.58), we can immediately obtain that e2(x1) = α0x1x2 , e2(x2) = β0x2
2 ,
e2(x3) = c31x1 + γ0x2x3 , f2(x1) = 0, f2(x2) = b2 and f2(x3) = 0. By Lemma
4.7, α0 = β0 = −qγ0 . According to e2f2(x1) − f2e2(x1) =
k2−k−1
2
q−q−1 (x1), we obtain
γ0 = b−1
2 . Similarly, by (4.59), we have f1(x1) = −qa−1
1 x2
1 , f1(x2) = −qa−1
1 x1x2
and f1(x3) = −qa−1
1 x1x3 + ξ4x2x2
3 .
20. 346 Duplij, Hong, Li
Next, let us consider the condition e2f1(x3) − f1e2(x3) = 0. Since
e2f1(x3) − f1e2(x3)
= e2(−qa−1
1 x1x3 + ξ4x2x2
3) − f1(c31x1 + b−1
2 x2x3)
= −qa−1
1 (x1e2(x3) + e2(x1)k2(x3)) + ξ4(x2x3e2(x3) + x2e2(x3)k2(x3)
+e2(x2)k2(x3)k2(x3)) + qc31a−1
1 x2
1 − b−1
2 (k−1
1 (x2)f1(x3) + f1(x2)x3)
= ξ4c31(q2
+ 1)x1x2x3 + a−1
1 b−1
2 (q3
+ q)x1x2x3
= 0,
we obtain ξ4c31 = −qa−1
1 b−1
2 .
Therefore, there are no other actions except those in this lemma.
Finally, we show that all the actions with nonzero a1 , c31 , b2 and ξ4 are
isomorphic to the specific action with a1 = b2 = c31 = 1 and ξ4 = −q. The desired
isomorphism is given by ψa1,c31,b2 : x1 → a1x1, x2 → b2x2, x3 → a1c31x3 .
Lemma 4.14. For Case (A3)|(B5), all module-algebra structures of Uq(sl(3))
on Aq(3) are as follows:
k1(x1) = qx1, k1(x2) = qx2, k1(x3) = q2
x3,
k2(x1) = x1, k2(x2) = qx2, k2(x3) = q−1
x3,
e1(x1) = −qb−1
3 x1x3, e1(x2) = −qb−1
3 x2x3, e1(x3) = −qb−1
3 x2
3,
e2(x1) = 0, e2(x2) = 0, e2(x3) = c32x2,
f1(x1) = 0, f1(x2) = 0, f1(x3) = b3,
f2(x1) = 0, f2(x2) = c−1
32 x3, f2(x3) = 0,
where b3 , c32 ∈ C{0}.
All module-algebra structures above are isomorphic to that with b3 = c32 =
1.
Proof. The proof is similar to that in Lemma 4.12.
Lemma 4.15. For Case (A3)|(B6), all module-algebra structures of Uq(sl(3))
on Aq(3) are as follows:
k1(x1) = qx1, k1(x2) = qx2, k1(x3) = q2
x3,
k2(x1) = qx1, k2(x2) = q−2
x2, k2(x3) = q−1
x3,
e1(x1) = −qb−1
3 x1x3 + µ1x2
1x2, e1(x2) = −qb−1
3 x2x3, e1(x3) = −qb−1
3 x2
3,
e2(x1) = 0, e2(x2) = a2, e2(x3) = 0,
f1(x1) = 0, f1(x2) = 0, f1(x3) = b3,
f2(x1) = d13x3 + a−1
2 x1x2, f2(x2) = −qa−1
2 x2
2, f2(x3) = −qa−1
2 x2x3,
where d13 , a2 , µ1 , b3 ∈ C{0} and µ1d13 = −qa−1
2 b−1
3 .
All module-algebra structures above are isomorphic to that with d13 = a2 =
b3 = 1 and µ1 = −q.
21. Duplij, Hong, Li 347
Proof. The proof is similar to that in Lemma 4.13.
Lemma 4.16. For Case (A4)|(B5), all module-algebra structures of Uq(sl(3))
on Aq(3) are as follows:
k1(x1) = qx1, k1(x2) = q−1
x2, k1(x3) = x3,
k2(x1) = x1, k2(x2) = qx2, k2(x3) = q−1
x3,
e1(x1) = 0, e1(x2) = c21x1, e1(x3) = 0,
e2(x1) = 0, e2(x2) = 0, e2(x3) = c32x2,
f1(x1) = c−1
21 x2, f1(x2) = 0, f1(x3) = 0,
f2(x1) = 0, f2(x2) = c−1
32 x3, f2(x3) = 0,
where c21 , c32 ∈ C{0}.
All the above module-algebra structures are isomorphic to that with c21 =
c32 = 1.
Proof. By the actions of k1 , e1 , f1 and k2 , e2 , f2 , it is easy to check that
(4.58)-(4.64) hold for any u ∈ {x1, x2, x3}. Therefore, by Lemma 4.4 and Lemma
4.5, they determine the module-algebra structures of Uq(sl(3)) on Aq(3).
Next, we prove that there are no other actions except these in this lemma.
By Lemma 4.5 and using that (4.58) holds for any u ∈ {x1, x2, x3}, we
can obtain that e2(x1) = n≥0 anxn+2
1 xn+2
2 xn
3 , e2(x2) = 0, e2(x3) = c32x2 +
n≥0 cnxn+1
1 xn+2
2 · xn+1
3 , f2(x1) = m≥0 dm,m+1xm+2
1 xm
2 xm+2
3 , f2(x2) = d23x3 +
m≥0 em,m+1xm+1
1 xm+1
2 xm+2
3 , f2(x3) = m≥0 gm,m+1xm+1
1 xm
2 xm+3
3 .
By Lemma 4.5, we know that an
cn
= −q(2n+2)q
(2n+4)q
, dm,m+1
em,m+1
= (2m+2)q
qm(2)q
, dm,m+1
gm,m+1
=
q2m+2−1
1−q2m+2 = −1. Set vn = an
cn
and κm = dm,m+1
em,m+1
.
Next, we consider e2f2(x2) − f2e2(x2) =
k2−k−1
2
q−q−1 (x2) = x2 . By some compu-
tations, we obtain
e2f2(x2) − f2e2(x2)
= c32d23x2 +
n≥0
(q2n+4
− 1)d23vnxn+1
1 xn+2
2 xn+1
3
−
m≥0
(q−1
− q2m+3
)c32κmxm+1
1 xm+2
2 xm+1
3 +
m≥0,n≥0
q3mn+3m+3n+2
(1 − q2
)
·(1 − q2m+2n+6
)vnκmxm+n+2
1 xm+n+3
2 xm+n+2
3 .
If there exist vn and κm not equal to zero, we can choose the terms with coefficients
vne and κmf
in e2(x1), e2(x2), e2(x3), f2(x1), f2(x2), f2(x3) such that their
degrees are highest. Then, the unique monomial of the highest degree in
(e2f2 − f2e2) (x2) is
q3mf ne+3mf +3ne+2
(1 − q2
)(1 − q2mf +2ne+6
)vne κmf
x
mf +ne+2
1 x
mf +ne+3
2 x
mf +ne+2
3 .
Since the degree of this term is larger than 1, this case is impossible. Similarly, all
cases except that all vn , κm are equal to zero should be excluded. Therefore, we
22. 348 Duplij, Hong, Li
obtain that e2(x1) = 0, e2(x2) = 0, e2(x3) = c32x2 , f2(x1) = 0, f2(x2) = c−1
32 x3
and f2(x3) = 0.
Similarly, using (4.59), Lemma 4.4 and e1f1(u) − f1e1(u) =
k1−k−1
1
q−q−1 (u) for
any u ∈ {x1, x2, x3}, we can obtain e1(x1) = 0, e1(x2) = c21x1 , e1(x3) = 0,
f1(x1) = c−1
21 x2 , f1(x2) = 0, f1(x3) = 0.
Therefore, there are no other actions except the ones in this lemma.
Finally, we claim that all the actions with nonzero c21 , c32 are isomorphic
to the specific action with c21 = c32 = 1. The desired isomorphism is given by
ψc21,c32 : x1 → x1, x2 → c21x2, x3 → c21c32x3 .
Lemma 4.17. For Case (A5)|(B6), all module-algebra structures of Uq(sl(3))
on Aq(3) are
k1(x1) = x1, k1(x2) = qx2, k1(x3) = q−1
x3,
k2(x1) = qx1, k2(x2) = q−2
x2, k2(x3) = q−1
x3,
e1(x1) = 0, e1(x2) = 0, e1(x3) = c32x2,
e2(x1) = 0, e2(x2) = a2, e2(x3) = 0,
f1(x1) = 0, f1(x2) = c−1
32 x3, f1(x3) = 0,
f2(x1) = a−1
2 x1x2, f2(x2) = −qa−1
2 x2
2, f2(x3) = −qa−1
2 x2x3,
where c32 , a2 ∈ C{0}.
All module-algebra structures are isomorphic to that with a2 = c32 = 1.
Proof. It is easy to check that the above actions of k1 , e1 , f1 and k2 , e2 , f2
determine module-algebra structures of Uq(sl(3)) on Aq(3).
Then we will prove that there are no other actions except for those in this
lemma.
By (4.58) for any u ∈ {x1, x2, x3} and Lemma 4.6, we have
e2(x1) = (q − q3
)ux4
1x3 +
n≥0
(q − q2n+5
)vnx3n+7
1 xn+1
2 xn+2
3 ,
e2(x2) = a2 + (q4
− 1)ux3
1x2x3 +
n≥0
(q3n+7
− qn+1
)vnx3n+6
1 xn+2
2 xn+2
3 ,
e2(x3) = (q4
− 1)ux3
1x2
3 +
n≥0
(q4n+8
− 1)vnx3n+6
1 xn+1
2 xn+3
3 ,
f2(x1) = gx1x2 + (q3
− q−1
)εx4
1x2
2x3 +
p≥0
(q2p+5
− q−1
)µpx3p+7
1 xp+3
2 xp+2
3 ,
f2(x2) = −qgx2
2 + (q − q5
)εx3
1x3
2x3 +
p≥0
(qp+2
− q3p+8
)µpx3p+6
1 xp+4
2 xp+2
3 ,
f2(x3) = −qgx2x3 + (1 − q6
)εx3
1x2
2x2
3 +
p≥0
(1 − q4p+10
)µpx3p+6
1 xp+3
2 xp+3
3 .
Then we will consider the condition e2f2(u) − f2e2(u) =
k2−k−1
2
q−q−1 (u) for any
u ∈ {x1, x2, x3}.
23. Duplij, Hong, Li 349
Let us assume that there exist some u or vn which are not equal to zero.
Then, we can choose the monomials in e2(x1), e2(x2), e2(x3) with the highest
degree. Obviously, these monomials are unique. It is also easy to see that f(x1),
f(x2), f(x3) can not be equal to zero simultaneously. Therefore, there are some
nonzero g, ε or µp . Similarly, those monomials in f2(x1), f2(x2), f2(x3) with
the highest degree are chosen. Then, by some computations, we can obtain a
monomial with the highest degree, whose degree is larger than 1. Then, we get a
contradiction with e2f2(x1) − f2e2(x1) = x1 . For example, if the coefficient of the
monomials in e2(x1), e2(x2) and e2(x3) is vne and the coefficient of the monomials
in f2(x1), f2(x2), f2(x3) with the highest degree is µpf
, then the monomial with
the highest degree in e2f2(x1) − f2e2(x1) is
q7nepf +15ne+11pf +22
(1 − q2ne+2pf +10
)2
vne µpf
x
3ne+3pf +13
1 x
ne+pf +4
2 x
ne+pf +4
3 .
Therefore, all u, vn are equal to zero. Then, e2(x1) = 0, e2(x2) = a2 and
e2(x3) = 0. Thus, we can obtain
e2f2(x1) − f2e2(x1)
= ga2x1+(1−q−4
)(1+q2
)εa2x4
1x2x3+ p≥0
1−q2p+6
1−q2 (q−1−p
−q−3p−7
)a2µpx3p+7
1 xp+2
2 xp+2
3 .
Thus, we also obtain f2(x1) = a−1
2 x1x2 , f2(x2) = −qa−1
2 x2
2 and f2(x3) = −qa−1
2 x2x3 .
On the other hand, by a similar discussion, from (4.59), Lemma 4.5 and
e1f1(u) − f1e1(u) =
k1−k−1
1
q−q−1 (u) for any u ∈ {x1, x2, x3}, we can obtain e1(x1) = 0,
e1(x2) = 0, e1(x3) = c32x2 , f1(x1) = 0, f1(x2) = c−1
32 x3 , f1(x3) = 0.
Therefore, there are no other actions except those in this lemma.
Finally, we claim that all module algebra structures with nonzero a2 , c32
are isomorphic to that with a2 = c32 = 1. The desired isomorphism is given by
ψa2,c32 : x1 → x1, x2 → a2x2, x3 → a2c32x3.
Lemma 4.18. For Case (A4)|(B7), all module-algebra structures of Uq(sl(3))
on Aq(3) are as follows
k1(x1) = qx1, k1(x2) = q−1
x2, k1(x3) = x3,
k2(x1) = qx1, k2(x2) = q2
x2, k2(x3) = q−1
x3,
e1(x1) = 0, e1(x2) = c21x1, e1(x3) = 0,
e2(x1) = −qb−1
2 x1x2, e2(x2) = −qb−1
2 x2
2, e2(x3) = b−1
2 x2x3,
f1(x1) = c−1
21 x2, f1(x2) = 0, f1(x3) = 0,
f2(x1) = 0, f2(x2) = b2, f2(x3) = 0,
where b2 , c21 ∈ C{0}.
All module-algebra structures are isomorphic to that with b2 = c21 = 1.
Proof. The proof is similar to that in Lemma 4.17.
5. Classification of Uq(sl(m + 1))-module algebra structures on
Aq(3) and Aq(2)
In this section, we will present the classification of Uq(sl(m + 1))-module algebra
structures on Aq(3) and similarly, on Aq(2) for m ≥ 2.
24. 350 Duplij, Hong, Li
The associated classical limit actions of sl3 (which here is the Lie algebra
generated by h1 , h2 , e1 , e2 , f1 , f2 with the relations [e1, f1] = h1 , [e2, f2] = h2 ,
[e1, f2] = [e2, f1] = 0, [h1, e1] = 2e1 , [h1, e2] = −e2 , [h2, e2] = 2e2 , [h2, e1] =
−e1 , [h1, f1] = −2f1 , [h1, f2] = f2 , [h2, f2] = −2f2 , [h2, f1] = f1 , [h1, h2] =
0) on C[x1, x2, x3] by differentiations are derived from the quantum actions via
substituting k1 = qh1
, k2 = qh2
with a subsequent formal passage to the limit as
q → 1.
Since the actions of k1 , e1 , f1 and k2 , e2 , f2 in Uq(sl(3)) are symmetric,
by Lemma 4.10-Lemma 4.18 and the discussion above, we obtain the following
theorem.
Theorem 5.1. Uq(sl(3)) = H(ei, fi, k±1
i )i=1,2 -module algebra structures up to
isomorphisms on Aq(3) when ki ∈ Aut L(Aq(3)) for i = 1, 2 and their classical
limits, i.e., Lie algebra sl3 -actions by differentiations on C[x1, x2, x3] are as fol-
lows:
Uq(sl(3))-module Classical limit
algebra structures sl3-actions on C[x1, x2, x3]
ki(xs) = ±xs, kj(xs) = ±xs, hi(xs) = 0, hj(xs) = 0,
ei(xs) = 0, ej(xs) = 0, ei(xs) = 0, ej(xs) = 0,
fi(xs) = 0, fj(xs) = 0, fi(xs) = 0, fj(xs) = 0,
s ∈ {1, 2, 3} s ∈ {1, 2, 3}
ki(x1) = q−2
x1, ki(x2) = q−1
x2, hi(x1) = −2x1, hi(x2) = −x2,
ki(x3) = q−1
x3, kj(x1) = qx1, hi(x3) = −x3, hj(x1) = x1,
kj(x2) = qx2, kj(x3) = q2
x3, hj(x2) = x2, hj(x3) = 2x3,
ei(x1) = 1, ei(x2) = 0, ei(x3) = 0, ei(x1) = 1, ei(x2) = 0, ei(x3) = 0,
ej(x1) = −qx1x3, ej(x2) = −qx2x3, ej(x1) = −x1x3, ej(x2) = −x2x3,
ej(x3) = −qx2
3, fi(x1) = −qx2
1, ej(x3) = −x2
3, fi(x1) = −x2
1,
fi(x2) = −qx1x2, fi(x3) = −qx1x3, fi(x2) = −x1x2, fi(x3) = −x1x3,
fj(x1) = 0, fj(x2) = 0, fj(x3) = 1 fj(x1) = 0, fj(x2) = 0, fj(x3) = 1
ki(x1) = q−2
x1, ki(x2) = q−1
x2, hi(x1) = −2x1, hi(x2) = −x2,
ki(x3) = q−1
x3, kj(x1) = qx1, hi(x3) = −x3, hj(x1) = x1,
kj(x2) = q−1
x2, kj(x3) = x3, hj(x2) = −x2, hj(x3) = 0,
ei(x1) = 1, ei(x2) = 0, ei(x3) = 0, ei(x1) = 1, ei(x2) = 0, ei(x3) = 0,
ej(x1) = 0, ej(x2) = x1, ej(x3) = 0, ej(x1) = 0, ej(x2) = x1, ej(x3) = 0,
fi(x1) = −qx2
1, fi(x2) = −qx1x2, fi(x1) = −x2
1, fi(x2) = −x1x2,
fi(x3) = −qx1x3, fi(x3) = −x1x3,
fj(x1) = x2, fj(x2) = 0, fj(x3) = 0 fj(x1) = x2, fj(x2) = 0, fj(x3) = 0
26. 352 Duplij, Hong, Li
for any i = 1, j = 2 or i = 2, j = 1. Moreover, there are no isomorphisms be-
tween these nine kinds of module-algebra structures.
Remark 5.2. Case (5) when i = 1, j = 2 in Theorem 5.1 is the case discussed
in [15] when n = 3.
Let us denote the actions of Uq(sl(2)) on Aq(3) in (A1), those in (A2) and
(B3) in Lemma 4.11, those in (B4) in Lemma 4.12, those in (B5) in Lemma 4.14,
those in (B6) in Lemma 4.17 and those in (B7) in Lemma 4.18 by 1, 2, 3, 4,
5, 6, 7 respectively. In addition, denote the actions of Uq(sl(2)) on Aq(3) in
(A2) and (B7) in Lemma 4.13, those in (A3) and (B6) in Lemma 4.15 by 2 , 7 ,
3 , 6 respectively. If s and t are compatible, in other words, they determine
a Uq(sl(3))-module algebra structure on Aq(3), we use an edge connecting s and
t, since k1 , e1 , f1 and k2 , e2 , f2 are symmetric in Uq(sl(3)). Then, we can use
the following diagrams to denote all actions of Uq(sl(3)) = H(ei, fi, ki, k−1
i )i=1,2 on
Aq(3) when ki ∈ Aut L(Aq(3)) for i = 1, 2:
1 1 , 7 2 , 3 6 , (5.65)
2 3
7 4 5 6
. (5.66)
Here, every two adjacent vertices corresponds to two classes of the module-algebra
structures of Uq(sl(3)) on Aq(3). For example, 2 3 corresponds to the
following two kinds of module-algebra structures of Uq(sl(3)) on Aq(3): one has
actions of k1 , e1 , f1 that are of type 2 and actions of k2 , e2 , f2 that are of type
3; the other has actions of k1 , e1 , f1 that are of type 3 and actions of k2 , e2 ,
f2 that are of type 2.
Next, we will begin to study the module-algebra structures of Uq(sl(m +
1)) = H(ei, fi, k±1
i )1≤i≤m on Aq(3), when ki ∈ Aut L(Aq(3)) for i = 1, · · · , m and
m ≥ 3. The corresponding Dynkin diagram of sl(m + 1) with m vertices is as
follows:
◦ ◦ · · · ◦ ◦ .
In Uq(sl(m + 1)), every vertex corresponds to one Hopf subalgebra isomorphic to
Uq(sl(2)) and two adjacent vertices correspond to one Hopf subalgebra isomorphic
to Uq(sl(3)). Therefore, for studying the module-algebra structures of Uq(sl(m +
1)) on Aq(3), we have to endow every vertex in the Dynkin diagram of sl(m + 1)
an action of Uq(sl(2)) on Aq(3). Moreover, there are some rules which we should
obey:
1. Since every pair of adjacent vertices in the Dynkin diagram corresponds to
one Hopf subalgebra isomorphic to Uq(sl(3)), by Theorem 5.1, the action of
Uq(sl(2)) on Aq(3) on every vertex should be one of the following 11 kinds
of possibilities: 1, 2, 3, 4, 5, 6, 7, 2 , 7 , 3 , 6 . Moreover,
every pair of adjacent vertices should be of the types in (5.65) and (5.66).
27. Duplij, Hong, Li 353
2. Except for 1, any type of action of Uq(sl(2)) on Aq(3) cannot be endowed
with two different vertices simultaneously, since the relations (2.2) acting on
x1 , x2 , x3 to produce zero cannot be satisfied.
3. If every vertex in the Dynkin diagram of sl(m+1) is endowed with an action
of Uq(sl(2)) on Aq(3) which is not of Case 1, any two vertices which are
not adjacent cannot be endowed with the types which are adjacent (5.65)
and (5.66).
Theorem 5.3. If m ≥ 4, all module-algebra structures of Uq(sl(m + 1)) =
H(ei, fi, k±1
i )1≤i≤m on Aq(3) when ki ∈ Aut L(Aq(3)) for i = 1, · · · , m are as
follows
ki(x1) = ±x1, ki(x2) = ±x2, ki(x3) = ±x3,
ei(x1) = ei(x2) = ei(x3) = fi(x1) = fi(x2) = fi(x3) = 0,
for any i ∈ {1, 2, · · · , m}.
For m = 3, all module-algebra structures of Uq(sl(4)) = H(ei, fi, k±1
i )i=1,2,3
on Aq(3) when ki ∈ Aut L(Aq(3)) for i = 1, 2, 3 are given by
(1)
ki(x1) = ±x1, ki(x2) = ±x2, ki(x3) = ±x3,
ei(x1) = ei(x2) = ei(x3) = fi(x1) = fi(x2) = fi(x3) = 0,
for any i ∈ {1, 2, 3}. All these module-algebra structures are not pairwise non-
isomorphic.
(2)
ki(x1) = qx1, ki(x2) = q−1
x2, ki(x3) = x3,
ei(x1) = 0, ei(x2) = c21x1, ei(x3) = 0,
fi(x1) = c−1
21 x2, fi(x2) = 0, fi(x3) = 0,
kj(x1) = q−2
x1, kj(x2) = q−1
x2, kj(x3) = q−1
x3,
ej(x1) = a1, ej(x2) = 0, ej(x3) = 0,
fj(x1) = −qa−1
1 x2
1, fj(x2) = −qa−1
1 x1x2, fj(x3) = −qa−1
1 x1x3,
ks(x1) = qx1, ks(x2) = qx2, ks(x3) = q2
x3,
es(x1) = −qb−1
3 x1x3, es(x2) = −qb−1
3 x2x3, es(x3) = −qb−1
3 x2
3,
fs(x1) = 0, fs(x2) = 0, fs(x3) = b3,
where a1 , b3 , c21 ∈ C{0} and i = 1, j = 2, s = 3 or i = 3, j = 2, s = 1. All
these module-algebra structures are isomorphic to that with a1 = b3 = c21 = 1.
29. Duplij, Hong, Li 355
Proof. First, we consider the case when m ≥ 5. By the above discussion, since
there are no paths in (5.66) whose length is larger than 4 and any two vertices
which are not adjacent in this path have no edge connecting them in (5.65) and
(5.66), the unique possibility of putting the actions of Uq(sl(2)) on the m vertices
in the Dynkin diagram is as follows:
1 1 · · · 1 1 .
Obviously, the above case determines the module-algebra structures of Uq(sl(m +
1)) on Aq(3).
Second, let us study the case when m = 3. By the above rules, and because
the Dynkin diagram of sl(4) is symmetric, we only need to check the following
cases
7 4 5 , 7 4 2 , 4 2 3 ,
4 5 3 , 4 5 6 , 2 3 5 ,
2 4 5 , 3 5 6 , 1 1 1 .
To determine the module-algebra structures of Uq(sl(4)) on Aq(3), we still have
to check the following equalities
k1e3(u) = e3k1(u), k1f3(u) = f3k1(u), k3e1(u) = e1k3(u), k3f1(u) = f1k3(u),
e1f3(u) = f3e1(u), e3f1(u) = f1e3(u), e1e3(u) = e3e1(u), f1f3(u) = f3f1(u),
for any u ∈ {x1, x2, x3}. For 7 4 5 , since k1e3(x3) = k1(b3x2) =
q2
b3x2 and e3k1(x3) = q−1
b3x2 , k1e3(x3) = e3k1(x3). Therefore, 7 4 5
is excluded. Similarly, we exclude 7 4 2 , 4 5 6 , and
3 5 6 . Moreover, it is easy to check the five remaining cases deter-
mine the module-algebra structures of Uq(sl(4)) on Aq(3).
Thirdly, we consider the case when m = 4. By the discussion above, we
only need to check the cases
7 4 2 3 , 7 4 5 3 ,
7 4 5 6 , 2 3 5 6 ,
1 1 1 1 .
Since the three adjacent vertices in the Dynkin diagram of sl(5) correspond to
one Hopf algebra isomorphic to Uq(sl(4)), by the results of the module-algebra
structures of Uq(sl(4)) on Aq(3), there is only one possibility:
1 1 1 1 .
Finally, we consider the isomorphism classes. Here, we will only show
that all the module-algebra structures of Uq(sl(4)) on Aq(3) in Case (2) are
isomorphic to that with a1 = c21 = b3 = 1. The desired isomorphism is given by
ψa1,c21,b3 : x1 → a1x1, x2 → a1c21x2, x3 → b3x3 . The other cases can be considered
similarly.
30. 356 Duplij, Hong, Li
Remark 5.4. By Theorem 5.3, the classical limits of the above actions, i.e. the
Lie algebra slm+1 -actions by differentiations on C[x1, x2, x3] can also be obtained,
as before.
Finally, we present a classification of Uq(sl(m + 1))-module algebra struc-
tures on Aq(2).
Since all module-algebra structures of Uq(sl(2)) on Aq(2) are presented in
[8], using the same method as above and by some computations, we can obtain
the following theorem.
Theorem 5.5. Uq(sl(3))-module algebra structures on Aq(2) up to isomor-
phisms and their classical limits are as follows:
Uq(sl(3))-module Classical limit
algebra structures sl3-actions on C[x1, x2]
ki(xs) = ±xs, kj(xs) = ±xs, hi(xs) = 0, hj(xs) = 0,
ei(xs) = 0, ej(xs) = 0, ei(xs) = 0, ej(xs) = 0,
fi(xs) = 0, fj(xs) = 0, fi(xs) = 0, fj(xs) = 0,
s ∈ {1, 2} s ∈ {1, 2}
ki(x1) = q−2
x1, ki(x2) = q−1
x2, hi(x1) = −2x1, hi(x2) = −x2,
kj(x1) = qx1, kj(x2) = q−1
x2, hj(x1) = x1, hj(x2) = −x2,
ei(x1) = 1, ei(x2) = 0, ei(x1) = 1, ei(x2) = 0,
ej(x1) = 0, ej(x2) = x1, ej(x1) = 0, ej(x2) = x1,
fi(x1) = −qx2
1, fi(x2) = −qx1x2, fi(x1) = −x2
, fi(x2) = −x1x2,
fj(x1) = x2, fj(x2) = 0 fj(x1) = x2, fj(x2) = 0
ki(x1) = qx1, ki(x2) = q2
x2, hi(x1) = x1, hi(x2) = 2x2,
kj(x1) = qx1, kj(x2) = q−1
x2, hj(x1) = x1, hj(x2) = −x2,
ei(x1) = −qx1x2, ei(x2) = −qx2
2, ei(x1) = −x1x2, ei(x2) = −x2
2,
ej(x1) = 0, ej(x2) = x1, ej(x1) = 0, ej(x2) = x1,
fi(x1) = 0, fi(x2) = 1, fi(x1) = 0, fi(x2) = 1,
fj(x1) = x2, fj(x2) = 0 fj(x1) = x2, fj(x2) = 0
ki(x1) = q−2
x1, ki(x2) = q−1
x2, hi(x1) = −2x1, hi(x2) = −x2,
kj(x1) = qx1, kj(x2) = q2
x2, hj(x1) = x1, hj(x2) = 2x2,
ei(x1) = 1, ei(x2) = 0, ei(x1) = 1, ei(x2) = 0,
ej(x1) = −qx1x2, ej(x2) = −qx2
2, ej(x1) = −x1x2, ej(x2) = −x2
2,
fi(x1) = −qx2
1, fi(x2) = −qx1x2, fi(x1) = −x2
1, fi(x2) = −x1x2,
fj(x1) = 0, fj(x2) = 1 fj(x1) = 0, fj(x2) = 1
for any i = 1, j = 2 or i = 2, j = 1. Note that there are no isomorphisms
between these four kinds of module-algebra structures.
Moreover, for any m ≥ 3, all module-algebra structures of Uq(sl(m + 1))
on Aq(2) are as follows:
ki(x1) = ±x1, ki(x2) = ±x2,
ei(x1) = ei(x2) = fi(x1) = fi(x2) = 0,
for any i ∈ {1, · · · , m}.
31. Duplij, Hong, Li 357
6. Uq(sl(m + 1))-module algebra structures on Aq(n) (n ≥ 4)
In this section, we will study the module algebra structures of Uq(sl(m + 1)) =
H(ei, fi, k±1
i )1≤i≤m on Aq(n) when ki ∈ AutL(Aq(n)) for i = 1, · · · , m and n ≥ 4.
By Theorem 3.1 and with a similar discussion in Section 4, we can obtain
the following proposition.
Proposition 6.1. For n ≥ 4, the module-algebra structures of Uq(sl(2)) on
Aq(n) are as follows:
(1) k(xi) = ±xi, e(xi) = f(xi) = 0,
for any i ∈ {1, · · · , n}. All these structures are pairwise nonisomorphic.
(2) k(xi) = qxi for ∀ i < j, k(xj) = q−2
xj, k(xi) = q−1
xi for ∀ i > j,
e(xi) = 0 for ∀ i = j, e(xj) = aj,
f(xi) = a−1
j xixj for ∀ i < j, f(xj) = −qa−1
j x2
j ,
f(xi) = −qa−1
j xjxi for ∀ i > j,
for any j ∈ {1, · · · , n} and aj ∈ C {0}. If j is fixed, then all of these structures
are isomorphic to that with aj = 1.
(3) k(xi) = qxi for ∀ i < j, k(xj) = q2
xj, k(xi) = q−1
xi for ∀ i > j,
e(xi) = −qb−1
j xixj for ∀ i < j, e(xj) = −qb−1
j x2
j ,
e(xi) = b−1
j xjxi for ∀ i > j, f(xi) = 0 for ∀ i = j, f(xj) = bj,
for any j ∈ {1, · · · , n} and bj ∈ C {0}. If j is fixed, then all of these structures
are isomorphic to that with bj = 1.
(4) k(xi) = xi for ∀ i < j, k(xj) = qxj,
k(xj+1) = q−1
xj+1, k(xi) = xi for ∀ i > j + 1,
e(xi) = 0 for ∀ i = j + 1, e(xj+1) = cj+1,jxj,
f(xi) = 0 for ∀ i = j, f(xj) = c−1
j+1,jxj+1,
for any j ∈ {1, · · · , n − 1} and cj+1,j ∈ C {0}. If j is fixed, then all of these
structures are isomorphic to that with cj+1,j = 1.
Remark 6.2. In Proposition 6.1 we have presented only the simplest module-
algebra structures. It is also complicated to give the solutions of (3.18) and (3.19)
for all cases. For example, by a very complex computation, we can obtain that
in Case
a1 0 · · · 0
0 0 · · · 0 0
,
0 0 · · · 0
0 0 · · · 0 1
, all Uq(sl(2))-module algebra
structures on Aq(n) are given by
32. 358 Duplij, Hong, Li
k(x1) = q−2
x1, k(xi) = q−1
xi for ∀ i > 1,
e(x1) = a1, e(xi) = 0 for ∀ i > 1,
f(x1) = −qa−1
1 x2
1,
f(x2) = −qa−1
1 x1x2 +
2<s≤n
v2s2x2x2
s +
2<s<k<l≤n
α22klx2xkxl + β22x3
2,
f(xi) = −qa−1
1 x1xi + (3)qβ22x2
2xi −
2<s<i≤n
q−1
(3)qv2s2x2
sxi
+
(2)q
(3)q
αn2inx2x2
i +
2<i<t≤n
v2t2xix2
t −
2<s<i<n
q−1
(2)qα22si
·xsx2
i +
q
(2)q
vnn2x2xixn +
2<k<i<n
αn2knx2xkxi
+
2<i<k<n
q
(3)q
αn2knx2xixk −
2<s<i<k≤n
α22skxsxixk
+
2<i<k<l≤n
α22klxixkxl −
2<s<k<i<n
q−1
(3)qα22skxsxkxi
−q−1
v2i2x3
i ,
where 2 < i < n,
f(xn) = −qa−1
1 x1xn + (3)qβ22x2
2xn −
2<s<n
q−1
(3)qv2s2x2
sxn
+vnn2x2x2
n −
2<k<n
q−1
(2)qα22knxkx2
n +
2<k<n
αn2knx2xkxn
−
2<s<k<n
q−1
(3)qα22skxsxkxn − q−1
v2n2x3
n,
where a1 ∈ C {0} and v2i2 , α22kl , β22 , vnn2 , αn2kn ∈ C.
Let us denote the module-algebra structures of Case (1), those in Case (2), Case
(3) and Case (4) in Proposition 6.1 by D, Aj , Bj and Cj respectively. For
determining the module-algebra structures of Uq(sl(3)) on Aq(n), we only need
to check whether (4.58)-(4.64) hold for any u ∈ {x1, · · · , xn}. For convenience,
we introduce a notation: if the actions of ks , es , fs are of the type Ai and the
actions of kt , et , ft are of the type Bj , they determine a module-algebra structure
of Uq(sl(3)) on Aq(n) for s = 1, t = 2 or s = 2, t = 1, then we say Ai and Bj are
compatible. By some computations, we can obtain that D and D are compatible,
Ai and Bj are compatible if and only if i = 1 and j = n, Ai and Cj are compatible
if and only if i = j, Bi and Cj are compatible if and only if j = i + 1, Ci and
Cj are compatible if and only if i = j + 1 or i = j − 1, and any two other cases
are not compatible. As before, we use two adjacent vertices to mean two classes
of module-algebra structures of Uq(sl(3)) on Aq(n).
Therefore, by the above discussion, similar to that in Section 5, we can
obtain the following proposition.
33. Duplij, Hong, Li 359
Proposition 6.3. For n ≥ 4, there are the module-algebra structures of Uq(sl(3))
on Aq(n) as follows:
D D , A1
TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT A2 · · · An−2 An−1
C1
AAAAAAAA C2
AAAAAAAAA
· · ·
EEEEEEEEE Cn−2
GGGGGGGGG
Cn−1
EEEEEEEE
B2 · · · Bn−2 Bn−1 Bn
.(6.67)
Here, every two adjacent vertices determine two classes of module-algebra struc-
tures of Uq(sl(3)) on Aq(n).
Then, for determining the module-algebra structures of Uq(sl(m + 1)) on
Aq(n), we have to find the pairs of vertices which are not adjacent in (6.67) and
satisfy the following relation: kiej(xs) = ejki(xs), kjei(xs) = eikj(xs), kifj(xs) =
fjki(xs), kjfi(xs) = fikj(xs), eiej(xs) = ejei(xs), eifj(xs) = fjei(xs), fifj(xs) =
fjfi(xs) where one vertex corresponds to the actions of ki , ei and fi and the other
vertex corresponds to the actions of kj , ej and fj , s ∈ {1, · · · , n}. It is easy to
check that Ai and Cj satisfy the above relations if and only if i < j or i > j + 1,
Bi and Cj satisfy the above relations if and only if i < j or i > j + 1, Ci and Cj
satisfy the above relations if and only if i = j + 1 or j = i + 1, and any other two
vertices do not satisfy the above relations.
We also use m adjacent vertices to mean two classes of the module-algebra
structures of Uq(sl(m + 1)) on Aq(n). For example,
Bn A1 C1 · · · Cm−2
determines two classes of the module-algebra structures of Uq(sl(m+1)) on Aq(n)
as follows: the one is that the actions of k1 , e1 , f1 are of the type Bn , those of
k2 , e2 , f2 are of the type A1 and those of ki , ei , fi are of the type Ci−2 for any
3 ≤ i ≤ m. The other is that the actions of ki , ei , fi are of the type Cm−1−i for
any 1 ≤ i ≤ m − 2, those of km−1 , em−1 , fm−1 are of the type A1 and those of
km , em , fm are of the type Bn .
Therefore, we obtain the following theorem.
Theorem 6.4. For m ≥ 3, n ≥ 4, the module-algebra structures of
Uq(sl(m + 1)) on Aq(n) are as follows:
D D · · · D
m
, (6.68)
Ai Ci · · · Ci+m−2 , (6.69)
Ci Ci+1 · · · Ci+m−2 Bi+m−1 , (6.70)
Ci Ci+1 · · · Ci+m−1 , (6.71)
A1 Bn Cn−1 · · · Cn+2−m , (6.72)
34. 360 Duplij, Hong, Li
where n + 2 − m > 1,
Bn A1 C1 · · · Cm−2 , (6.73)
where m − 2 < n − 1.
Here, every such diagram corresponds to two classes of the module-algebra
structures of Uq(sl(m + 1)) on Aq(n).
Remark 6.5. When m = n − 1 and the indexes of the vertices of the Dynkin
diagram are given 1, · · · , n − 1 from the left to the right, the actions correspond
to (6.71), i.e., C1 C2 · · · Cn−1 is the case discussed in [15]. In
addition, we are sure that when m ≥ n + 1, all the module-algebra structures of
Uq(sl(m + 1)) on Aq(n) are of the type in (6.68), since there are no paths whose
length is larger than n + 1 and any two vertices which are not adjacent in this
path have no edge connecting them in (6.67). The detailed proof may be similar
to that in Section 5. Moreover, the module-algebra structures of the quantum
enveloping algebras corresponding to the other semisimple Lie algebras on Aq(n)
can be considered in the same way.
Acknowledgments. The first author (S.D.) is grateful to L. Carbone, J. Cuntz,
P. Etingof, and E. Karolinsky for discussions, and to the Alexander von Humboldt
Foundation for funding his research stay at the University of M¨unster in 2014,
where this work was finalized.
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Steven Duplij
Mathematisches Institute
Universit¨at M¨unster
Einsteinstr. 62
48149 M¨unster, Germany
duplijs@math.uni-muenster.de
Yanyong Hong
Zhejiang Agriculture and Forestry
University
Hangzhou, 311300, P.R.China
Zhejiang University
Hangzhou, 310027, P.R.China
hongyanyong2008@yahoo.com
Fang Li
Department of Mathematics
Zhejiang University
Hangzhou, 310027, P.R.China
fangli@zju.edu.cn
Received March 14, 2014
and in final form July 4, 2014