This document discusses linear logic and its relationship to constructive mathematics. It begins by providing background on intuitionistic logic, classical logic, and the Brouwer-Heyting-Kolmogorov interpretation of intuitionistic connectives. It then introduces linear logic and discusses how linear logic can provide a better account of negation and proofs by contradiction for constructive mathematics. The document explores models of linear logic using Heyting algebras and the dialectica construction. It considers how linear logic may help explain traditionally non-constructive ideas in mathematics.
Talk at the Melbourne Logic Seminar
on Shawn Standefer invitation
Dialectica categories for the Lambek calculus
Valeria de Paiva
The Topos Institute, Berkeley, CA
Abstract:
Dialectica categorical models of the Lambek Calculus were first presented in the Amsterdam Colloquium a long time ago. Following Lambek's lead, we approached the Lambek Calculus from the perspective of Linear Logic and adapted the Dialectica categorical models for Linear Logic to Lambek's non-commutative calculus. The old work took for granted the syntax of the Lambek calculus and only discussed the exciting possibilities of new models for the modalities that Linear Logic introduced. Many years later we find that the work on dialectica models of the Lambek calculus is still interesting and that it might inform some of the most recent work on the relationship between Categorial Grammars and notions of Distributional Semantics.
Thus we revisited the old work, making sure that the syntax details that were sketchy on the first version got completed and verified, using automated tools such as Agda and Ott. Ultimately we are interested in the applicability of the original systems to their intended uses in the construction of semantics of Natural Language. But before we can discuss it, we need to make sure that the mathematical properties that make the Lambek calculus attractive are all properly modeled and this is the main aim of this paper.
We recall the Lambek calculus with its Curry-Howard isomorphic term assignment system. We extend it with a $\kappa$ modality, inspired by Yetter's work, which makes the calculus commutative. Then we add the of-course modality $!$, as Girard did, re-introducing weakening and contraction for all formulas and get back the full power of intuitionistic and classical logic. We also present algebraic semantics and categorical semantics, proved sound and complete for the whole system. Finally, we show the traditional properties of type systems, like subject reduction, the Church-Rosser theorem and normalization for the calculi of extended modalities, which we did not have before.
Talk at the Melbourne Logic Seminar
on Shawn Standefer invitation
Dialectica categories for the Lambek calculus
Valeria de Paiva
The Topos Institute, Berkeley, CA
Abstract:
Dialectica categorical models of the Lambek Calculus were first presented in the Amsterdam Colloquium a long time ago. Following Lambek's lead, we approached the Lambek Calculus from the perspective of Linear Logic and adapted the Dialectica categorical models for Linear Logic to Lambek's non-commutative calculus. The old work took for granted the syntax of the Lambek calculus and only discussed the exciting possibilities of new models for the modalities that Linear Logic introduced. Many years later we find that the work on dialectica models of the Lambek calculus is still interesting and that it might inform some of the most recent work on the relationship between Categorial Grammars and notions of Distributional Semantics.
Thus we revisited the old work, making sure that the syntax details that were sketchy on the first version got completed and verified, using automated tools such as Agda and Ott. Ultimately we are interested in the applicability of the original systems to their intended uses in the construction of semantics of Natural Language. But before we can discuss it, we need to make sure that the mathematical properties that make the Lambek calculus attractive are all properly modeled and this is the main aim of this paper.
We recall the Lambek calculus with its Curry-Howard isomorphic term assignment system. We extend it with a $\kappa$ modality, inspired by Yetter's work, which makes the calculus commutative. Then we add the of-course modality $!$, as Girard did, re-introducing weakening and contraction for all formulas and get back the full power of intuitionistic and classical logic. We also present algebraic semantics and categorical semantics, proved sound and complete for the whole system. Finally, we show the traditional properties of type systems, like subject reduction, the Church-Rosser theorem and normalization for the calculi of extended modalities, which we did not have before.
Benchmarking Linear Logic Proofs, Valeria de PaivaValeria de Paiva
Talk at the 1st Joint Meeting Brazil-France in Mathematics, https://impa.br/eventos-do-impa/eventos-2019/1st-joint-meeting-brazil-france-in-mathematics/
Talk for the women+@DCS Sheffield University, UK
Title: Natural Language Inference for Humans
Valeria de Paiva,
Topos Institute, Berkeley, USA
Abstract: One hears much about the incredible results of recent neural nets methods in NLP. In particular much has been made of the results on the Natural Language Inference task using the huge new corpora SNLI, MultiNLI, SciTail, etc, constructed since 2015. Wanting to join in the fun, we decided to check the results on the corpus SICK (Sentences Involving Compositional Knowledge), which is two orders of magnitude smaller than SLNI and presumably easier to deal with.
We discovered that there were many results that did not agree with our intuitions. As a result, we have written so far five papers on the subject (with another one submitted to COLING2020).
I want to show you a potted summary of this work, to explain why we think this work is not near completion yet and how we're planning to tackle it.
This is work with Katerina Kalouli, Livy Real, Annebeth Buis and Martha Palmer. The papers are
Explaining Simple Natural Language Inference. Proceedings of the 13th Linguistic Annotation Workshop (LAW 2019), 01 August 2019. ACL 2019,
WordNet for “Easy” Textual Inferences. Proceedings of the Globalex Workshop, associated with LREC 2018
Graph Knowledge Representations for SICK. informal Proc of 5th Workshop on Natural Language and Computer Science, Oxford, UK, 08 July 2018
Textual Inference: getting logic from humans. Proc of the 12th International Conference on Computational Semantics (IWCS), 22 September 2017
Correcting Contradictions. Proc of Computing Natural Language Inference Workshop (CONLI 2017) @IWCS 2017
Benchmarking Linear Logic Proofs, Valeria de PaivaValeria de Paiva
Talk at the 1st Joint Meeting Brazil-France in Mathematics, https://impa.br/eventos-do-impa/eventos-2019/1st-joint-meeting-brazil-france-in-mathematics/
Talk for the women+@DCS Sheffield University, UK
Title: Natural Language Inference for Humans
Valeria de Paiva,
Topos Institute, Berkeley, USA
Abstract: One hears much about the incredible results of recent neural nets methods in NLP. In particular much has been made of the results on the Natural Language Inference task using the huge new corpora SNLI, MultiNLI, SciTail, etc, constructed since 2015. Wanting to join in the fun, we decided to check the results on the corpus SICK (Sentences Involving Compositional Knowledge), which is two orders of magnitude smaller than SLNI and presumably easier to deal with.
We discovered that there were many results that did not agree with our intuitions. As a result, we have written so far five papers on the subject (with another one submitted to COLING2020).
I want to show you a potted summary of this work, to explain why we think this work is not near completion yet and how we're planning to tackle it.
This is work with Katerina Kalouli, Livy Real, Annebeth Buis and Martha Palmer. The papers are
Explaining Simple Natural Language Inference. Proceedings of the 13th Linguistic Annotation Workshop (LAW 2019), 01 August 2019. ACL 2019,
WordNet for “Easy” Textual Inferences. Proceedings of the Globalex Workshop, associated with LREC 2018
Graph Knowledge Representations for SICK. informal Proc of 5th Workshop on Natural Language and Computer Science, Oxford, UK, 08 July 2018
Textual Inference: getting logic from humans. Proc of the 12th International Conference on Computational Semantics (IWCS), 22 September 2017
Correcting Contradictions. Proc of Computing Natural Language Inference Workshop (CONLI 2017) @IWCS 2017
ZGB - The Role of Generative AI in Government transformation.pdfSaeed Al Dhaheri
This keynote was presented during the the 7th edition of the UAE Hackathon 2024. It highlights the role of AI and Generative AI in addressing government transformation to achieve zero government bureaucracy
Understanding the Challenges of Street ChildrenSERUDS INDIA
By raising awareness, providing support, advocating for change, and offering assistance to children in need, individuals can play a crucial role in improving the lives of street children and helping them realize their full potential
Donate Us
https://serudsindia.org/how-individuals-can-support-street-children-in-india/
#donatefororphan, #donateforhomelesschildren, #childeducation, #ngochildeducation, #donateforeducation, #donationforchildeducation, #sponsorforpoorchild, #sponsororphanage #sponsororphanchild, #donation, #education, #charity, #educationforchild, #seruds, #kurnool, #joyhome
Russian anarchist and anti-war movement in the third year of full-scale warAntti Rautiainen
Anarchist group ANA Regensburg hosted my online-presentation on 16th of May 2024, in which I discussed tactics of anti-war activism in Russia, and reasons why the anti-war movement has not been able to make an impact to change the course of events yet. Cases of anarchists repressed for anti-war activities are presented, as well as strategies of support for political prisoners, and modest successes in supporting their struggles.
Thumbnail picture is by MediaZona, you may read their report on anti-war arson attacks in Russia here: https://en.zona.media/article/2022/10/13/burn-map
Links:
Autonomous Action
http://Avtonom.org
Anarchist Black Cross Moscow
http://Avtonom.org/abc
Solidarity Zone
https://t.me/solidarity_zone
Memorial
https://memopzk.org/, https://t.me/pzk_memorial
OVD-Info
https://en.ovdinfo.org/antiwar-ovd-info-guide
RosUznik
https://rosuznik.org/
Uznik Online
http://uznikonline.tilda.ws/
Russian Reader
https://therussianreader.com/
ABC Irkutsk
https://abc38.noblogs.org/
Send mail to prisoners from abroad:
http://Prisonmail.online
YouTube: https://youtu.be/c5nSOdU48O8
Spotify: https://podcasters.spotify.com/pod/show/libertarianlifecoach/episodes/Russian-anarchist-and-anti-war-movement-in-the-third-year-of-full-scale-war-e2k8ai4
Presentation by Jared Jageler, David Adler, Noelia Duchovny, and Evan Herrnstadt, analysts in CBO’s Microeconomic Studies and Health Analysis Divisions, at the Association of Environmental and Resource Economists Summer Conference.
Jennifer Schaus and Associates hosts a complimentary webinar series on The FAR in 2024. Join the webinars on Wednesdays and Fridays at noon, eastern.
Recordings are on YouTube and the company website.
https://www.youtube.com/@jenniferschaus/videos
Canadian Immigration Tracker March 2024 - Key SlidesAndrew Griffith
Highlights
Permanent Residents decrease along with percentage of TR2PR decline to 52 percent of all Permanent Residents.
March asylum claim data not issued as of May 27 (unusually late). Irregular arrivals remain very small.
Study permit applications experiencing sharp decrease as a result of announced caps over 50 percent compared to February.
Citizenship numbers remain stable.
Slide 3 has the overall numbers and change.
Up the Ratios Bylaws - a Comprehensive Process of Our Organizationuptheratios
Up the Ratios is a non-profit organization dedicated to bridging the gap in STEM education for underprivileged students by providing free, high-quality learning opportunities in robotics and other STEM fields. Our mission is to empower the next generation of innovators, thinkers, and problem-solvers by offering a range of educational programs that foster curiosity, creativity, and critical thinking.
At Up the Ratios, we believe that every student, regardless of their socio-economic background, should have access to the tools and knowledge needed to succeed in today's technology-driven world. To achieve this, we host a variety of free classes, workshops, summer camps, and live lectures tailored to students from underserved communities. Our programs are designed to be engaging and hands-on, allowing students to explore the exciting world of robotics and STEM through practical, real-world applications.
Our free classes cover fundamental concepts in robotics, coding, and engineering, providing students with a strong foundation in these critical areas. Through our interactive workshops, students can dive deeper into specific topics, working on projects that challenge them to apply what they've learned and think creatively. Our summer camps offer an immersive experience where students can collaborate on larger projects, develop their teamwork skills, and gain confidence in their abilities.
In addition to our local programs, Up the Ratios is committed to making a global impact. We take donations of new and gently used robotics parts, which we then distribute to students and educational institutions in other countries. These donations help ensure that young learners worldwide have the resources they need to explore and excel in STEM fields. By supporting education in this way, we aim to nurture a global community of future leaders and innovators.
Our live lectures feature guest speakers from various STEM disciplines, including engineers, scientists, and industry professionals who share their knowledge and experiences with our students. These lectures provide valuable insights into potential career paths and inspire students to pursue their passions in STEM.
Up the Ratios relies on the generosity of donors and volunteers to continue our work. Contributions of time, expertise, and financial support are crucial to sustaining our programs and expanding our reach. Whether you're an individual passionate about education, a professional in the STEM field, or a company looking to give back to the community, there are many ways to get involved and make a difference.
We are proud of the positive impact we've had on the lives of countless students, many of whom have gone on to pursue higher education and careers in STEM. By providing these young minds with the tools and opportunities they need to succeed, we are not only changing their futures but also contributing to the advancement of technology and innovation on a broader scale.
Many ways to support street children.pptxSERUDS INDIA
By raising awareness, providing support, advocating for change, and offering assistance to children in need, individuals can play a crucial role in improving the lives of street children and helping them realize their full potential
Donate Us
https://serudsindia.org/how-individuals-can-support-street-children-in-india/
#donatefororphan, #donateforhomelesschildren, #childeducation, #ngochildeducation, #donateforeducation, #donationforchildeducation, #sponsorforpoorchild, #sponsororphanage #sponsororphanchild, #donation, #education, #charity, #educationforchild, #seruds, #kurnool, #joyhome
What is the point of small housing associations.pptxPaul Smith
Given the small scale of housing associations and their relative high cost per home what is the point of them and how do we justify their continued existance
What is the point of small housing associations.pptx
Linear Logic and Constructive Mathematics, after Shulman
1. 1/35
Introduction
BHK
Algebra
Constructivism
Linear Logic and Constructive Mathematics
(Algebraic Dialectica for Logicians)
Valeria de Paiva
Topos Institute
21 de abril de 2021
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
3. 3/35
Introduction
BHK
Algebra
Constructivism
The courage of our convictions
This discussion is mostly based on reading Mike Shulman’s ‘Linear
Logic for Constructive Mathematics’. I am grateful to Mike for
ideas and even slides. (the mistakes are my own, of course)
I want to talk about an algebraic version of the dialectica
construction, but to do that first
classical vs. intuitionistic logic
intuitionistic vs. linear logic
linear mathematics?
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
4. 3/35
Introduction
BHK
Algebra
Constructivism
The courage of our convictions
This discussion is mostly based on reading Mike Shulman’s ‘Linear
Logic for Constructive Mathematics’. I am grateful to Mike for
ideas and even slides. (the mistakes are my own, of course)
I want to talk about an algebraic version of the dialectica
construction, but to do that first
classical vs. intuitionistic logic
intuitionistic vs. linear logic
linear mathematics?
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
5. 3/35
Introduction
BHK
Algebra
Constructivism
The courage of our convictions
This discussion is mostly based on reading Mike Shulman’s ‘Linear
Logic for Constructive Mathematics’. I am grateful to Mike for
ideas and even slides. (the mistakes are my own, of course)
I want to talk about an algebraic version of the dialectica
construction, but to do that first
classical vs. intuitionistic logic
intuitionistic vs. linear logic
linear mathematics?
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
7. 5/35
Introduction
BHK
Algebra
Constructivism
A Hundred Years Ago
Hilbert (1927) ”To prohibit existence statements and the principle
of excluded middle is tantamount to relinquishing the science of
mathematics altogether.”Brouwer-Hilbert controversy (from
wikipedia)
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
9. 7/35
Introduction
BHK
Algebra
Constructivism
More than Thirty Years Ago
Girard shook the basis of logic several times
“Broccoli logic”is still one of enduring jokes in the internet
Linear Logic has been very influential
Out of fashion now?
Linear thinking and variations permeated logic and theoretical
computing
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
10. 8/35
Introduction
BHK
Algebra
Constructivism
Categorical Proof Theory
Types are formulae/objects in appropriate category,
Terms/programs are proofs/morphisms in the category,
Logical constructors are appropriate categorical constructions.
Most important: Reduction is proof normalization (Tait)
Outcome: Transfer results/tools from logic to CT to CSci
How far can we push it?
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
12. 10/35
Introduction
BHK
Algebra
Constructivism
papers: Term calculus for intuitionistic linear logic (BBdePH1993),
Term assignment for ILL (TR1992) and Linear λ-calculus and
categorical models revisited (CSL1992)
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
14. 12/35
Introduction
BHK
Algebra
Constructivism
Intuitionistic Logic
Brouwer wanted to eliminate non-constructive proofs. Heyting
formulated intuitionistic logic where all valid proofs are necessarily
constructive. Kolmogorov, Glivenko, Weyl, Bishop, and many
others developed constructive maths
http://dx.doi.org/10.1090/bull/1556 FIVE
STAGES OF ACCEPTING CONSTRUCTIVE MATHEMATICS
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
15. 13/35
Introduction
BHK
Algebra
Constructivism
Intuitionistic Logic
Proof by contradiction is not allowed
a statement can be ’not false’ without being true: ¬¬P does
not imply P
De Morgan’s laws hold* except ¬(P ∧ Q) → (¬P ∨ ¬Q)
Similarly,¬∀x.P(x) does not imply ∃x.¬P(x)
The law of excluded middle P ∨ ¬P does not hold in general
The three connectives ∧, ∨, → are independent: neither can
be defined in terms of the others
Negation is a defined connective ¬A := A → ⊥
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
16. 14/35
Introduction
BHK
Algebra
Constructivism
Brouwer-Heyting-Kolmogorov (BHK) interpretation
This an informal description of the meanings of intuitionistic
connectives in terms of what counts as a proof of them
A proof of P ∧ Q is a proof of P and a proof of Q
A proof of P ∨ Q is a proof of P or a proof of Q (plus a
marker of which one it is)
A proof of P → Q is a construction transforming any proof of
P into a proof of Q
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
17. 15/35
Introduction
BHK
Algebra
Constructivism
BHK interpretation of Negation
Intuitionism defines ¬P to be P → ⊥,
A proof of ¬P is a construction transforming any proof of P
into a proof of a contradiction.
This explains the properties of negation in intuitionistic logic:
If it would be contradictory to have a construction
transforming any proof of P into a contradiction, it does not
follow that we have a proof of P. Hence ¬¬P does not imply
P
For an arbitrary P, we can not claim to have either a proof of
P or a construction transforming any proof of P into a
contradiction. (E.g. P might be the Riemann hypothesis.) So
P ∨ ¬P does not hold.
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
18. 16/35
Introduction
BHK
Algebra
Constructivism
Is there a better Negation?
Girard’s idea: formal de Morgan dual, the negation in LL
¬(P ∨ Q) =def ¬P ∧ ¬Q
¬(P ∧ Q) =def ¬P ∨ ¬Q
¬∃x.P(x) =def ∀x.¬P(x)
¬∀x.P(x) =def ∃x.¬P(x)
A constructive proof of ∃x.P(x) must provide an example
A constructive disproofof ∀x.P(x) should provide a
counterexample
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
19. 17/35
Introduction
BHK
Algebra
Constructivism
Is there a better Negation?
Shulman’s bold idea: LL’s involutive negation solves many of
the issues of intuitionistic negation in mathematics
To prove ∃x.P(x) by contradiction, we assume its negation
∀x.¬P(x). But in order to use this hypothesis at all, we have
to apply it to some x! we are necessarily constructing
something.
Hence an involutive negation makes proofs by contradiction
less objectionable
Moreover, he produces examples showing that traditional uses
of non-constructivity are disallowed and that convoluted ideas
like ’apartness’ can be better explained in linear terms
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
20. 18/35
Introduction
BHK
Algebra
Constructivism
Linear Logic for Constructive Mathematics
We divide the hypotheses into linear and nonlinear ones. The
linear ones can only be used once in the course of a proof.
All ‘hypotheses for contradiction’ in a proof by contradiction
are linear hypotheses.
Similarly, P −◦ Q is a linear implication that uses P only once.
It is contraposable, ¬(P −◦ Q) = (¬Q −◦ ¬P) (here we’re
talking about bi-implications)
Linearity is the default status of assertions. We mark the
nonlinear hypotheses with a modality, !P.
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
21. 19/35
Introduction
BHK
Algebra
Constructivism
Not so classical disjunctions
In classical logic, (P ∨ Q) = (¬P → Q) = (¬Q → P).
This is no longer true in intuitionistic logic. (connectives are
independent)
It also fails in linear logic for the ‘constructive’ disjunction ∨.
classical Linear Logic does have (¬P −◦ Q) = (¬Q −◦ P),
defining another kind of disjunction that is weaker than ∨.
in classical linear logic P ` Q = (¬P −◦ Q) = (¬Q −◦ P).
in CLL ∨-excluded middle P ∨ ¬P fails. But par-excluded
middle (P ` ¬P) = (¬P −◦ ¬P) is a tautology.
∨ supports proof by cases; ` supports the disjunctive
syllogism
in FILL no excluded middle, 5 independent connectives
Still the case that ”For an arbitrary P, we can not claim to
have either a proof of P or a construction transforming any
proof of P into a contradiction.”
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
22. 20/35
Introduction
BHK
Algebra
Constructivism
BHK for Linear Logic
The BHK interpretation privileges proofs over refutations.
A proof of P ∧ Q is a proof of P and a proof of Q. A
refutation of P ∧ Q is a refutation of P or a refutation of Q
A proof of P ∨ Q is a proof of P or a proof of Q. A refutation
of P ∨ Q is a refutation of P and a refutation of Q.
A proof of P ` Q is a construction transforming any
refutation of P into a proof of Q, and any refutation of Q
into a proof of P. A refutation of P ` Q is a refutation of P
and a refutation of Q.
A proof of P −◦ Q is a construction transforming any proof of
P into a proof of Q, and a construction transforming any
refutation of Q into a refutation of P. A refutation of P −◦ Q
is a proof of P and a refutation of Q.
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
23. 21/35
Introduction
BHK
Algebra
Constructivism
Making this BHK more formal?
Shulman’s sections: intuitionistic logic, linear logic, the
standard interpretation, the hidden linear nature of
constructive mathematics
I cannot judge how good the linear logic modifications are for
constructive mathematics, but I do have issues with what he
calls the ’standard interpretation’. The Dialecica version over
a Heyting algebra H and 0 is as good as the Chu construction
Mike says ‘If constructive logic is the logic of affirmative
propositions, then affine logic is the logic of propositions that
are subject to both affirmation and refutation, and the Chu
construction is the canonical embedding of the former in the
latter. Why canonical?
‘in the Dialectica interpretation the forwards and backwards
information is explicitly carried by functions, rather than
proofs as in the Chu construction.’ hmm?
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
24. 22/35
Introduction
BHK
Algebra
Constructivism
Heyting algebras
Definition
A Heyting algebra is a cartesian closed lattice, i.e. a poset (H, ≤)
with
A top element > and bottom element ⊥,
Meets P ∧ Q and joins P ∨ Q,
An ’implication’ with (P ∧ Q) ≤ R iff P ≤ (Q → R)
Heyting algebras are the algebraic semantics of intuitionistic
propositional logic, just like Boolean algebras are for classical logic.
For algebraic semantics of CLL/ILL/FILL a bit more complicated. I
talked about lineales, which are simply posetal symmetric
monoidal closed categories. Shulman wants to force units of tensor
and product to be the same
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
25. 23/35
Introduction
BHK
Algebra
Constructivism
Dejà vu?
Theorem (de Paiva CTCS1989)
For any Heyting algebra H, consider the algebra Dial⊥(H):
Elements are pairs P = (P+, P−) where P+, P− ∈ H and
P+ ∧ P− = ⊥. (Think P+ = proofs, P− = refutations)
Define P ≤ Q to mean (P+ ≤ Q+ and Q− ≤ P−)
P ∧ Q = (P+ ∧ Q+, P− ∨ Q−) and
P ∨ Q = (P+ ∨ Q+, P− ∧ Q−) and > = (>, ⊥) and
⊥ = (⊥, >)
P ⊗ Q = (P+ ∧ Q+, (P+ → Q−) ∧ (Q+ → P−))
P ` Q = ((P+ → Q+) ∧ (Q+ → P+), P− ∧ Q−)
P −◦ Q = ((P+ → Q+) ∧ (Q− → P−), P+ ∧ Q−)
Then Dial⊥(H) is a model of Linear Logic (without exponentials).
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
26. 24/35
Introduction
BHK
Algebra
Constructivism
Bang Modality
Digression: The other theorem of CTCS1989...
For any Heyting algebra H which has free co-commutative monoids
we can define a !-comonad that makes Dial⊥(H) is a model of IL.
Too complicated?
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
27. 25/35
Introduction
BHK
Algebra
Constructivism
Back to constructivism: Mike says
Girard was interested in Proof nets, Geometry of Interactions,
Games, Ludics, etc Linear logicians were interested in having both
LL and IL, constructivists use DTT
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
34. 32/35
Introduction
BHK
Algebra
Constructivism
Intuition for Dialectica objects?
Blass makes the case for thinking of problems in computational
complexity. Intuitively an object of the dialectica construction
A = (U, X, α)
can be seen as representing a problem.
The elements of U are instances of the problem, while the
elements of X are possible answers to the problem instances.
The relation α says whether the answer is correct for that instance
of the problem or not.
LL4CM only considers objects of the form (P+, P−) of proofs and
refutations, the relation is always contradiction ⊥. Presumably
sometimes one wants to have different relations...
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
35. 33/35
Introduction
BHK
Algebra
Constructivism
Examples of objects in Dialectica
1. The object (N, N, =) where n is related to m iff n = m.
2. The object (NN, N, α) where f is α-related to n iff f (n) = n.
3. The object (R, R, ≤) where r1 and r2 are related iff r1 ≤ r2
4. The objects (2, 2, =) and (2, 2, 6=) with usual equality and
inequality.
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
36. 34/35
Introduction
BHK
Algebra
Constructivism
Conclusions
Introduced you to Shulman’s bold idea of doing constructive
mathematics with linear logic.
Don’t see the canonicity of Chu’s construction.
Believe FILL and Dial⊥(H) work just as well and have an
associated linear λ-calculus
Hinted at its importance for interdisciplinarity:
Category Theory, Proofs and Programs
Much more work needed for applications, LinearLean anyone? In
particular work needed on connecting LL+IL with classical logic.
Ecumenical logic ftw!
Thank you!
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics
37. 35/35
Introduction
BHK
Algebra
Constructivism
Some References
N.Benton, A mixed linear and non-linear logic: Proofs, terms and models.
Computer Science Logic, CSL, (1994).
A.Blass, Questions and Answers: A Category Arising in Linear Logic,
Complexity Theory, and Set Theory, Advances in Linear Logic, London
Math. Soc. Lecture Notes 222 (1995).
de Paiva, The Dialectica Categories, Technical Report, Computer Lab,
University of Cambridge, number 213, (1991).
de Paiva, A dialectica-like model of linear logic, Category Theory and
Computer Science, Springer, (1989) 341–356.
de Paiva, The Dialectica Categories, In Proc of Categories in Computer
Science and Logic, Boulder, CO, 1987. Contemporary Mathematics, vol
92, American Mathematical Society, 1989 (eds. J. Gray and A. Scedrov)
Valeria de Paiva Topos Institute Linear Logic and Constructive Mathematics