The study sheds light on the two-fuzzy normed space concentrating on some of their properties like convergence, continuity and the in order to study the relationship between these spaces
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Β
Properties of Two-Fuzzy Normed Spaces
1. IOSR Journal of Mathematics (IOSR-JM)
e-ISSN: 2278-5728,p-ISSN: 2319-765X, Volume 7, Issue 2 (Jul. - Aug. 2013), PP 30-34
www.iosrjournals.org
www.iosrjournals.org 30 | Page
Some properties of two-fuzzy Nor med spaces
Noori F.AL-Mayahi, Layth S.Ibrahaim
1
(Department of Mathematics ,College of Computer Science and Mathematics ,University of AL βQadissiya)
2
(Department of Mathematics ,College of Computer Science and Mathematics ,University of AL βQadissiya)
Abstract: The study sheds light on the two-fuzzy normed space concentrating on some of their properties like
convergence, continuity and the in order to study the relationship between these spaces
Keywords: fuzzy set, Two-fuzzy normed space, Ξ±-norm,
2010 MSC: 46S40
I. Introduction
The concept of fuzzy set was introduced by Zadeh [2] in 1965 as an extension of the classical notion of
set. A satisfactory theory of 2-norm on a linear space has been introduced and developed by Gahler in [4]. The
concept of fuzzy norm and πΌ β ππππ were introduced by Bag and Samanta and the notions of convergent and
Cauchy sequences were also discussed in [6]. zhang [1] has defined fuzzy linear space in a different way. RM.
Somasundaram and ThangarajBeaula defined the notion of fuzzy 2-normed linear space (F(X);N) or 2- fuzzy 2-
normed linear space. Some standard results in fuzzy 2- normed linear spaces were extended .The famous closed
graph theorem and Riesz Theorem were also established in 2-fuzzy 2-normed linear space. In [5] , we have
introduced the new concept of 2-fuzzy inner product space on F(X), the set of all fuzzy sets of X. This paper is
about the concepts related to two-fuzzy normed spaces (fuzzy convergence and fuzzy continuity).
II. PRELIMINARIES
Definition2.1.[3]Let X be a real vector space of dimension greater than one and let . , . be a real valued
function on X Γ X satisfying the following conditions:
(1) π₯, π¦ = 0 if and only if x and y are linearly dependent,
(2) π₯, π¦ = π¦, π₯
(3) πΌπ₯, π¦ = |π| π₯, π¦ π€ππππ πΌ ππ ππππ,
(4) π₯, π¦ + π§ < π₯, π¦ + π₯, π§
. , . is called a two-norm on X and the pair (π, . , . ) is called a two normed liner space.
Definition2.2.[3]Let X be a vector space over K (the field of real or complex numbers). A fuzzy subset N of
π Γ β (β, the set of real numbers) is called a fuzzy norm on X if and only if for all
π₯, π¦ β π πππ π β πΎ.
(N1) For all π‘ β β π€ππ‘π π‘ β€ 0, π(π₯, π‘) = 0
(N2) For all π‘ β β π€ππ‘π π‘ > 0, π(π₯, π‘) = 1 ππ πππ ππππ¦ ππ π₯ = 0
(N3) For all π‘ β β π€ππ‘π π‘ > 0, π ππ₯, π‘ = π π₯, πΆ = π π₯,
π₯
π
, ππ π = 0
(N4) For all π , π‘ β β , π₯, π¦ β π, π(π + π, π + π‘) > πππ{π(π₯, π ), π(π¦, π‘)}
(N5) π π₯, . is a non decreasing function of β and N(x, t)tββ
lim
= 1
The pair (π, π) will be referred to be as a fuzzy normed linear space.
Theorem2.3.[3]Let (π, π) be a fuzzy normed linear space . Assume ππ’ππ‘πππ π‘πππ‘ (π6) π(π₯, π‘) >
0 πππ πππ π‘ > 0 πππππππ π₯ = 0.
Define π₯ πΌ = πππ{π‘ βΆ π(π₯, π‘) > πΌ} π€ππππ πΌ β (0,1).
Then { π₯ πΌ βΆ πΌ β (0, 1)} is an ascending family of norms on X (or) Ξ± β norms on π
corresponding to the fuzzy norm on π.
Definition2.4.[3]A fuzzy vector space π = π Γ (0,1]over the number field K, where the addition and scalar
multiplication operation on π are defined by
(π₯, π) + (π¦, π) = (π₯ + π¦, π β π) πππ π(π₯, π) = (ππ₯, π)
is a fuzzy normed space if to every (π₯, π) β πthere is associated a non-negative real number, (π₯, π) , called
the fuzzy norm of (π₯, π), in such a way that
(1) (π₯, π) = 0 πππ π₯ = 0 π‘ππ π§πππ πππππππ‘ ππ π, π β (0,1]
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(2) (ππ₯, π) = |π| (π₯, π) , πππ πππ (π₯, π) β π πππ πππ π πΊ πΎ
(3) π₯, π + π¦, π < π₯, π β π + π¦, π β π πππ πππ π₯, π πππ
(π¦, π) β π
(4) π(π₯, βππ‘) = β (π₯, ππ‘ ) πππ ππ‘ β (0,1]
Let π be a nonempty and πΉ(π)be the set of all fuzzy sets in X. If
π β πΉ(π) π‘πππ π = { π₯, π : π₯ β π πππ π β (0,1]}. Clearly f is a bounded
function for π (π₯) β€ 1 . Let K be the space of real numbers, then F(X) is a linear space over the field K
where the addition and scalar multiplication are defined by
π + π = π₯, π + π¦, π = {(π₯ + π£, πβπ): (π₯, π) β π, πππ (π¦, π) β π}
ππ = { ππ, π :(π₯, π) β π} π€ππππ π β πΎ. The linear space πΉ(π) is said to be normed space if to everyπ β
πΉ(π), there is associated a non-negative real number π called the norm of f in such a way that
(1) π = 0 ππ πππ ππππ¦ ππ π = 0 For,
π = 0 β { π₯, π : (π₯, π) β π} = 0
β π₯ = 0, π β 0,1
β π = 0.
(2) ππ = π π , π β πΎ For,
ππ = { ππ₯, π : π₯, π β π, π β πΎ }
= { π π₯, π : π₯, π β π } =|π| π
(3) π + π β€ π + π πππ ππ£πππ¦ π, π β πΉ(π)
For, π + π = { (π₯, π) + (π¦, π) /π₯, π¦ β π, π, π β (0,1]}
= { (π₯ + π¦), πβπ : π₯, π¦ β π, π, π β (0,1]}
β€ { π₯, π + π¦, πβπ :(π₯, π) β ππππ(π¦, π) β π}
= π + π
And so (πΉ(π), . ) is a normed linear space.
Definition2.6.[3]Let π be any non-empty set and πΉ(π) be the set of all fuzzy sets on π. Then forπ, π β
πΉ π πππ π β πΎ the field of real numbers, define
π + π = π₯ + π¦, π π¬ π : π₯, π β π, π¦, π β π ππd
ππ = {(ππ₯, π) βΆ (π₯, π) β π}.
Definition2.7.[3]A two-fuzzy set on π is a fuzzy set on πΉ(π).
Definition2.8.[3]Let F(X) be a vector space over the real field K. A fuzzy subset N of
πΉ(π) Γ β,(β, the set of real numbers) is called a 2-fuzzy norm on πΉ(π) if and only if,
(N1) πΉππ πππ π‘ β β π€ππ‘π π‘ β€ 0, π(π, π‘) = 0
(N2) πΉππ πππ π‘ β β π€ππ‘π π‘ > 0, π(π, π‘) = 1 ππ πππ ππππ¦ ππ π = 0
(N3) πΉππ πππ π‘ β β, π€ππ‘π π‘ β₯ 0 , π(ππ, π‘) = π(π,
π¦
π
) ππ π β 0, π β πΎ (πππππ)
(N4) πΉππ πππ π , π‘ β β, π(π1 + π2, π , π‘) β₯ πππ{π(π1, π ), π(π2, π‘)}
(N5) π(π,β’) βΆ (0, β) β [0,1] is continuous
(N6) π(π, π‘)π‘ββ
πππ
= 1
Then the pair (πΉ(π), π) is a fuzzy two-normed vector space.
III. Mainresult
Definition 3.1.Let (πΉ(π), π,β) be a two-fuzzy normed space, then:
(a) A sequence{ππ } in πΉ(π) is said to fuzzy converges to π in πΉ(π) if for each π β (0, 1) and each
π‘ > 0, there exists π0 β π+
such that π (ππ β π, π‘) > 1 β π for all π β₯ π0 (Or
equivalently lim πββ π ππ β π, π‘ = 1 ).
(b) A sequence {ππ } in πΉ(π) is said to be fuzzy Cauchy if for each π β (0, 1) and each π‘ > 0, there
exists π0 β π+
such that π (ππ βππ, π‘) > 1 β π for all π, π β₯ π0 (Or equivalently
lim
π,πββ
π ππ β ππ , π‘ = 1).
(c) A two-fuzzy normed space in which every fuzzy Cauchy sequence is fuzzy convergent is said to be
complete.
Theorem 3.2. Let (πΉ(π), π,β) be a two-fuzzy normed space and let {ππ }, {π π} be two sequences in two-fuzzy
normed space πΉ(π), and for all πΌ1 β (0, 1) there exist πΌ β (0, 1) such that πΌ β πΌ β₯ πΌ1.
(1) Every fuzzy convergent sequence is fuzzy Cauchy sequence.
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(2) Every sequence in πΉ(π) has a unique fuzzy limit.
(3) If ππ β π then πππβ ππ, π β π½/ 0 .
(4) If ππ βπ, π πβπ, then ππ + π π β π + π.
Proof: (1) Let {ππ } be a sequence in πΉ(π) such that ππ β π then for all
π‘ > 0 , lim πββ π ππ β π,
π‘
2
= 1,
π ππ β ππ , π‘ = π (ππ β π) β (ππ β π), π‘ β₯ π ππ β π,
π‘
2
β π ππ β π,
π‘
2
, by taking limit:lim π,πββ π ππ β
ππ, π‘β₯lim πββ π ππβ π, π‘2βlim πββ π ππβ π, π‘2 =1β 1=1 but lim π, πββ π ππβ ππ, π‘β€1 then
lim π,πββ π ππ β ππ , π‘ =1 therefore {ππ } is a Cauchy sequence in πΉ(π).
(2) Let {ππ } be a sequence in πΉ(π) such that ππ β π and ππ β π as π β β and π β π then for all π‘ > π > 0 ,
lim πββ π ππ β π, π = 1, lim πββ π ππ β π, π‘ β π = 1 π π β π, π‘ β₯ π ππ β π, π β π ππ β π, π‘ β π
Taking limit as π β β:
π π β π, π‘ β₯ 1 β 1 = 1.βΉ ππ’π‘π π β π, π‘ β€ 1 βΉ π π β π, π‘ = 1.
Then by axiom (ii) π β π = 0 βΉ π = π.
(3) Since ππ βπ then if for all π β (0, 1) and for all π‘ >0, there exists
π0 β π+
such that π (ππ β π, π‘) > 1 β π for all π β₯ π0put π‘ =
π‘1
π
.
π (π ππ β ππ, π‘1) = π (ππ β π,
π‘1
π
) = π (ππ β π, π‘) > 1 β π
Then π ππ β π π.
(4) For each π1β (0, 1)there existsΞ΅ β (0, 1) such that (1 β π) β (1 β π) β₯ (1 β π1) .Since
π₯ π βπ₯ then for each π β (0, 1) and each π‘ > 0, there exists π1 β π+
such that π (ππ β π,
π‘
2
) > 1 β π for all
π β₯ π1, since π πβπ then if for each β (0, 1) and each π‘ > 0, there exists π2 β π+
such that
π (π π β π,
π‘
2
) > 1 β π for all π β₯ π2.Take π0 = πππ {π1, π2}, and for each π‘ > 0, there exists π0 β π+
such
that
π ((ππ + π π ) β (π + π), π‘) = π ((ππ β π) + (π π β π), π‘) β₯
π (ππ β π,
π‘
2
) β π (π π β π,
π‘
2
) > (1 β π) β (1 β π) β₯ (1 β π1) for all π β₯ π0. Then ππ + π π β π + π.
Theorem 3.3.Let (πΉ(π), π,β), (πΉ(π), π,β) be a two-fuzzy normed spaces and let ππ β π, π πβπ, such that
{ππ } and {π π} are two sequences in πΉ(π) and πΌ, π½ β π½ / {0} then πΌα΄ͺ (ππ )+π½ β΅ (π π) β πΌ α΄ͺ(π) + π½ β΅(π)
whenever α΄ͺ and β΅ are two identity fuzzy functions.
Proof: For all Ξ΅ β (0, 1) there exist π1β (0, 1) such that (1 β π1) β (1 β π1) β₯(1 β π), since
ππ β π, then for all π1 β (0, 1) and π‘ >0 there exists π1βπ+
such that
π (ππ β π,
π‘
2 πΌ
) > (1 β π1) for all π β₯ π1, and since π πβπ then for all π1 β (0, 1) and t >0 there exists
π2 β π+
such that π (π π β π,
π‘
2 π½
) > 1 β π1 for all π β₯ π2. Take π0 = πππ {π1, π2}, π β₯ π0
π ((πΌ α΄ͺ(ππ ) +π½β΅ (π π)) β (πΌ α΄ͺ(π) + π½ β΅(π)), π‘)= π πΌβΊ α΄ͺ ππ β α΄ͺ π + π½ β΅ π π β β΅ π , π‘ β₯
π (α΄ͺ(ππ )βα΄ͺ(π),
π‘
2 πΌ
)β π (β΅(π π) ββ΅(π),
π‘
2 π½
)
=π (ππ β π,
π‘
2 πΌ
) β π (π π β π,
π‘
2 π½
)> 1 β π1 β 1 β π1 β₯ (1 β π)
πΌ α΄ͺ (ππ) +π½β΅ (π π) β πΌ α΄ͺ(π) + π½ β΅(π).
Theorem 3.4.A two-fuzzy normed space (πΉ(π), π,β) is complete two-fuzzynormed space if every fuzzy
Cauchy sequence {ππ } in πΉ(π) has a fuzzy convergent subsequence.
Proof: Let {ππ } be a fuzzy Cauchy sequence in πΉ(π) and {πππ } be a subsequence of {ππ } such that πππ βπ,
π β πΉ(π).
Now to prove ππ βπ. For all π β (0, 1) there exist π1β (0, 1) such that (1 β π1) β (1 β π1) β₯(1 β π). Since
{ππ } is a fuzzy Cauchy sequence then for all π‘ >0 and π1β (0, 1) there exists π0 β π+
such that: π (ππ β ππ ,
π‘
2
)>
1 β π1, for all π, π β₯ π0.
Since {πππ } is fuzzy convergent to π, there exists ππ β₯ π0 such that π (πππ β π,
π‘
2
) > 1 β π1
π (ππ β π, t) =π ((ππ β πππ ) + (πππ β π₯),
π‘
2
+
π‘
2
) β₯
π (π₯ π βπ₯ππ ,
π‘
2
)β π (πππ β π,
π‘
2
) > 1 β π1 β 1 β π1 β₯ (1 β π).
Therefore ππ βπ, {ππ } is fuzzy convergent to π Hence (πΉ(π), π,β) is complete two-fuzzy normed space.
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Definition 3.5. Let πΉ(π), π,β and (πΉ(π), π,β) be two-fuzzy normed spaces. The function α΄ͺ: πΉ(π) β πΉ(π) is
said to be fuzzy continuous at π0 β πΉ(π)if for all π β (0, 1) and all π‘ > 0 there exist πΏ β (0, 1) and π > 0 such
that for all π β πΉ(π)
π (π β π0, π ) > 1 β πΏ implies π (α΄ͺ π β α΄ͺ(π0),π‘)> 1 β π.
The function π is called a fuzzy continuous function if it is fuzzy continuous at every point of πΉ(π).
Theorem 3.6. Every identity fuzzy function is fuzzy continuous function in two-fuzzy normed space.
Proof: For all π β (0, 1) and π‘ > 0 there exist π = π‘ and < π, πΏ β (0, 1) , π (ππ β π, π ) > 1 β πΏ
π (α΄ͺ(ππ )βα΄ͺ(π), π‘) = π (ππ β π, π ) > 1 β πΏ > 1 β π therefore α΄ͺ is a fuzzy continuous at π, since π is an
arbitrary point then α΄ͺ is a fuzzy continuous function.
Theorem 3.7.Let πΉ(π) be a two-fuzzy normed space over π½. Then the functions α΄ͺ: πΉ(π) Γ πΉ(π) β
πΉ(π),α΄ͺ(π, π) = π + π and
β΅: π½ Γ πΉ(π) β πΉ(π), β΅(π, π) = π π are fuzzy continuous functions.
Proof: (1) Let Ξ΅ β (0, 1) then there exists π1 β (0, 1) such that (1 β π1) β( 1 β π1) β₯ (1 βΞ΅).
let π, π β πΉ(π) and {ππ }, {π π} in πΉ(π) such that ππ β π and π πβ π as π β β, then for each π1 β (0, 1) and
each
π‘
2
> 0 there exists π1 β π+
such that π (ππ β π,
π‘
2
) > 1 β π1 for all π β₯ π1 , and for each π1 > 0 and
π‘
2
> 0 there exists π2 β π+
such that π π π β π,
π‘
2
> 1 β π1for all π β₯ π2 , put
π0 = πππ{π1, π2}π (π(π₯ π , π¦π ) β π(π₯, π¦), π‘) = π ((ππ + π π ) β (π + π), π‘) = π ((ππ β π) + ( π π β π), π‘) β₯
π ππ β π,
π‘
2
β π π π β π,
π‘
2
> (1 β π1) β ( 1 β π1) β₯ 1 β π for all π β₯ π0, therefore α΄ͺ(ππ , π π ) β
α΄ͺ(π, π) ππ π β β, α΄ͺ is fuzzy continuous function at (π₯, π¦) πππ (π₯, π¦) is any point in πΉ(π) Γ πΉ(π), hence α΄ͺ is
fuzzy continuous function.
(2) Let π β πΉ(π), πβ π½ and {ππ } in πΉ(π), {π π } in π½ such that ππ βπ and π π β π as π β β, then for each
π‘
2 π π
> 0, lim πββ π ππ β π,
π‘
2 π π
=1, |π π β π |β0 as π β β,
π (β΅(π π , ππ ) β β΅ (π, π), π‘) = π (π π ππ β ππ, π‘) = π ((π π ππ β π π π) + ( π π π β
π π), π‘) β₯ π (π π (ππ β π),
π‘
2
) β π (π (π π β π),
π‘
2
) = π ππ β π,
π‘
2 π π
β π (π,
π‘
2 π π βπ
) , by taking limit:
lim πββ π (β΅(π π , ππ ) β β΅ (π, π), π‘) β₯ lim πββ π ππ β π,
π‘
2 π π
β lim πββ π π,
π‘
2 π π βπ
=1 β 1 = 1 but
lim πββ π (β΅(π π , ππ ) β β΅ (π, π), π‘) β€ 1 then lim πββ π (β΅(π π , ππ ) β β΅ (π, π), π‘) = 1 then
β΅(π π , ππ ) β β΅(π, π) ππ π β β, β΅ is fuzzy continuous at (π, β΅) and (π, π) is any point in π½ Γ πΉ(π), hence β΅ is
fuzzy continuous.
Theorem 3.8. Let πΉ(π), π,β and (πΉ(π), π,β)be two-fuzzy normed spaces and let α΄ͺ βΆ πΉ(π) β πΉ(π) be a linear
function. Then α΄ͺ is a fuzzy continuous either at every point of πΉ(π) or at no point of πΉ(π).
Proof: Let π1and π2 be any two points of πΉ(π) and suppose α΄ͺ is fuzzy continuous at π1.Then for each π β (0, 1),
π‘ > 0 there exist πΏ β (0, 1)such that π β πΉ(π), π(π β π1, π ) > 1 β πΏ βΉ π (α΄ͺ(π) β α΄ͺ(π1), π‘) > 1 β πNow:
π π β π2, π > 1 β πΏ , π ((π + π1 β π2)βπ1, π ) > 1 β πΏ βΉ π (α΄ͺ(π + π1 β π2)βα΄ͺ(π1), π‘) > 1 β π βΉ
π (α΄ͺ π + α΄ͺ(π1) β α΄ͺ(π2) β α΄ͺ(π1), π‘) > 1 β π βΉ π (α΄ͺ π β α΄ͺ(π2), π‘) > 1 β π , α΄ͺ is a fuzzy continuous at π1,
since π2is arbitrary point. Hence α΄ͺ is a fuzzy continuous.
Corollary 3.9.Let πΉ(π), π,β and (πΉ(π), π,β) be two-fuzzy normed spaces and let α΄ͺ βΆ πΉ(π) β πΉ(π) be a
linear function. If α΄ͺ is fuzzy continuous at 0 then it is fuzzy continuous at every point.
Proof: Let {ππ } be a sequence in πΉ(π)such that there exist π0, andππ β π0, since α΄ͺ is fuzzy continuous at 0 then:
For all π β 0, 1 , π‘ > 0 there exist πΏ β 0, 1 , π > 0: ππ β π0 β πΉ π
, π ((ππ β π0)β0, π ) > 1 β πΏ β π (α΄ͺ(ππ β π0)β α΄ͺ(0), π‘) > 1 β π,
π (ππ β π0, π ) > 1 β πΏ β π (α΄ͺ(ππ ) β α΄ͺ(π0) βα΄ͺ(0), π‘) > 1 β π
π (ππ β π0, π ) > 1 β πΏ β π (α΄ͺ ππ β α΄ͺ(π0) β0, π‘) > 1 β π
π (ππ β π0, π ) > 1 β πΏ β π (α΄ͺ ππ β α΄ͺ(π0) , π‘) > 1 β π
ππ β π0 β α΄ͺ(ππ )β α΄ͺ(π0) therefore α΄ͺ is fuzzy continuous at π0 since π0 is arbitrary point, then α΄ͺ is fuzzy
continuous function.
Theorem 3.10.Let πΉ(π), π,β , (πΉ(π), π,β) be a two-fuzzy normed spaces, then the function α΄ͺ βΆ πΉ(π) β πΉ(π)
is fuzzy continuous at π0 β πΉ(π)if and only if for all fuzzy sequence {ππ } fuzzy convergent to π0 in π then the
sequence {α΄ͺ(ππ )} is fuzzy convergent to α΄ͺ(π0) in π.
Proof: Suppose the function α΄ͺ is fuzzy continuous in π0 and let {ππ } is a sequence in πΉ(π)such that ππ β π0.
Let π β 0, 1 , π‘ > 0, since α΄ͺ is fuzzy continuous inπ0 βΉ there exist πΏ β 0, 1 , π > 0, such that for all
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π β πΉ(π): π (π β π0, π ) > 1 β πΏ βΉ π (α΄ͺ(π) β α΄ͺ(π0), π‘) > 1 β π
Since ππ β π0, πΏ β 0,1 , π > 0 , there exist π β π+
such that
π (ππ β π0, π ) > 1 β πΏ for all π β₯ π hence π (α΄ͺ(ππ ) β α΄ͺ(π0), π‘) > 1 β π for all π β₯ π therefore α΄ͺ(ππ ) β α΄ͺ(π0).
Conversely suppose the condition in the theorem is true.
Suppose α΄ͺ is not fuzzy continuous at π0.
There exist π β 0, 1 , π‘ > 0 such that for all πΏ β 0, 1 , π > 0 there exist π β πΉ(π) and π (π β π0, π ) > 1 β
πΏ βΉ π (α΄ͺ(π) β α΄ͺ(π0) π‘) β€ 1 β π βΉ for all π β π+
there exist ππ β πΉ(π)such that
π (ππ β π0, π ) > 1 β
1
π
βΉ π (α΄ͺ(ππ ) β α΄ͺ(π0), π‘) β€ 1 β π that is mean ππ β π0in πΉ(π), but α΄ͺ(ππ ) β α΄ͺ(π0) in π
this contradiction , α΄ͺ is fuzzy continuous at π0.
Theorem3.11. Let (πΉ(π), π1,β) (πΉ(π), π2,β) be two-fuzzy normed spaces. If the functions α΄ͺ βΆ πΉ(π) β πΉ(π),
β΅: (π) β πΉ(π) are two fuzzy continuous functions and with for all π there exist π1 such that π1 β π1 β₯
π πππ π, π1 β 0, 1 then:
1 π + π, (2)ππ π€ π πππ π β π½/{0}, are also fuzzy continuous functions over the same filed π½.
Proof: (1)Let Ξ΅ β (0, 1) then there exists π1 β (0, 1) such that (1 β π1) β( 1 β π1) β₯ (1 βΞ΅).
Let {ππ } be a sequence in πΉ(π) such that ππ β π. Since α΄ͺ, β΅ are two fuzzy continuous functions at π thus for all
π1 β (0, 1) and all π‘ > 0 there exist πΏ β (0, 1) and π > 0 such that for all π β πΉ(π): π1(ππ β π, π ) > 1 β πΏ
implies π2 (α΄ͺ ππ β α΄ͺ(π),
π‘
2
)> 1 β π1.
And π1(ππ β π, π ) > 1 β πΏ implies π2 (β΅ ππ β β΅(π),
π‘
2
)> 1 β π1
Now: π2 α΄ͺ + β΅ ππ β α΄ͺ + β΅ π , π‘ = π2 α΄ͺ ππ + β΅ ππ β α΄ͺ π β β΅ π , π‘ β₯ π2 α΄ͺ ππ β α΄ͺ π ,
π‘
2
β
π2 β΅ ππ β β΅ π ,
π‘
2
> (1 β π1) β ( 1 β π1) β₯ (1 β π)
Then α΄ͺ + β΅ is fuzzy continuous function.
(2) Let {ππ } be a sequence in πΉ(π) such that ππ β π.Thus for all π1 β (0, 1) and for all π‘ > 0, there exist πΏ β
(0, 1) andπ > 0 β π1(ππ β π, π ) > 1 β πΏimplies π2 (α΄ͺ ππ β α΄ͺ(π), π‘) > 1 β π1 , take π‘1 = π‘ π .
Then for all π1 β (0, 1) and for all π‘1 > 0, there exist πΏ β (0, 1) and π > 0 β π1(ππ β π, π ) > 1 β πΏimplies
N2((π α΄ͺ) ππ β (πα΄ͺ)(π), π‘1) = π2(π( α΄ͺ(ππ ) β α΄ͺ(π)), π‘1)
= π2(α΄ͺ(ππ ) β α΄ͺ(π), π‘) > 1 β π1
Thenπα΄ͺis a fuzzy continuous function.
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