Abstract
This paper aims to introduce the concept of rational type revised fuzzy-contraction mappings in revised fuzzy metric spaces. Fixed point results are proven under the rational type revised fuzzy-contraction conditions in revised fuzzy metric spaces with illustrative examples provided to support the results. A significant role will be played by this new concept in the theory of revised fuzzy fixed point results, and it can be generalized for different contractive type mappings in the context of revised fuzzy metric spaces. Additionally, an application of a nonlinear integral type equation is presented to obtain the existing result in a unique solution to support the work.
MSC:
46N20; 46S40; 47H10; 58C30
1. Introduction
In the year 2018, Alexander Sostak [1,2,3] introduced the idea of revised fuzzy metrics, which allow for the progressive evaluation of an elementβs inclusion in a collection. Revised fuzzy contraction mappings were described by Muraliraj and Thangathamizh [4,5,6,7], and the existence of fixed points was established for it. Cone Revised fuzzy metric space and revised fuzzy moduler meric space are also specified. Numerous general topology ideas and findings were subsequently applied to the revised fuzzy topological space.
It is well-known that GV-fuzzy metrics are non-decreasing in the third variable. From here, or independently, by analyzing the definition of an RGV-fuzzy metric, we conclude that RGV-fuzzy metrics are non-increasing in the third variable. This allows us to give the following visual interpretation of an RGV-fuzzy metric. Assume that we are looking from a distance at a plane filled up with pixels. We estimate the distance between pixels x and y by means of an RGV-fuzzy metric . Being close to the plane, we see quite clearly how far the two pixels x and y are. However, going further from the plane, our ability to distinguish the real distance between different pixels becomes weaker, and, at some moment, two different pixels can merge into one in our eye-pupil.
RGV-fuzzy metrics are equivalent to GV-fuzzy metrics; the theories based on these concepts are equivalent. The difference is in the definitions, the proofs, and the interpretations of results. In particular, in the case of revised fuzzy metrics, we have the natural interpretation of the standard situation: the longer the segments of two infinite words taken into consideration, the more precise the obtained information about the closeness of the two words.
The concept of an intuitionistic fuzzy metric on a set used two functions satisfying inequality for all , . The first one of these functions, , describes the degree of nearness, while describes the degree of non-nearness of points on the level . So, actually, in definition is an ordinary GV-fuzzy metric, and therefore, it is based on the use of a t-norm . On the other hand, function which in some sense complements function M, is based on a t-conorm (that is, probably, unrelated to the t-norm ). In contrast to the case of an intuitionistic fuzzy metric, we, when defining an RGV-fuzzy metric, started with a βclassicβ GV-metric and just reformulated the axioms from [3] by using involution. So, in our approach, a t-conorm β in the definition of a fuzzy metric is used to evaluate the degree of nearness of two points, and hence, it is opposite to the role of a t-conorm in the definition of an intuitionistic fuzzy metric.
The following articles [2,3,4,5,8,9,10,11,12,13,14,15,16,17,18,19,20,21] contain some triangular characteristic and integral type application findings in the theory of fixed point.
The aim of this research is to introduce the concept of rational type revised fuzzy-contraction mappings in G-complete RFM-spaces. This new theory is crucial in the study of revised fuzzy fixed point results and can be generalized for various contractive type mappings in the context of revised fuzzy metric spaces. Additionally, an integral type application is presented in the space, and a result is proved for a unique solution to support the work. The application section of the paper is of utmost importance as this concept can be utilized to present different types of nonlinear integral equations for the existence of unique solutions for their results.
2. Preliminaries
Definition 1 [1].
A binary operation of the form is said to be a t-conorm if it satisfies the following conditions:
- (a)
- is associative and commutative, continuous.
- (b)
- , ,
- (c)
- . Whenever, and . .
Example 1 [1].
- i.
- Lukasievicz t-conorm: ,
- ii.
- Product t-conorm:,
- iii.
- Minimum t-conorm:
Definition 2 [1].
Let be a set and is a continuous t-conorm. A Revised fuzzy metric or an (shortly, RFM), on the set is a pair or simply , where the mapping satisfying the following conditions, and ,
( 1)
( 2)
( 3)
( 4)
( 5) is right continuous. Then, is said to be a Revised fuzzy metric on .
Definition 3 [6].
Let the triple
be a RFM-space and . Then, known as a revised fuzzy contractive, if there is so that for all .
Definition 4 [8].
Let the triple be an RFM-space and the
is triangular if
and .
Definition 5 [6].
Let the triple be an RFM-space and . Then, known as a revised fuzzy contraction, if so that for all .
Lemma 1 [6].
Let the triple be an RFM-space and let a sequence in converge to a point , as , for .
Definition 6.
Consider a nonempty
and a mapping . Define a set
for every then is said to be generalized revised fuzzy metric (shortly, -RFM) and , it satisfies the following conditions:
( 1)
( 2)
( 3)
( 4) such that if then
( 5) is continuous and . Then, is said to be Generalized revised fuzzy metric space (shortly -RFMS).
Example 2.
Consider a generalized metric space . Define a mapping by and . Then, is Generalized fuzzy metric space (-RFMS), where the t-conorm is taken as product norm. i.e.,
Proposition 1.
Every revised fuzzy metric space
is a generalized revised fuzzy metric space (
-RFMS).
Definition 7.
Let
be a generalized revised fuzzy metric space (-RFMS). A sequence in is said to be -convergent sequence if , .
Definition 8.
Let be a generalized revised fuzzy metric space (-RFMS). A sequence in is said to be -Cauchy sequence if for all .
Definition 9.
A generalized revised fuzzy metric space in which every
-Cauchy sequence is
-convergent is called a
-complete generalized revised fuzzy metric space (shortly,
-complete RFM-space).
3. Main Results
In this section, we define rational type revised fuzzy-contraction maps and prove some unique fixed-point theorems under the rational type revised fuzzy-contraction mappings in -complete RFM-spaces.
Definition 10.
Let the triple
be an RFM-space; a mapping
is said to be a rational type revised fuzzy-contraction if
, such that
.
Theorem 1.
Let the triple
be a -complete RFM-space in which is triangular and a mapping is said to be a rational type revised fuzzy-contraction satisfying (5) with . Then, has a fixed point in .
Proof.
Let and , . Then, by (5), for ,
and after being simplified,
Now, by inference, for , we have that from (7) and (8).
Consequently, Revised fuzzy contractive sequence in is represented by , then,
We now demonstrate that is a -Cauchy sequence, assuming that and that there exists a fixed , such that
Thus, it is established that the sequence is a -Cauchy. Given that is -complete, for all , as ,
Since is triangular, we can derive from (5), (10), and (12),
Thus, it is established that . β‘
Corollary 1.
(Revised fuzzy Banach contraction principle).
Let be a -complete RFM-space in which is triangular and a mapping is a revised fuzzy-contraction satisfying (4) with . Then, has a unique fixed point in .
Example 3.
Let
,
be a continuous t-conorm, and
be defined as
The one can easily verify that
is triangular and
is a
-complete RFM space. Now we define a mapping
as
Then, we have
Hence, a mapping
is a revised fuzzy contraction. Now, from Example 1 (iii), for
,
Hence, all the conditions of Theorem 1 are satisfied with .
A mapping has a fixed point. i.e., .
Now, we prove a generalized rational type revised fuzzy contraction theorem.
Theorem 2.
Let
is a
-complete RFM-space. Which
is triangular and a mapping
satisfies
with . Then, has a unique fixed point.
Proof.
Let and , . Then, by (19), for ,
By the Example 1 (iii), , and after simplification, we have
Similarly, for , we have
Now, from (21) and (22) by induction, for , we have that
As . Then, is revised fuzzy contractive sequence in ; therefore,
Now, to prove that is a -Cauchy sequence, let and there is a fixed , such that
Hence, it is shows that is a -Cauchy sequence. Since is -complete, , , as ,
Since is triangular,
Now, from (19), (24) and (26), for , we have
By the Example 1 (iii), , and after simplification, we have
Then,
Now, from (26), (27), and (30), as we get that
and where , and hence , i.e., , for .
Uniqueness. Let such that and . Then, from (19) and Example 1 (iii), for , we have
Hence, , and this implies that , for . β‘
Corollary 2.
Let
is a
-complete RFM-space in which
is triangular and a mapping
satisfies
with . Then, has a unique fixed point.
Corollary 3.
Let
is a
-complete RFM-space in which
is triangular and a mapping
satisfies
with
. Then,
has a unique fixed point.
Corollary 4.
Let
is a
-complete RFM-space in which
is triangular and a mapping
satisfies
for all with . Then, has a unique fixed point.
Example 4.
By the Example 3, Define
as
Then, we have
A mapping
is a revised fuzzy contraction. Now, by the Example 1 (iii), for
,
and after simplification, we get the following result
Its shows, all the conditions of Theorem 2 are satisfied with , and , and has a fixed point, i.e., .
4. Application
In this section, we present an integral type application to support our work. Let be the space of all R-valued continuous functions on the interval , where . The nonlinear integral equation is
where and . The induced metric can be defined as
The operation is defined by , . A standard revised fuzzy metric can be defined as
Hence, one can easily verify that is triangular and is a -complete RFM-space.
Theorem 3.
Let the integral equation be defined in (40), and such that
satisfies
where
So, is the only place where the integral problem in (40) can be solved.
Proof.
Define the integral operator by
is clearly specified, and (40) has a singular answer only if has a singular fixed point in . We must now demonstrate that the integral operator is covered by Theorem 1. Then, , we have the subsequent two cases:
- (a)
- If then, from (42) and (43), we have (44),
- , inequality (47) is true. With and , the integral operator thus meets all the requirements of Theorem 1 (5). The answer to (40) exists in , making it the only fixed point for the integral operator .
- (b)
- If then, from (42) and (43), we have (44),
Here, we condense the expression , and by applying Example 1 (iii) and (42) we obtain for ,
Now that we have (49) and (51)
Now, . Inequality (52) holds if . Thus, the integral operator satisfies all the conditions of Theorem 1 with and in (5). The integral operator has a unique fixed point; i.e., Equation (40) has a solution in . β‘
5. Conclusions
The concept of rational type revised fuzzy-contraction maps in RFM-spaces is presented in this paper, and some rational type fixed point theorems are proved in -complete RFM-spaces under the rational type revised fuzzy-contraction conditions, utilizing the βtriangular property of revised fuzzy metric.β In the final section, an integral type application for rational type revised fuzzy-contraction maps is presented, and a result of a unique solution for an integral operator in RFM-space is proved. In this direction, more rational type revised fuzzy-contraction results in -complete-spaces with various types of applications can be demonstrated.
Author Contributions
All the authors contributed equally in conceptualization, methodology, formal analysis, and writing. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
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