Abstract
In this paper, we extend prominent fixed-point theorems within the framework of symmetry, a structure increasingly relevant in decision-making, optimization, and uncertainty modeling. While previous studies have explored fixed-point theorems in non-Archimedean spaces, the influence of symmetry on the properties of mappings remains underexamined. To address this gap, we introduce and analyze the concepts of -contractions and -weak contractions, demonstrating how symmetry impacts the conditions for the existence of fixed points. Our methodology integrates these concepts in generalized neutrosophic metric spaces, providing a novel perspective on fixed-point theory. We perform a rigorous analysis, revealing new insights into their practical applications. However, our proposed system may face limitations in complex or dynamic environments, where additional conditions may be necessary to ensure the existence or uniqueness of fixed points.
Keywords:
fixed point; non-Archimedean; symmetric; weak contractive mapping; neutrosophic metric space MSC:
47H10; 54H25
1. Introduction
In recent decades, the study of fuzzy sets has gained significant attention in various fields, laying the foundation for advanced mathematical theories and applications. Introduced by Zadeh in 1965 [1], fuzzy sets allow for the representation of uncertain or imprecise information, providing a framework for modeling vagueness in real-world phenomena. This concept laid the foundation for many advancements in fuzzy mathematics, including the work of Atanassov [2], who extended fuzzy sets to intuitionistic fuzzy sets, incorporating both membership and non-membership functions.
In 1975, Kramosil and Michalek [3] developed fuzzy metric spaces, further expanding the utility of fuzzy sets into metric spaces by applying fuzzy logic to distance measurement. This approach allowed for the characterization of uncertainty in distance, making it suitable for applications in fields such as image processing and machine learning. George and Veeramani [4] and Sun et al. [5] explored generalized fuzzy metric spaces and their key properties, broadening their applicability.
Park [6] further extended this concept by introducing intuitionistic fuzzy metric spaces, which combine Atanassov’s intuitionistic fuzzy sets with Kramosil’s fuzzy metric spaces, addressing more complex forms of uncertainty in analysis and decision-making. This work aligns with a broader interest in fixed-point theorems in fuzzy environments, exemplified by Jeyaraman et al. [7], who extended the results to intuitionistic generalized fuzzy cone metric spaces.
Neutrosophic theory, proposed by Smarandache [8], introduced neutrosophic probability, sets, and logic, further generalizing fuzzy set theory by independently addressing indeterminacy, truth, and falsity. Kirisci and Simsek [9] contributed by defining neutrosophic metric spaces, offering a framework for dealing with uncertainty, indeterminacy, and vagueness. Sowndrarajan et al. [10] demonstrated the utility of these spaces by deriving fixed-point results for contraction theorems in neutrosophic metric spaces.
Fixed-point theory continued to evolve with contributions like those by Farokhzad Rostami [11], who explored contractive mappings in non-Archimedean G-fuzzy metric spaces, and Johnsy and Jeyaraman [12], who investigated fixed-point theorems for -contractions in generalized neutrosophic metric spaces. Akram et al. [13] introduced new generalized neutrosophic metric spaces and provided fixed-point results, particularly in decision-making models involving multiple criteria.
Mihet [14] examined fuzzy -contractive mappings in non-Archimedean fuzzy metric spaces, while Al-Khaleel et al. [15] in 2023 established fixed-point results for cyclic contractive mappings of Kannan and Chatterjea types in generalized metric spaces. Gupta and Mani [16] and Wardowski [17] further contributed to the practical application of fuzzy metric spaces, focusing on the existence and uniqueness of fixed points in computational models.
Banach’s pioneering work on fixed-point theorems [18] remains a cornerstone for modern research, providing a unified framework for understanding convergence and stability across various metric and fuzzy environments. Despite these advancements, a notable gap remains in the exploration of symmetry in non-Archimedean generalized neutrosophic metric spaces (GNMSs). Symmetry ensures that the distance-like functions yield consistent results regardless of the order of elements, an essential property for maintaining consistency in fixed-point theory and contraction mappings.
This study addresses this gap by introducing -contractions and -weak contractions in non-Archimedean GNMSs. These generalizations capture the non-Archimedean structure through strictly increasing functions, with -weak contractions providing a less restrictive condition than -contractions. We develop new fixed-point theorems, emphasizing the role of symmetry in the convergence process. By incorporating a new class of auxiliary functions under the contractivity rule, we extend the results from non-Archimedean fuzzy metric spaces to GNMSs, contributing to the theoretical framework of fixed-point theory and creating new opportunities for applications in decision-making, optimization, and complex systems analysis.
2. Preliminaries
Before demonstrating our main results, we review some essential definitions and facts that are referenced later in this paper.
Definition 1
([3]). A binary operation, denoted by , qualifies as a continuous t-norm (CTN) if it meets the following criteria:
- 1.
- ⊗ adheres to both associativity and commutativity properties.
- 2.
- ⊗ needs to be continuous.
- 3.
- For every , it holds that .
- 4.
- For any , if and , then .
Definition 2
([6]). A binary operation, denoted by ⊕, is defined as follows: it maps the interval to the interval . A continuous t-conorm (CTCN) is specified by the following conditions:
- 1.
- ⊕ adheres to both associativity and commutativity properties.
- 2.
- ⊕ needs to be continuous.
- 3.
- For every , it holds that .
- 4.
- For any , if and , then .
Definition 3.
A generalized neutrosophic metric space is described as a 6-tuple , where is a nonempty set, ⊗ represents a CTN, ⊕ represents a CTCN, and are fuzzy sets defined on . These elements satisfy the required conditions for all .
- (i)
- for all with ,
- (ii)
- ,
- (iii)
- for all with ,
- (iv)
- , then ,
- (v)
- , where is a permutation function,
- (vi)
- for all ,
- (vii)
- is continuous.
- (viii)
- ,
- (ix)
- for all with ,
- (x)
- , then ,
- (xi)
- , where is a permutation function,
- (xii)
- for all ,
- (xiii)
- is continuous.
- (xiv)
- ,
- (xv)
- for all with ,
- (xvi)
- , then ,
- (xvii)
- , where is a permutation function,
- (xviii)
- for all ,
- (xix)
- is continuous.
In the above definition, if the triangular inequalities (vi), (xii), and (xviii) for , and are replaced by
then the inequalities can also be equivalently expressed as:
The 6-tuple is called a non-Archimedean GNMS.
Example 1.
Let . Define the functions , , and as follows:
Use the parameters , , , and .
For ,
By substituting these values, we obtain
The values are as follows: , , and .
With these definitions, all functions remain bounded between 0 and 1. This ensures that satisfies the conditions for being a non-Archimedean GNMS.
Definition 4.
Let be a sequence in a GNMS . We say the following:
- (i)
- converges to ι if and only if , and ; i.e., for all and all , there exists such that and for all (in such a case, we will write .
- (ii)
- A sequence is considered a Cauchy sequence if and only if for every and , there exists an index such thatfor all and .Additionally, is a generalized Cauchy sequence if and only if for every and , there exists such thatfor all and .In other words,
- (iii)
- GNMS is considered complete if every Cauchy sequence in the space converges to a limit in that space.
Lemma 1.
Suppose that is a non-Archimedean GNMS. In that instance, is non-decreasing, and and are non-increasing, with reference to φ for all .
Proof.
Let be a non-Archimedean GNMS. From (1), for , ,
Consider two values and such that . By using the symmetry condition and the given inequality, for , we have
By setting , we obtain
Since by condition (iv) of Definition (3), and ⊗ is a t-norm, we conclude that
Thus, is non-decreasing with respect to .
Consider two values . From the given inequality, for , we have
By setting , we obtain
Since by conditions (x) and (xvi) of Definition (3) and ⊕ is a t-conorm, which preserves the inequality, we conclude
Thus, and are non-increasing with respect to . □
Lemma 2.
Let be a non-Archimedean GNMS. Then, , and are continuous functions on .
3. Fixed-Point Results Using Various -Contractive Mappings
In this section, we introduce and analyze symmetric -type contractions and weak contraction mappings, emphasizing fixed-point results in various mathematical contexts.
Definition 5.
A symmetric non-Archimedean GNMS is a non-Archimedean GNMS satisfying
for all with .
Remark 1.
A non-Archimedean GNMS is symmetric.
Definition 6.
Consider a strictly increasing continuous function . For any sequence of positive numbers , the condition that holds if and only if . Let Υ represent the set of all such functions χ.
Now, take the structure , which is a non-Archimedean GNMS. A mapping is termed a χ-contraction if there exists a constant such that
for all and , and, additionally, the following symmetric conditions hold:
Example 2.
The different types of mapping are as follows:
If , then each mapping accomplishing (2) is a χ-contraction such that for all and and in which and .
Note that, from χ and (2), it can be easily concluded that each χ-contraction Γ is a contractive mapping, that is,
for all , such that . Thus, each χ-contraction is continuous.
Numerical Example:
.
Define the mapping Γ as .
So, .
Assume that for different combinations of are as follows:
For :
For :
Using the mapping , we now verify that the mapping Γ satisfies the contractive inequalities.
Since , the condition holds.
Since , the condition holds.
Since , the condition holds.
Verification of :
Let :
Since , the inequality holds.
Since , the inequality holds.
This numerical example demonstrates that the mapping Γ is a χ-contraction and satisfies the required conditions for fuzzy sets , , and .
Theorem 1.
Let us consider as a non-Archimedean complete GNMS. Suppose that is a χ-contraction. Then, Γ has a unique fixed point in .
Proof.
Consider as an arbitrary fixed element. Define the sequence by the recurrence relation
If , then is a fixed point of , establishing the validity of the theorem. However, if for every , then, based on (2), we obtain
By iterating this method, we have
Let , Then, we have
By applying an identical method, we achieve
Now, we need to demonstrate that is a Cauchy sequence. According to this, let us assume that is not a Cauchy sequence. Then, there are and so that, for every , there exist with and
Suppose that is the smallest integer greater than that meets the condition in (8). Consequently, we obtain
for all , we obtain
Allowing , by (7), we obtain Also,
By assuming that and using (6), we have
From (8), we obtain
and by interpreting the limit as in (10) and from (6) and (9), we obtain
By using inequalities (2) with and ,
By taking the limit in (12) and applying (2), we obtain
which contradicts itself. Hence, is a Cauchy sequence in . It is clear that, in the completeness of , there exists such that .
Finally, the continuity of , and yields
Now, we can prove that has a unique fixed point. Pressume that and are two fixed points of . Certainly, if for , then we obtain
which are the contradictions. Thus, possesses a unique fixed point. Therefore, the theorem holds. □
Example 3.
Let and
for all . Let such that for all and define by for all . Clearly, is a complete non-Archimedean .
Case 1. We assume that . Since and . So, there exists a such that
We can easily prove that , and
Case 2. Let and . Since and , then . Hence, we have
So, there exists a such that , and
Case 3. Let and ; it is easy to see that , and Therefore, Γ is a χ-contraction. Then, all the conditions of Theorem (1) hold, and Γ has the unique fixed point .
Definition 7.
Consider as a non-Archimedean GNMS. A mapping is referred to as a χ-weak contraction if there exists a such that
for all and .
It is important that every -contraction qualifies as a -weak contraction. However, the reverse is not necessarily true.
Example 4.
Let , where .
and for all . Clearly, is a complete non-Archimedean . Let such that for all and define by Since Γ is not continuous, Γ is not a χ-contraction by (4). Now, we show that Γ is a χ-weak contraction for all .
Case 1. Let and
Verification of χ-contraction mappings:
Consider that for all . For , , . , . Since , the contraction holds true. Similarly, verification can be performed for and using the same approach. So, there exists a such that
Case 2. Let and ,
Verification of χ-contraction mappings:
Consider the function for all . For , when , . When , . Since , the contraction holds true.
Similarly, the verification can be performed for and using the same approach. So, there exists a such that
Case 3.
Let and ,
Verification of χ-contraction mappings:
Consider the function for all . For , when , . When , . Since , the contraction property holds.
Similarly, the verification can be performed for and using the same approach. So, there exists a such that
By proving the remaining cases, we find that Γ is a χ-weak contraction.
Theorem 2.
Consider a complete non-Archimedean GNMS represented as . If there exists a mapping that acts as a χ-weak contraction, then Γ is guaranteed to have exactly one fixed point within .
Proof.
Let an arbitrary fixed element be chosen. Construct the sequence such that for all . If at some point, then is the fixed point of , completing the proof. Otherwise, for every .
Thus, using Equation (14), we obtain the following result:
If there is some such that
it follows from (15) that
This leads to a contradiction, and, thus,
for every . Hence, based on (15), (17), and the properties of , we conclude that
for all . This means that
By taking , we obtain , , . Then, we have , , and .
Using similar reasoning as in the proof of Theorem (1), we conclude that the sequence is Cauchy. Given that is complete, there exists some such that . Next, we demonstrate that is a fixed point of . Since is continuous, two possible cases arise.
Case I. For every , there exists an index such that and , with . Consequently, we have
This confirms that is indeed a fixed point of .
Case II. There is a natural number such that for all , . That is, , and so for all . It follows from (14) that
Since , , and , if , and , then there is a natural number such that, for all , it follows that
From (18), we have
for all . Given that is continuous, taking the limit as yields
which is a contradiction.
Therefore, , , and ; thus, is a fixed point of . Next, we show that this fixed point is unique. Assume that and are two distinct fixed points of . If , then it follows that . According to (14), we obtain
which is a contradiction.
Then, , , and ; that is, . Thus, the fixed point of is uniquely determined. □
Example 5.
Let be a non-Archimedean , and let Γ be as considered in Example (4). Let be defined by
for all . Then, Γ is a χ-weak contraction.
Therefore, Theorem (2) is applicable to Γ, and the unique fixed point of Γ is .
Since , this confirms that is indeed the unique fixed point of Γ.
4. () Contractions on Non-Archimedean GNMS
In this section, we examine a broader class of auxiliary functions that generate various contractive conditions. We establish that the function , commonly found in fixed-point theorems in the neutrosophic context, can be substituted with more suitable and general functions.
Definition 8
([11]). Consider Φ as the set of all functions that fulfill the following criteria:
- (1)
- if and only if ;
- (2)
- ;
- (3)
- ϕ is continuous at .
Definition 9
([11]). Define Ψ as the set of functions that meet the following criteria:
- (1)
- ψ is non-decreasing;
- (2)
- ;
- (3)
- For any sequence converging to 0, the sequence also converges to 0, where denotes the n-th iterate of ψ.
Additionally, the functions in Ψ are continuous at .
Definition 10.
Let denote the set of functions that satisfy the following conditions:
- )
- For any sequence , if and only if ;
- )
- For any sequence , if and only if .
These conditions are satisfied, for example, by a strictly decreasing bijective function η mapping to such that both η and its inverse are continuous (at least at the endpoints of their corresponding domains). A specific example is the function for . However, the functions in do not necessarily need to be continuous or monotone.
Theorem 3.
Consider as a complete non-Archimedean GNMS, and consider as a mapping. Assume that there exist , , , and such that
for all and all for which , and . If there exists such that , then Γ has at least one fixed point. Furthermore, assume that, for any with , we have . Then, Γ admits a unique fixed point.
Proof.
Observe that the condition (19) indicates that if , then must be applicable to . Hence, , which signifies that
By setting , define sequence by for all . If there is a natural number such that , then is a fixed point of , completing the proof of existence.
Alternatively, suppose that for all . Given that , and , there is a such that , , and . Additionally, since , there exists a value (which we can assume to be at least ) such that .
Hence, , .
From (20), it follows that . Using mathematical induction, it can be shown that, for for all . If and , then . Given that and are non-decreasing functions, while and are non-increasing functions, it can be concluded that, if and , then
We claim that
For any , we need to demonstrate the following: Let be arbitrary. Since and are continuous at , it follows that . Therefore, for , there exists a natural number such that . Consider such that . Using the contractivity condition (19) with and , we obtain
in which we apply as stated in (21). By applying this reasoning repeatedly, we find that
where we use , , and by (21). Since is non-decreasing, then
By combining inequalities (23) and (24), we conclude that
Inequality (21) allows us to apply this argument n times, leading to the conclusion that
for all . As a consequence,
As the sequence , , and , we have . By (25), we deduce that , , and .
In particular, as , condition () implies that , . Because , is a non-decreasing function and are non-increasing functions with respect to , so we have
Considering (26), we note that , , and for all ; this implies that (22) is satisfied. According to Definition (4), is a generalized Cauchy sequence in . Since is generalized complete, there exists an element such that converges to . We now assert that is a fixed point of . To demonstrate this, for any and for every ,
By lemma (2),
Let us demonstrate that the first term in (27) converges to 1 as approaches infinity. Given that is continuous at , we have .
Since , there exists such that . Since .
So, , , and . Hence, there exists such that , , and for all . By applying the contractivity condition (19) to and for , we obtain
Therefore,
Taking into account that , , and , we deduce that
Taking the limit as in (27) and applying (28) and (29) yield
We have proven that , , and for all , and the axioms (iv), (x), and (xvi) of definition (1.1) guarantee that . In other words, is a fixed point of .
We now investigate the uniqueness of the fixed point of . Suppose that has two distinct fixed points, and . This leads to a contradiction, showing that and must be the same.
According to the assumption, , and . Then, there exists such that . Moreover, there exists such that . Consequently, as and are non-decreasing functions, are non-increasing functions with respect to ,
, ,
.
From (20), we have
, , and . By induction, , , for all . We claim that
To demonstrate this, consider an arbitrary and assume that such that .
Since , and given that and are non-decreasing functions while and are non-increasing functions with respect to , it follows that, if and , then
Using the contractivity condition (19) for and leads to the conclusion that
where we use by (31). By applying this reasoning repeatedly, we find that
where we use by (31).
Given that is non-decreasing, it follows that
By merging inequalities (32) and (33), we derive
Inequality (31) allows us to apply this argument n times, leading to the result that
for all . As a consequence,
As the sequence , and , we have .
By (34), we deduce that . In particular, as , Definition (10) implies that . This indicates that (30) is satisfied.
To proceed, we need to demonstrate that for every . Consider an arbitrary . Since and , there exists a natural number such that . Hence, , , and , so , and . By varying , we can infer that based on the definiton of a GNMS, which contradicts the assumption that . Therefore, must have exactly one fixed point. □
Example 6.
Let be a complete non-Archimedean GNMS, where
, the set of real numbers between 0 and 1. The neutrosophic metric functions , , and are defined as
for all and .
Let the mapping be defined as for all .
Now, choose , , and , with .
Verifying the Conditions:
1. Condition for :
Substituting the values:
Since maintains a bounded distance, the inequality holds.
2. Condition for :
Substituting the values:
This inequality holds because the difference flips the values of α but does not increase the overall distance.
3. Condition for :
Substituting the values:
This is satisfied for the same reason as above, where the flipping does not affect the distance significantly.
Existence of a Fixed Point:
For , we have
Thus, has a fixed point at .
Since satisfies all the conditions of the theorem, the fixed point at is unique.
5. Conclusions
In this study, we established several significant fixed-point theorems for self-mappings in non-Archimedean GNMSs, focusing on -contractions and -weak contractions. Our results demonstrate that the proposed class of contractive conditions for auxiliary functions effectively extends the existing framework. This advancement not only broadens the scope of our findings but also enhances their applicability in contexts where symmetry plays a crucial role in the behaviour of mappings. The results underscore the importance of symmetry in ensuring the existence and uniqueness of fixed points, providing a robust foundation for future applications in metric space theory. Furthermore, our findings show that the developed conditions can yield valuable insights across various mathematical domains, reinforcing their versatility. However, the applicability of these results is limited to symmetric settings, and both -contractions and -weak contractions must be strictly increasing functions; otherwise, the conditions may not hold. Looking ahead, future research could explore the applicability of these generalized results in more dynamic and complex systems, which would further enhance both their practical utility and theoretical significance. Additionally, investigating the role of symmetry in influencing the dynamics of fixed-point behaviour could offer deeper insights and contribute to advancements in mathematical theory and its applications.
Author Contributions
Investigation, J.A.J., M.J. and R.S.; methodology, J.A.J., M.J. and R.S.; supervision, R.S.; writing-original draft, J.A.J., M.J. and R.S.; writing-review and editing, M.J. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Data Availability Statement
Data are contained within the article.
Acknowledgments
The authors are indebted to the reviewers for their helpful suggestions, which have improved the quality of this paper. This work was supported by Directorate of Research and Innovation, Walter Sisulu University.
Conflicts of Interest
The authors declare no conflicts of interest.
Abbreviations
The following abbreviations are used in this manuscript:
| GNMS | Generalized Neutrosophic Netric Spaces |
| CTN | Continuous t-norm |
| CTCN | Continuous t-conorm |
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