Abstract
In this paper, we consider a resolvent operator which depends on the composition of two mappings with ⊕ operation. We prove some of the properties of the resolvent operator, that is, that it is single-valued as well as Lipschitz-type-continuous. An existence and convergence result is proven for a generalized implicit set-valued variational inclusion problem with ⊕ operation. Some special cases of a generalized implicit set-valued variational inclusion problem with ⊕ operation are discussed. An example is constructed to illustrate some of the concepts used in this paper.
MSC:
47H09; 49J40
1. Introduction
Because of applications in optimization problems, mathematical programming, equilibrium problems, engineering, economics and operation research etc., suitable progress has been achieved in both theory and application of various types of variational inequalities (inclusions) and their generalizations. After careful observation, it was noticed that the projection method and its variant forms cannot be applied for solving variational inclusions. This fact motivated researchers to use techniques based on resolvent operators. The resolvent operator and its variant forms represent an important tool for finding the approximate solutions of variational inclusions. The main idea in this technique is to establish the equivalence between the variational inclusions and the fixed point problems using the concept of resolvent. For more details, we refer to [,,,,,,,,,,,,,,,,,,,] and the references therein.
⊕ operation, that is, XOR-operation is a binary operation and behaves like the ADD operation: It takes two arguments and produces one result. This operation is commutative, associative, and self-inverse. In Boolean algebra, it is the same as addition modulo(2). XOR represents the inequality function, i.e., the output is true if the inputs are not alike; otherwise, the output is false. It is interesting to note that if we take the XOR of any number with 1, then we get the complement of the number, and if we take XOR with 0, then we get the same number. XOR terminology is used to generate pseudo-random numbers, to detect error in digital communication, inside CPU it helps in addition operation, etc.
Li and his co-authors [,,] first used the ⊕ operation for solving some classes of variational inclusions and after that, Ahmad and his co-authors [,,] also solved some generalized variational inclusions with ⊕ operation.
In this paper, we consider a resolvent operator with ⊕ operation involving composition of two mappings. We proved some properties of the resolvent operator. An iterative algorithm was constructed to solved a generalized implicit set-valued variational inclusion problem with ⊕ operation in real ordered positive Hilbert spaces. An existence and convergence result was proven for a generalized implicit set-valued inclusion problem with ⊕ operation. Some special cases are discussed and an example is given in support of some of the concepts used in this work.
2. Preliminaries
Let C be a cone with partial ordering “≤”. An ordered Hilbert space with norm and inner product is called positive if and then holds. Throughout the paper, is assumed to be a real ordered positive Hilbert space. We denote (respectively, ) as the family of nonempty (respectively, compact) subsets of and d is the metric induced by the norm and is the Hausdörff metric on
Now, we illustrate some known concepts and results which are needed to prove the main result. The following concepts and results can be found in [,,,,,,,].
Definition 1.
A nonempty closed convex subset C of is said to be a cone if:
- (i)
- for any and any ;
- (ii)
- if and then .
Definition 2.
Let C be the cone, then:
- (i)
- C is called a normal cone if there exists a constant such that implies , for all ;
- (ii)
- for any if and only if
- (iii)
- x and y are said to be comparative to each other if either or holds and is denoted by
Definition 3.
For any denotes the least upper bound and denotes the greatest lower bound of the set Suppose and exist, then some binary operations are given below:
- (i)
- (ii)
- (iii)
- (iv)
The operations ⊕, and ⊙ are called OR, AND, XOR, and XNOR operations, respectively.
Lemma 1.
If then lub{} and glb{} exist such that and
Lemma 2.
For any natural number and as then
Proposition 1.
Let ⊕ be an XOR operation and ⊙ be an XNOR operation. Then the following relations hold for all and :
- (i)
- (ii)
- if then
- (iii)
- (iv)
- if
- (v)
- if then if and only if
- (vi)
- (vii)
- (viii)
- if and w are comparative to each other, then
- (ix)
- if .
Proposition 2.
Let C be a normal cone in with constant then for each the following relations hold:
- (i)
- (ii)
- (iii)
- (iv)
- if then
Definition 4.
Let be a single-valued mapping, then:
- (i)
- F is said to be comparison mapping, if for each then and
- (ii)
- F is said to be strongly comparison mapping, if F is a comparison mapping and if and only if for all
Definition 5.
A single-valued mapping is said to be β-ordered compression mapping if F is a comparison mapping and:
Definition 6.
Let be a set-valued mapping. Then:
- (i)
- M is said to be a comparison mapping if for any and if then for and
- (ii)
- A comparison mapping M is said to be α-non-ordinary difference mapping if:
- (iii)
- A comparison mapping M is said to be θ-ordered rectangular if there exists a constant such that:
Definition 7.
A set-valued mapping is said to be λ-XOR-ordered strongly monotone compression mapping if then there exists a constant such that:
Definition 8.
A set-valued mapping is said to be -Lipschitz continuous if for all , there exists a constant such that:
Definition 9.
A single-valued mapping is said to be Lipschitz-type-continuous if there exists a constant such that:
Let be the single-valued mappings, we consider the composition of H and F as:
Definition 10.
Let be the single-valued mappings such that is strongly comparison and β-ordered compression mapping. Then, a set-valued comparison mapping is said to be -XOR-NODSM if M is an α-non-ordinary difference mapping and λ-XOR-ordered strongly monotone compression mapping and for
Definition 11.
Let be the single-valued mapping such that is strongly comparison and β-ordered compression mapping. Suppose that the set-valued mapping is -XOR-NODSM mapping. We define the resolvent operator by:
Now, we present some properties of the resolvent operator defined by (1).
Proposition 3.
Let be the single-valued mappings such that is β-ordered compression mapping and is the set-valued θ-ordered rectangular mapping with . Then, the resolvent operator is single-valued.
Proof.
For any given and let Then:
and:
Using (i) and (ii) of Proposition 1, we obtain:
Thus, we have:
Since M is -ordered rectangular mapping, is -ordered compression mapping and using (2), we have:
i.e.,
which shows that:
Therefore i.e., the resolvent operator is single-valued, for . □
Proposition 4.
Let be -XOR-NODSM set-valued mapping with respect to Let be the single-valued mappings such that is strongly comparison mapping with respect to Then the resolvent operator is a comparison mapping.
Proof.
Since M is -XOR-NODSM set-valued mapping with respect to i.e., M is -non-ordinary difference as well as -XOR-ordered strongly monotone compression mapping with respect to For any let and:
and:
Since M is -XOR-ordered strongly monotone compression mapping and using (3) and (4), we have:
which implies either:
Thus, in both cases, we have:
Since is strongly comparison mapping with respect to thus, we have i.e., the resolvent operator is a comparison mapping. □
Proposition 5.
If all the mappings and conditions are the same as those stated in Proposition 3, then the following condition holds:
i.e., the resolvent operator is Lipschitz-type-continuous mapping.
Proof.
Let and:
and:
Using (iii) of Proposition 2, we have:
It follows that:
This completes the proof.
In support of Proposition 3–5, we have the following example. □
Example 1.
Let with the usual inner product and norm, and let be a normal cone in . Let and be the mappings defined by:
Let then we calculate:
i.e.,
Hence, is -ordered compression mapping.
Suppose that is a the set-valued mapping defined by:
It can be easily verified that M is a comparison mapping, 1-XOR-ordered strongly monotone comparison mapping, and 1-non-ordinary difference mapping.
Let and then we evaluate:
i.e.,
Thus, M is a -ordered rectangular comparison mapping. Further, it is clear that for . Hence, M is an -XOR-NODSM set-valued mapping.
The resolvent operator defined by (1) is given by:
It is easy to check that the resolvent operator defined above is a comparison and single-valued mapping.
Further:
i.e.,
That is, the resolvent operator is -Lipschitz-type-continuous.
3. Formulation of The Problem and Existence of Solution
Let be a real positive Hilbert space. Let and be the set-valued mappings and let be a single-valued mapping. Then, we consider the following problem:
Find , , and such that:
We call the problem in Equation (9) a generalized implicit set-valued variational inclusion problem with ⊕ operation.
It is clear that for suitable choices of operators involved in the formulation of problem (9), one can obtain many related problems.
The following Lemma is a fixed point formulation of the problem in Equation (9).
Lemma 3.
The generalized implicit set-valued variational inclusion problem involving ⊕ operation (9) has a solution , , , if and only if it satisfies the following equation:
where is a constant.
Proof.
Using the definition of the resolvent operator , and Equation (10), we get:
which implies that , the required generalized implicit set-valued variational inclusion problem with ⊕ operation (9).
Conversely, suppose that generalized implicit set-valued variational inclusion problem with ⊕ operation (9) is satisfied, that is, , , and such that:
which shows that:
Thus, Equation (10) is satisfied. □
Based on Lemma 3, we establish the following iterative algorithm to obtain the solution of the problem in Equation (9).
Iterative Algorithm 1.
For any given , choose , , and using (10), let:
Since , , , by the Nadler’s theorem [], there exists , , , and using Proposition 2, we have:
where is the Hausdorff metric on . Let:
Again by Nadler’s theorem [], there exist , , such that:
Continuing the above procedure inductively, we have the following scheme:
Since , , , such that:
where .
Theorem 1.
Let be a normal cone with constant and be the single-valued mappings such that be strongly comparison, β-ordered compression mapping, G is -ordered compression mapping in the first argument, -ordered compression mapping in the second argument, and -ordered compression mapping in the third argument. Let be the set-valued mappings such that A is --Lipschitz-continuous, B is --Lipschitz-continuous, and C is --Lipschitz-continuous. Suppose that is - XOR-NODSM set-valued mapping with respect to and θ-ordered rectangular mapping with . If , and the following condition is satisfied:
where and ; all are positive constants.Then, the generalized implicit set-valued variational inclusion problem with ⊕ operation (9) has a solution . Moreover, the iterative sequences generated by Algorithm 1 converge strongly to , the solution of generalized implicit set-valued variational inclusions problem with ⊕ operation (9).
Proof.
By Algorithm 1 and Proposition 1, we have:
Using Proposition 2 and Lipschitz-type-continuity of the resolvent operators (1) and (12), we have:
where .
Since G is -compression mapping in the first argument, -compression mapping in the second argument, and -compression mapping in third argument, A is --Lipschitz-continuous, B is --Lipschitz-continuous, and C is --Lipschitz-continuous, using Algorithm 1, we have:
As is -ordered compression mapping, we have:
As , we have:
where
Let
We know that as . It follows from condition (11) that , and consequently, is a cauchy sequence in and since is complete, there exists an such that , as . From Algorithm 1, we have:
It is clear from Euqations (17)–(19) that , , and are also cauchy sequences in . Let , and , as . In view of Lemma 3, we conclude that such that , , and is a solution of a generalized implicit set-valued variational inclusion problem with ⊕ operation (9). Now, we show that with , we have:
which implies that , and since , it follows that . Similarly, we can show that and , respectively. This complete the proof. □
4. Conclusions
In this paper, we considered a generalized implicit set-valued variational inclusion problem with ⊕ operation, which includes many previously studied problems in ordered spaces as special cases. A resolvent operator which involves composition of two mappings was considered, and we proved some properties of it. An existence and convergence result was proven for our problem in real ordered positive Hilbert spaces.
We remark that our results may be generalized further in higher dimensional spaces.
Author Contributions
The authors made equal contributions to this paper.
Funding
This research was supported by the Ministry of Science and Technology, Taiwan [grant number: 107-2115-M-037-001].
Acknowledgments
The authors of this paper are grateful to the referees for their valuable comments which improve the paper a lot.
Conflicts of Interest
The authors declare no conflict of interest.
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