Abstract
In this paper, we consider and study a system of multi-valued mixed variational inclusions with XOR-operation ⊕ in real ordered uniformly smooth Banach spaces. This system consists of bimappings, multi-valued mappings and Cayley operators. An iterative algorithm is suggested to find the solution to a system of multi-valued mixed variational inclusions with XOR-operation ⊕ and consequently an existence and convergence result is proved. In support of our main result, an example is constructed.
MSC:
47H05; 49H10; 47J25
1. Introduction
In 1964, Stampacchia [1] investigated the theory of variational inequality which provides us a lenient way for solving perplexities occurring in industry, finance, economics, operation research, optimization, decision sciences and several other branches of pure and applied sciences, and so forth, see, for example, [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. Hassouni and Moudafi [18] studied a mixed type variational inequality which involves a nonlinear term called variational inclusion. They used the resolvent operator technique in order to find the solution to their problem as the projection method does not work due to the nonlinear term.
A natural generalization of variational inequalities called the system of variational inequalities (inclusions) were considered and studied by several authors. Cohen and Chaplais [19], Ansari and Yao [20] and many more researchers considered various system of variational inequalities (inclusions), see also [21,22,23,24,25,26,27,28,29]. It has been shown by Pang [30] that not only the Nash equilibrium problem but also various equilibrium type problems, like the traffic equilibrium problem, spatial equilibrium problem and the general equilibrium programming problems from operation research, game theory, mathematical physics, and so forth, can be formulated as a variational inequality problem defined over a product of sets, which is equivalent to a system of variational inequalities.
Agarwal et al. [31] studied a system of generalized nonlinear mixed quasi-variational inclusions and demonstrated sensitivity analysis of their problem. Some ordered variational inclusions involving XOR-operation ⊕ are studied by Li et al. [32,33,34,35], Ahmad et al. [36,37,38,39] and Ali et al. [40] and so forth. For some related work, see also [41].
In this paper, we consider and study a system of multi-valued mixed variational inclusions with XOR-operation ⊕ in real ordered uniformly smooth Banach spaces. We prove the existence of solutions to a system of multi-valued mixed variational inclusions with XOR-operation ⊕ and we discuss the convergence of the iterative sequences generated by the proposed algorithm. An example is provided.
2. Preliminaries
Let E be a real ordered uniformly smooth Banach space with norm and be its topological dual. We denote by d the metric induced by the norm on E, by (respectively, ) the family of all nonempty closed and bounded subsets (respectively, the set of all nonempty subsets) of E and by the Hausdörff metric on Let be a cone. For arbitrary elements , holds if and only if , then the relation in E is called partial order relation induced by the cone C.
Let be the duality pairing between E and , and be the normalized duality mapping defined by
We recall some well known concepts and results for the presentation of this paper.
The modulus of smoothness of a Banach space E is a function defined by
A Banach space E is called uniformly smooth if
Definition 1
([29]). A mapping is said to be
- (i)
- accretive, if for any , there exists such that
- (ii)
- strongly accretive, if for any , there exists and a constant such that
- (iii)
- Lipschitz continuous, if for any , there exists a constant such that
Proposition 1
([42]). Let E be a uniformly smooth Banach space and be a normalized duality mapping. Then, for any ,
- (i)
- for all ,
- (ii)
- where .
Definition 2.
A multi-valued mapping is said to be D-Lipschitz continuous, if for any , there exists a constant such that
Definition 3.
A cone C is said to be normal if there exists a constant such that for , , where is normal constant of C.
Definition 4.
For arbitrary element , (or ) holds, then x and y said to be comparable to each other (denoted by ).
Most of the following definitions can be found in [43].
Definition 5.
For arbitrary elements x,y of E, and mean the least upper bound and the greatest lower bound of the set . Suppose and exist. Then some binary operations are defined as follows:
- (i)
- ,
- (ii)
- ,
- (iii)
- ,
- (iv)
- .
The operations and ⊙ are called and operations, respectively.
Proposition 2.
Let ⊕ be an XOR-operation and ⊙ be an XNOR -operation. Then the following relations hold:
- (i)
- (ii)
- if then
- (iii)
- if
- (iv)
- if then if and only if
Proposition 3
([43]). Let be a normal cone with normal constant . Then for each x,y of E, the following relations hold:
- (i)
- (ii)
- (iii)
- (iv)
- if then
Definition 6
([33]). Let be a single-valued mapping. Then
- (i)
- A is said to be a comparison mapping, if for all then and
- (ii)
- A is said to be strongly comparison mapping, if A is a comparison mapping and if and only if for all
- (iii)
- A is said to be -ordered compression mapping, if A is a comparison mapping, and
Definition 7
([32,39]). Let be a multi-valued mapping. Then
- (i)
- M is said to be a comparison mapping, if for any and if , then for any and any for all ,
- (ii)
- M is said to be -non-ordinary difference mapping, if for all , M is a comparison mapping and and such that
- (iii)
- M is said to λ-XOR-ordered strongly monotone mapping, if then there exists a constant such that
Definition 8.
Let be a strong comparison and -ordered compression mapping. Then, a comparison multi-valued mapping is said to be -XOR-NODSM , if M is -non-ordinary difference mapping and λ-XOR-ordered strongly monotone mapping such that , for all .
Definition 9.
Let be a strongly comparison and -ordered compression mapping and let be a multi-valued, -XOR-NODSM mapping. The resolvent operator associated with A and M is defined by
It is proved in [39] that the resolvent operator defined by (1) is a single-valued comparison as well as -Lipschitz-type continuous, where
Definition 10.
One can easily prove that the Cayley operator defined by (2) is single-valued, a comparison as well as -Lipschitz-type continuous, where is same as in Definition 9, for more details see [40].
3. A System of Multi-Valued Mixed Variational Inclusions with XOR-Operation ⊕ and an Iterative Algorithm
Let E be a real ordered uniformly smooth Banach space. Let be multi-valued mappings and ; be single-valued mappings. Let be multi-valued mappings and be Cayley operators. We deal with the following problem.
Find such that
where and are constants. Problem (3) is called system of multi-valued mixed variational inclusions with XOR-operation ⊕.
If , then we encounter with the following problem, that is, find such that
Problem (4) appears to be the new one.
If , and ⊕ is replaced by +, then problem (4) reduces to the problem of finding such that
Problem (5) is considered in [26] in the setting of Hilbert spaces.
It is easy to check that problem (3) includes many previously studied problems related to variational inclusions.
The following Lemma is a fixed point formulation of problem (3).
Lemma 1.
is a solution to a system of multi-valued mixed variational inclusions with XOR-operation ⊕ (3), if and only if the following equations are satisfied:
where, and are constants.
Proof.
The proof is easy and hence omitted. ☐
Since and , by Nadler’s theorem [44], there exist and such that
where D is the Hausdörff metric on . Let
and
Again by Nadler’s theorem [44], there exist and such that
In a similar way, we can compute the sequences and by the following scheme:
and
for
Choose such that
4. Existence of Solutions and Convergence of Iterative Sequences
We prove the following existence and convergence result for problem (3).
Theorem 1.
Let E be a real ordered uniformly smooth Banach space with modulus of smoothness for some and be a normal cone with normal constant . Let ; be single-valued mappings such that A is strongly comparison and -ordered compression mapping; S is Lipschitz continuous in both the arguments with constant and , respectively; T is Lipschitz continuous in both the arguments with constant and , respectively. Let be multi-valued mappings such that F is -D-Lipschitz continuous and G is -D-Lipschitz continuous. Suppose that be single-valued mappings such that P is -strongly accretive and -Lipschitz continuous; q is -strongly accretive and -Lipschitz continuous. Let be -XOR-NODSM mapping and be -XOR-NODSM mapping. Suppose that the resolvent operators are θ-Lipschitz-type continuous and -Lipschitz-type continuous, respectively, and the Cayley operators are and -Lipschitz-type continuous, respectively. Let and for some the following conditions are satisfied:
where
Then, the system of multi-valued mixed variational inclusions with XOR-operation ⊕ (3) have a solution where such that and strongly, where and are the sequences generated by Algorithm 1.
Proof.
As , using of Proposition 2 and (8) of Algorithm 1, we have
Since the resolvent operator is Lipschitz-type-continuous with constant and A is -compression mapping, we evaluate
Using (iii) of Proposition 3 and (20), we have
Using the Lipschitz continuity of S in both the arguments with constants and , respectively, and using (iii) of Proposition 3, we obtain
Using D-Lipschitz continuity of F, we have
Since P is strongly accretive with constant and Lipschitz continuous with constant , using the techniques of Alber and Yao [45] and Proposition 1, for , we have
where .
Since the Cayley operator is Lipschitz-type-continuous with constant and using (iii) of Proposition 3, we obtain
where
As , using of Proposition 2 and (9) of Algorithm 1, we have
Since the resolvent operator is Lipschitz-type-continuous with constant and A is -compression mapping, we evaluate
Combining (27) and (28), we have
Using (iii) of Proposition 3 and (29), we have
Using Lipschitz continuity of T in both the arguments with constant and , respectively using (iii) of Proposition 3, we obtain
Using D-Lipschitz continuity of G, we have
Since q is strongly accretive and Lipschitz continuous, using the same techniques as for (24), we have
where
Since the Cayley operator is Lipschitz-type-continuous with constant , we obtain
where
As and combining (31) to (34) with (30), we have
Combining (26) and (35), we have
where
Let
Conditions (12) and (13) imply that and so , when n is sufficiently large. It follows from (36) that and are both Cauchy sequences. Thus, we can assume that and , strongly.
It follows from (23) and (32), that and are also Cauchy sequences, we can assume that and , strongly.
Now we shown that as , since , we have
Hence , so as . Similarly, we can show that . By Lemma 1, we conclude that is a solution to a system of multi-valued mixed variational inclusions with XOR-operation ⊕ (3). ☐
The following example shows that all the assumptions and conditions of Theorem 1 are satisfied.
Example 1.
Let with the usual inner product and be a normal cone with normal constant . Suppose that , , are single valued mappings and be resolvent operators and Cayley operators, respectively, for some .
Let and be multi-valued mappings. Then, we define all the mappings mentioned above as:
- (1)
- Clearly, A is strongly comparison mapping andThat is, A is -ordered compression mapping.
- (2)
- It is easy to check that S is Lipschitz continuous in both the arguments with constants and respectively and T is Lipschitz continuous in both the arguments with constants 1 and , respectively.
- (3)
- For , we calculateand Thus, P is strongly accretive with constant and Lipschitz continuous with constant .Similarly, we can show that q is strongly accretive with constant and Lipschitz continuous with constant .
- (4)
- One can easily show that the resolvent operators is -Lipschitz-type-continuous, is -Lipschitz type continuous, the Cayley operators is -Lipschitz-type continuous and is -Lipschitz-type-continuous.Also, M is a comparison mapping and 2-non-ordinary difference mapping, N is a comparison mapping and 3-non-ordinary difference mapping.Let and , thenFor , and for , . This shows that M is -XOR-NODSM mapping and N is -XOR-NODSM mapping.
- (5)
- Clearly, F and G are D-Lipschitz continuous mappings with constants 2 and 3 respectively.
- (6)
- We choose and and we claim that the conditions (12) and (13) are satisfied.That is,andThus, all the assumptions and conditions of Theorem 1 are satisfied.
Author Contributions
All the authors have contributed equally to this paper. All the authors read and approved the final manuscript.
Funding
This research received no external funding.
Acknowledgments
The authors are thankful to anonymous referees and the editor for their valuable suggestions and comments which improve the manuscript a lot
Conflicts of Interest
The authors declare no conflict of interest.
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