Hindawi Publishing Corporation Fixed Point Theory and Applications Volume 2011, Article ID 635030, 13 pages doi:10.1155/2011/635030 Research Article Variational-Like Inclusions and Resolvent Equations Involving Infinite Family of Set-Valued Mappings Rais Ahmad and Mohd Dilshad Department of Mathematics, Aligarh Muslim University, Aligarh 202002, India Correspondence should be addressed to Rais Ahmad, raisain 123@rediffmail.com Received 18 December 2010; Accepted 23 December 2010 Academic Editor: Qamrul Hasan Ansari Copyright q 2011 R. Ahmad and M. Dilshad. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We study variational-like inclusions involving infinite family of set-valued mappings and their equivalence with resolvent equations. It is established that variational-like inclusions in real Banach spaces are equivalent to fixed point problems. This equivalence is used to suggest an iterative algorithm for solving resolvent equations. Some examples are constructed. 1. Introduction The important generalization of variational inequalities, called variational inclusions, have been extensively studied and generalized in different directions to study a wide class of problems arising in mechanics, optimization, nonlinear programming, economics, finance and applied sciences, and so forth; see, for example 1–7 and references theirin. The resolvent operator technique for solving variational inequalities and variational inclusions is interesting and important. The resolvent operator technique is used to establish an equivalence between variational inequalities and resolvent equations. The resolvent equation technique is used to develop powerful and efficient numerical techniques for solving various classes of variational inequalities inclusions and related optimization problems. In this paper, we established a relationship between variational-like inclusions and resolvent equations. We propose an iterative algorithm for computing the approximate solutions which converge to exact solution of considered resolvent equations. Some examples are constructed. 2 Fixed Point Theory and Applications 2. Formulation and Preliminaries Throughout the paper, unless otherwise specified, we assume that E is a real Banach space with its norm · , E∗ is the topological dual of E, ·, · is the pairing between E and E∗ , d is the metric induced by the norm · , 2E resp., CBE is the family of nonempty resp., nonempty closed and bounded subsets of E, and H·, · is the Housdorff metric on CBE defined by HP, Q max sup dx, Q, sup d P, y x∈P where dx, Q infy∈Q dx, y and dP, y ∗ mapping J : E → 2E is defined by , 2.1 y∈Q infx∈P dx, y. The normalized duality Jx f ∈ E∗ : x, f x · f , f x, ∀x ∈ E . 2.2 Definition 2.1. Let E be a real Banach space. Let η : E × E → E; g, A : E → E be the singlevalued mapping, and let M : E → 2E be a set-valued mapping. Then, i the mapping g is said to be accretive if gx − g y , j x − y ≥ 0, ∀x, y ∈ E, 2.3 ∀x, y ∈ E, 2.4 ii the mapping g is said to be strictly accretive if gx − g y , j x − y ≥ 0, and the equality hold if and only if x y, iii the mapping g is said to be k-strongly accretive k ∈ 0, 1 if for any x, y ∈ E, there exists jx − y ∈ Jx − y such that gx − g y , j x − y ≥ k x − y 2 , 2.5 iv the mapping A is said to be r-strongly η-accretive, if there exists a constant r > 0 such that Ax − A y , j η x, y ≥r x−y 2 , ∀x, y ∈ E, 2.6 v the mapping M is said to be m-relaxed η-accretive, if there exists a constant m > 0 such that u − v, j η x, y ≥ −m x − y 2 , ∀x, y ∈ E, u ∈ Mx, v ∈ M y . 2.7 Fixed Point Theory and Applications 3 Definition 2.2. Let A : E → E, η : E × E → E be the single-valued mappings. Then, a set-valued mapping M : E → 2E is called A, η-accretive if M is m-relaxed ηaccretive and A ρME E, for every ρ > 0. ∗ Proposition 2.3 see 8, 9. Let E be a real Banach space, and let J : E → 2E be the normalized duality mapping. Then, for any x, y ∈ E x y 2 ≤ x2 2 y, j x y , ∀j x y ∈J x y . 2.8 Definition 2.4. Let A : E → E, W : E × E → E, and let N : E∞ E × E × E · · · → E be the mappings. Then, i the mapping A is said to be Lipschitz continuous with constant λA if Ax − A y ≤ λA x − y , ∀x, y ∈ E, 2.9 ii the mapping W is said to be Lipschitz continuous in the first argument with constant λW1 if Wx1 , · − Wx2 , · ≤ λW1 x1 − x2 , ∀x1 , x2 ∈ E. 2.10 Similarly, we can define Lipschitz continuity in the second argument. iii the mapping N is said to be Lipschitz continuous in the ith argument with constant βi if N·, . . . , xi , . . . − N ·, . . . , yi , . . . ≤ βi xi − yi , ∀xi , yi ∈ E. 2.11 Definition 2.5. Let A : E → E be a strictly η-accretive mapping, and let M : E → 2E be an ρ,A A, η-accretive mapping. Then, the resolvent operator Jη,M : E → E is defined by ρ,A Jη,M u A ρM −1 u, ∀u ∈ E. 2.12 Proposition 2.6 see 10. Let E be a real Banach space, and let η : E × E → E be τ-Lipschitz continuous; let A : E → E be an r-strongly η-accretive mapping, and let M : E → 2E be an A, ηρ,A accretive mapping. Then the resolvent operator Jη,M : E → E is τ/r − ρm-Lipschitz continuous, that is, ρ,A ρ,A Jη,M x − Jη,M y ≤ where ρ ∈ 0, r/m is a constant. τ x−y , r − ρm ∀x, y ∈ E, 2.13 4 Fixed Point Theory and Applications Example 2.7. Let E Ê, Ax Then, M is η-accretive. √ √ √ √ x, My y, and ηx, y x − y for all x, y ≥ 0 ∈ E. Example 2.8. Let M·, · : E × E → 2E be r-strongly η-accretive in the first argument. Then, M is m-relaxed η-accretive for m ∈ 1, r r 2 , for r > 0.6180. Let Ti : E → CBE, i 1, 2, . . . , ∞ be an infinite family of set-valued mappings, and let N : E∞ E×E×E · · · → E be a nonlinear mapping. Let η, W : E×E → E; A, g, m : E → E be single-valued mappings, let and B, C, D:E → CBE be set-valued mappings. Suppose that M·, · : E × E → 2E is A, η-accretive mapping in the first argument. We consider the following problem. Find u ∈ E, wi ∈ Ti u, i 1, 2, . . . , ∞, a ∈ Bu, x ∈ Cu, and y ∈ Du such that 0 ∈ Nw1 , w2 , . . . − W x, y ma M gu − ma, u . 2.14 The problem 2.14 is called variational-like inclusions problem. Special Cases i If W 0, m 0, then problem 2.14 reduces to the problem of finding u ∈ E, wi ∈ Ti u, i 1, 2, . . . , ∞ such that 0 ∈ Nw1 , w2 , . . . M gu, u . 2.15 Problem 2.15 is introduced and studied by Wang 11. ii If W 0, m 0, N·, . . . N·, ·, then problem 2.14 reduces to a problem considered by Chang, et al. 12, 13 that is, find u ∈ H, w1 ∈ T1 u, w2 ∈ T2 u such that M gu, u . 0 ∈ Nw1 , w2 2.16 It is now clear that for a suitable choice of maps involved in the formulation of problem 2.14, we can drive many known variational inclusions considered and studied in the literature. In connection with problem 2.14, we consider the following resolvent equation problem. Find z, u ∈ E, wi ∈ Ti u, i 1, 2, . . . , ∞; a ∈ Bu, x ∈ Cu, y ∈ Du such that Nw1 , w2 , . . . − W x, y ρ,A ma ρ,A ρ,A ρ−1 Rη,M·,u z 0, ρ,A 2.17 ρ,A where ρ is a constant and Rη,M·,u I − AJη,M·,u , where AJη,M·,uz AJη,M·,u z and I is the identity mapping. Equation 2.17 is called the resolvent equation problem. Fixed Point Theory and Applications 5 In support of problem 2.17, we have the following example. Example 2.9. Let us suppose that E Ê, Ti u −i, i, i 1, 2, . . . , ∞, Cu {π/2}, Bu 0, 1, and Du {1}. We define for wi ∈ Ti u, i 1, 2, . . . , ∞, a ∈ Bu, x ∈ Cu and y ∈ Du. i Nw1 , w2 , . . . min{−1, sin w1 , sin w2 , . . .}, ii ma sin−1 a cos−1 a, iii Wx, y xy, iv Ax x − 1, for all x ∈ Ê, v M·, x 1, for all x ∈ Ê, Then, for ρ 1, it is easy to check that the resolvent equation problem 2.17 is satisfied. 3. An Iterative Algorithm and Convergence Result We mention the following equivalence between the problem 2.14 and a fixed point problem which can be easily proved by using the definition of resolvent operator. Lemma 3.1. Let u, a, x, y, w1 , w2 , . . . where u ∈ E, wi ∈ Ti u, i 1, 2, . . . , ∞, a ∈ Bu, x ∈ Cu, and y ∈ Du, is a solution of 2.14 if and only if it is a solution of the following equation: gu ma ρ,A Jη,M·,u A gu − ma − ρ Nw1 , w2 , . . . − W x, y ma . 3.1 Now, we show that the problem 2.14 is equivalent to a resolvent equation problem. Lemma 3.2. Let u ∈ E, wi ∈ Ti u, i 1, 2, . . . , ∞, a ∈ Bu, x ∈ Cu, y ∈ Du, then the following are equivalent: i u, a, x, y, w1 , w2 , . . . is a solution of variational inclusion problem 2.14, ii z, u, a, x, y, w1 , w2 , . . . is a solution of the problem 2.17, where z A gu − ma − ρ Nw1 , w2 , . . . − W x, y gu ma ma , ρ,A Jη,M·,u A gu − ma − ρ Nw1 , w2 , . . . − W x, y 3.2 ma . 6 Fixed Point Theory and Applications Proof. Let u, a, x, y, w1 , w2 , . . . be a solution of the problem 2.14, then by Lemma 3.1, it is a solution of the problem ρ,A Jη,M·,u A gu − ma − ρ Nw1 , w2 , . . . − W x, y gu ma 3.3 ma , using the fact that ρ,A ρ,A Rη,M·,u I − A Jη,M·,u , ρ,A ρ,A Rη,M·,u z Rη,M·,u A gu − ma − ρ Nw1 , w2 , . . . − W x, y ρ,A I − A Jη,M·,u ma A gu − ma − ρNw1 , w2 , . . . − W x, y A gu − ma − ρ Nw1 , w2 , . . . − W x, y ma ma ρ,A − A Jη,M·,u A gu − ma − ρ Nw1 , w2 , . . . − W x, y A gu − ma − ρ Nw1 , w2 , . . . − W x, y − A gu − ma , ma ma 3.4 which implies that Nw1 , w2 , . . . − W x, y ma ρ−1 Rη,M·,u z 0, ρ,A 3.5 with z A gu − ma − ρ Nw1 , w2 , . . . − W x, y 3.6 ma , that is, z, u, a, x, y, w1 , w2 , . . . is a solution of problem 2.17. Conversly, let z, u, a, x, y, w1 , w2 , . . . be a solution of problem 2.17, then ρ Nw1 , w2 , . . . − W x, y ρ Nw1 , w2 , . . . − W x, y ρ,A ma −Rη,M·,u z, 3.7 ρ,A ma A Jη,M·,u z − z, from 3.2 and 3.7, we have ma ρ Nw1 , w2 , . . . − W x, y ρ,A A Jη,M·,u A gu − ma − ρ Nw1 , w2 , . . . − W x, y − A gu − ma − ρ Nw1 , w2 , . . . − W x, y ma , ma 3.8 Fixed Point Theory and Applications 7 which implies that gu ma ρ,A Jη,M·,u A gu − ma − ρ Nw1 , w2 , . . . − W x, y ma , 3.9 that is, u, a, x, y, w1 , w2 , . . . is a solution of 2.14. We now invoke Lemmas 3.1 and 3.2 to suggest the following iterative algorithm for solving resolvent equation problem 2.17. Algorithm 3.3. For a given z0 , u0 ∈ E, wi0 ∈ Ti u0 , i 1, 2, . . . , ∞, a0 ∈ Bu0 , x0 ∈ Cu0 , and y0 ∈ Du0 . Let z1 A gu0 − ma0 − ρ N w10 , w20 , . . . − W x0 , y0 ma0 . 3.10 Take z1 , u1 ∈ E such that gu1 ma1 ρ,A 3.11 Jη,M·,u1 z1 . Since for each i, wi0 ∈ Ti u0 , a0 ∈ Bu0 , x0 ∈ Cu0 , and y0 ∈ Du0 by Nadler’s theorem 14 there exist wi1 ∈ Ti u1 , a1 ∈ Bu1 , x1 ∈ Cu1 , and y1 ∈ Du1 such that wi0 − wi1 ≤ HTi u0 , Ti u1 , a0 − a1 ≤ HBu0 , Bu1 , 3.12 x0 − x1 ≤ HCu0 , Cu1 , y0 − y1 ≤ HDu0 , Du1 , where H is the Housdorff metric on CBE. Let z2 A gu1 − ma1 − ρ N w11 , w21 , . . . − W x1 , y1 ma1 , 3.13 and take any u2 ∈ E such that gu2 ma2 ρ,A Jη,M·,u2 z2 . Continuing the above process inductively, we obtain the following. 3.14 8 Fixed Point Theory and Applications For any z0 , u0 ∈ E, wi0 ∈ Ti u0 , i 1, 2, . . . , ∞, a0 ∈ Bu0 , x0 ∈ Cu0 , and y0 ∈ Du0 . Compute the sequences {zn }, {un }, {win }, i 1, 2, . . . , ∞, {a0 }, {x0 }, {y0 } by the following iterative schemes: ρ,A i gun man ii an ∈ Bun , an − an 1 ≤ HBun , Bun 1 , iii xn ∈ Cun , yn − yn 1 v for each i, win ∈ Ti un , 1 3.16 xn − xn 1 ≤ HCun , Cun 1 , iv yn ∈ Dun , vi zn 3.15 Jη,M·,un zn , 3.17 ≤ HDun , Dun 1 , win − win 1 3.18 3.19 ≤ HTi un , Ti un 1 , A gun − man − ρ N w1n , w2n , . . . − W xn , yn man , 3.20 where ρ > 0 is a constant and n 0, 1, 2, . . .. Theorem 3.4. Let E be a real Banach space. Let Ti , B, C, D : E → CBE be H-Lipschitz continuous mapping with constants δi , α, t, γ , respectively. Let N E∞ E × E × E · · · → E be Lipschitz continuous with constant βi , let A, g, m : E → E be Lipschitz continuous with constants λA , λg , λm , respectively, and let A be r-strongly η-accretive mapping. Suppose that η,W : E×E → E are mappings such that η is Lipschitz continuous with constant τ and W is Lipschitz continuous in both the argument with constant λW1 and λW2 , respectively. Let M : E × E → 2E be A, η-accretive mapping in the first argument such that the following holds for μ > 0: ρ,η ρ,η JM·,un zn − JM·,un−1 zn ≤ μun − un−1 . 3.21 Suppose there exists a ρ > 0 such that λA λg λm α λA ρ ρ ∞ βi δi ρ λ W1 t λ W2 γ i1 r − ρm < 1 − λ2m α2 τ μ2 − 2k , r m < , λ2m α2 < 1 ρ 3.22 2k − μ . 2 Then, there exist z, u, ∈ E, a ∈ BE, and x ∈ CE, y ∈ DE, and wi ∈ Ti u that satisfy resolvent equation problem 2.17. The iterative sequences {zn }, {un }, {an } {xn }, {yn }, and {win }, i 1, 2, . . . , ∞, n 0, 1, . . . generated by Algorithm 3.3 converge strongly to z, u, a, x, y, wi , respectively. Fixed Point Theory and Applications 9 Proof. From Algorithm 3.3, we have zn 1 − zn A gun − man − ρ N w1n , w2n , . . . − W xn , yn man − A gun−1 − man−1 − ρ N w1n−1 , w2n−1 , . . . − W xn−1 , yn−1 man−1 ≤ A gun − man − A gun−1 − man−1 3.23 ρ N w1n , w2n , . . . − N w1n−1 , w2n−1 , . . . ρ W xn , yn − W xn−1 , yn−1 ρman − man−1 . By using the Lipschitz continuty of A, g, and m with constants λA , λg , and λm , respectively, and by Algorithm 3.3, we have A gun − man − A gun−1 − man−1 ≤ λA gun − gun−1 λA man − man−1 ≤ λA λg un − un−1 λA λm an − an−1 ≤ λA λg un − un−1 λA λm HBun , Bun−1 3.24 ≤ λA λg un − un−1 λA λm αun − un−1 λA λg λA λm α un − un−1 . Since N is Lipschitz continuous in all the arguments with constant βi , i 1, 2, . . ., respectively, and using H-Lipschitz continuity of Ti ’s with constant δi , we have N w1n , w2n , . . . − N w1n−1 , w2n−1 , . . . N w1n , w2n , . . . − N w1n−1 , w2n , . . . N w1n−1 , w2n , . . . ≤ N w1n , w2n , . . . − N w1n−1 , w2n , . . . N w1n−1 , w2n , . . . − N w1n−1 , w2n−1 , . . . ≤ β1 w1n − w1n−1 β2 w2n − w2n−1 ··· ··· ··· 10 Fixed Point Theory and Applications ≤ ∞ βi win − win−1 i1 ≤ ∞ βi HTi un , Ti un−1 i1 ≤ ∞ βi δi un − un−1 , n 0, 1, 2, . . . . i1 3.25 Since W is a Lipschitz continuous in both the arguments with constant λW1 , λW2 respectively, and C and D are H-Lipschitz continuous with constant t and γ , respectively, we have W xn , yn − W xn−1 , yn−1 ≤ λW2 yn − yn−1 λW1 xn − xn−1 ≤ λW2 γ un − un−1 λ W1 t λW1 tun − un−1 3.26 λW2 γ un − un−1 . Combining 3.24, 3.25, and 3.26 with 3.23, we have zn 1 λA λm α un − un−1 − zn ≤ λA λg ρ ∞ βi δi un − un−1 i1 ρ λ W1 t λA λg λW2 γ un − un−1 λm α λA ρ ρ ρλm αun − un−1 ∞ βi δi ρ λ W1 t λ W2 γ 3.27 un − un−1 . i1 By using Proposition 2.3 and k-strong accretiveness of g, we have un − un−1 2 man ρ,η JM·,un zn − man−1 ρ,η − JM·,un−1 zn−1 − gun − un − gun−1 − un−1 ≤ man − man−1 2 ρ,η ρ,η JM·,un zn − JM·,un−1 zn−1 2 2 − 2 gun − un − gun−1 − un−1 , jun − un−1 ≤ man − man−1 2 ρ,η ρ,η JM·,un zn − JM·,un−1 zn ρ,η ρ,η JM·,un−1 zn − JM·,un−1 zn−1 − 2 gun − un − gun−1 − un−1 , jun − un−1 , 2 Fixed Point Theory and Applications 11 un − un−1 2 ≤ λ2m α2 un − un−1 2 ρ,η ρ,η ρ,η JM·,un zn − JM·,un−1 zn ρ,η JM·,un−1 zn − JM·,un−1 zn−1 2 2 − 2 gun − un − gun−1 − un−1 , jun − un−1 ≤ λ2m α2 un − un−1 2 2 un − un−1 ≤ τ r − ρm λ2m α2 2 μ2 un − un−1 2 zn − zn−1 2 − 2kun − un−1 2 , μ − 2k un − un−1 2 2 τ r − ρm 2 zn − zn−1 2 , 2 τ/ r − ρm un − un−1 ≤ zn − zn−1 2 , 2 2 2 1 − λm α μ − 2k 2 τ un − un−1 ≤ 2 2 r − ρm 1 − λm α μ2 − 2k zn − zn−1 . 3.28 Using 3.28, 3.27 becomes zn 1 − zn ≤ λA λg λm α λA ρ ρ ∞ ρ λ W1 t i1 βi δi r − ρm 1 − λ2m α2 μ2 − 2k that is, zn 1 λ W2 γ τ zn − zn−1 , 3.29 − zn ≤ θzn − zn−1 , where θ λA λg λm α λA ρ ρ ∞ ρ λ W1 t i1 βi δi r − ρm 1 − λ2m α2 μ2 − 2k λ W2 γ τ . 3.30 From 3.22, we have θ < 1, and consequently {zn } is a Cauchy sequence in E. Since E is a Banach space, there exists z ∈ E such that zn → z. From 3.28, we know that {un } is also a Cauchy sequence in E. Therefore, there exists u ∈ E such that un → u. Since the mappings Ti ’s, B, C and D are H-Lipschitz continuous, it follows from 3.16–3.19 of Algorithm 3.3 that {an }, {xn }, {yn }, and {win } are also Cauchy sequences. We can assume that win → wi , an → a, xn → x, and yn → y. 12 Fixed Point Theory and Applications Now, we prove that wi ∈ Ti u. In fact, since win ∈ Ti ui and dwi , Ti u ≤ wi − win ≤ wi − win d win , Ti u max sup d q2 , Ti u , sup d Ti u, q1 q2 ∈Ti un q1 ∈Ti u wi − win HTi un , Ti u ≤ wi − win δi un − un−1 −→ 0 3.31 n −→ ∞, which implies that dwi , Ti u 0. As Ti u ∈ CBE, we have wi ∈ Ti u, i 1, 2, . . . ∞. Finally, by the continuity of A, g, m, N, and W and by Algorithm 3.3, it follows that ma , A gun − man − ρ N w1n , w2n , . . . − W xn , yn −→ z A gu − ma − ρ Nw1 , w2 , . . . − W x, y ma n −→ ∞, zn 1 ρ,η ρ,η JM·,un zn gun − man −→ gu − ma JM·,u z 3.32 n −→ ∞. From 3.32, and Lemma 3.2, it follows that Nw1 , w2 , . . . − W x, y ma Nw1 , w2 , . . . − W x, y ρ,η ρ−1 z − A JM·,u z 0, ma ρ−1 RM·,u z 0, ρ,η 3.33 that is, z, u, a, x, y, w1 , w2 , . . . is a solution of resolvent equation poblem 2.17. Acknowledgment This work is supported by Department of Science and Technology, Government of India, under Grant no. SR/S4/MS: 577/09. References 1 R. Ahmad, A. H. Siddiqi, and Z. Khan, “Proximal point algorithm for generalized multivalued nonlinear quasi-variational-like inclusions in Banach spaces,” Applied Mathematics and Computation, vol. 163, no. 1, pp. 295–308, 2005. 2 R. Ahmad and Q. H. Ansari, “An iterative algorithm for generalized nonlinear variational inclusions,” Applied Mathematics Letters, vol. 13, no. 5, pp. 23–26, 2000. 3 R. P. Agarwal, N. J. Huang, and Y. J. Cho, “Generalized nonlinear mixed implicit quasi-variational inclusions with set-valued mappings,” Journal of Inequalities and Applications, vol. 7, no. 6, pp. 807– 828, 2002. 4 R. P. Agarwal, Y. J. Cho, and N. J. Huang, “Sensitivity analysis for strongly nonlinear quasi-variational inclusions,” Applied Mathematics Letters, vol. 13, no. 6, pp. 19–24, 2000. 5 S.-S Chang, Y. J. Cho, and H. Zhou, Iterative Methods for Nonlinear Operator Equations in Banach Spaces, Nova Science Publishers, Huntington, NY, USA, 2002. 6 J.-Y. Chen, N.-C. Wong, and J.-C. Yao, “Algorithm for generalized co-complementarity problems in Banach spaces,” Computers & Mathematics with Applications, vol. 43, no. 1-2, pp. 49–54, 2002. Fixed Point Theory and Applications 13 7 X. P. Ding and C. L. Luo, “Perturbed proximal point algorithms for general quasi-variational-like inclusions,” Journal of Computational and Applied Mathematics, vol. 113, no. 1-2, pp. 153–165, 2000. 8 Ram U. Verma, “On generalized variational inequalities involving relaxed Lipschitz and relaxed monotone operators,” Journal of Mathematical Analysis and Applications, vol. 213, no. 1, pp. 387–392, 1997. 9 Hong Kun Xu, “Inequalities in Banach spaces with applications,” Nonlinear Analysis. Theory, Methods & Applications, vol. 16, no. 12, pp. 1127–1138, 1991. 10 H.-Y. Lan, Y. J. Cho, and R. U. Verma, “Nonlinear relaxed cocoercive variational inclusions involving A, η-accretive mappings in Banach spaces,” Computers & Mathematics with Applications, vol. 51, no. 9-10, pp. 1529–1538, 2006. 11 Y.-H. Wang, “The infinite family of generalized set-valued quasi-variation inclusions in Banach spaces,” Acta Analysis Functionalis Applicata, pp. 1009–1327, 2008. 12 S. S. Chang, “Set-valued variational inclusions in Banach spaces,” Journal of Mathematical Analysis and Applications, vol. 248, no. 2, pp. 438–454, 2000. 13 S. S. Chang, J. K. Kim, and K. H. Kim, “On the existence and iterative approximation problems of solutions for set-valued variational inclusions in Banach spaces,” Journal of Mathematical Analysis and Applications, vol. 268, no. 1, pp. 89–108, 2002. 14 S. B. Nadler, “Multivalued contraction mappings,” Pacific Journal of Mathematics, vol. 30, pp. 475–488, 1996.