1 Introduction

Recently, some systems of variational inequalities, variational inclusions, complementarity problems, and equilibrium problems have been studied by many authors because of their close relations to some problems arising in economics, mechanics, engineering science and other pure and applied sciences. Among these methods, the resolvent operator technique is very important. Huang and Fang [1] introduced a system of order complementarity problems and established some existence results for the system using fixed point theory. Verma [2] introduced and studied some systems of variational inequalities and developed some iterative algorithms for approximating the solutions of the systems of variational inequalities. Cho et al. [3] introduced and studied a new system of nonlinear variational inequalities in Hilbert spaces. Further, the authors proved some existence and uniqueness theorems of solutions for the systems, and also constructed some iterative algorithms for approximating the solution of the systems of nonlinear variational inequalities, respectively.

Moreover, Fang et al. [4], Yan et al. [5], Fang and Huang [6] introduced and studied some new systems of variational inclusions involving H-monotone operators and (H,η)-monotone operators in Hilbert space, respectively. Using the corresponding resolvent operator technique associated with H-monotone operators, (H,η)-monotone operators, the authors proved the existence of solutions for the variational inclusion systems and constructed some algorithms for approximating the solutions of the systems and discussed convergence of the iteration sequences generated by the algorithms, respectively. Very recently, Lan et al. [7] introduced and studied a new system of nonlinear A-monotone multivalued variational inclusions in Hilbert spaces. By using the concept and properties of A-monotone operators, and the resolvent operator technique associated with A-monotone operators due to Verma [8], the authors constructed a new iterative algorithm for solving this system of nonlinear multivalued variational inclusions with A-monotone operators in Hilbert spaces and proved the existence of solutions for the nonlinear multivalued variational inclusion systems and the convergence of iterative sequences generated by the algorithm. For some related work, see, for example, [132] and the references therein.

On the other hand, Cao [33] introduced and studied a new system of generalized quasi-variational-like-inclusions applying the η-proximal mapping technique. Further, Agarwal and Verma [34] introduced and studied relative (A,η)-maximal monotone operators and discussed the approximation solvability of a new system of nonlinear (set-valued) variational inclusions involving (A,η)-maximal relaxed monotone and relative (A,η)-maximal monotone operators in Hilbert spaces based on a generalized hybrid iterative algorithm and the general (A,η)-resolvent operator method.

Inspired and motivated by the above works, the purpose of this paper is to consider the following new general system of set-valued variational inclusions involving relative (A,η)-maximal monotone operators in Hilbert spaces: Find ( x 1 , x 2 ,, x m ) H 1 × H 2 ×× H m and u i j U i j ( x j ) for any i,j=1,2,,m such that

0 F i ( u i 1 , u i 2 , , u i m ) + M i ( g i ( x i ) ) ,
(1.1)

where m is a given positive integer, F i : H 1 × H 2 ×× H m H i , A i : H i H i , g i : H i H i and η i : H i × H i H i are single-valued operators, U i j : H j 2 H j is a set-valued operator and M i : H i 2 H i is relative ( A i , η i )-maximal monotone.

We note that for appropriate and suitable choices of positive integer m, the operators F i , g i , A i , η i , M i , U i j , and H i for i,j=1,2,,m, one can know that the problem (1.1) includes a number of known general problems of variational character, including variational inequality (system) problems, variational inclusion (system) problems as special cases. For more details, see [131, 35] and the following examples.

Example 1.1 For i,j=1,2,,m, if U i j = T i j is single-valued operator, the problem (1.1) reduces to finding x j H j , such that

0 F i ( T i 1 x 1 , T i 2 x 2 , , T i m x m ) + M i ( g i ( x i ) ) .
(1.2)

Example 1.2 For i=1,2,,m, if H i =H and A i I, an identity operator, and M i = φ i , where φ i :HR{+} is proper and lower semi-continuous η i -subdifferentiable functional and φ i denotes η i -subdifferential operator, then the problem (1.1) reduces to finding x i H and u i j U i j ( x j ) for j=1,2,,m such that

F i ( u i 1 , u i 2 , , u i m ) , η i ( x , g i ( x i ) ) φ i ( g i ( x i ) ) φ i (x),xH.
(1.3)

The problem (1.3) is called a set-valued nonlinear generalized quasi-variational-like-inclusion system, which was considered and studied by Cao [33].

Example 1.3 When m=2 and g i I for i=1,2, then the problem (1.1) is equivalent to the following nonlinear set-valued variational inclusion system problem: Find ( x 1 , x 2 ) H 1 × H 2 and u 1 U 1 ( x 1 ), u 2 U 2 ( x 2 ) such that

0 F 1 ( x 1 , u 2 ) + M 1 ( x 1 ) , 0 F 2 ( u 1 , x 2 ) + M 2 ( x 2 ) ,
(1.4)

which was studied by Agarwal and Verma [34].

Example 1.4 If m=2 and M i ( x i )= φ i ( x i ), where φ i : H i R{+} is proper, convex, and lower semi-continuous functional and φ i denotes the subdifferential operator of φ i for all x i H i , i=1,2, then the problem (1.4) reduces to the following system of set-valued mixed variational inequalities: Find ( x 1 , x 2 ) H 1 × H 2 , u 1 U 1 ( x 1 ) and u 2 U 2 ( x 2 ) such that

F 1 ( x 1 , u 2 ) , x x 1 + φ 1 ( x ) φ 1 ( x 1 ) 0 , x H 1 , F 2 ( u 1 , x 2 ) , y x 2 + φ 2 ( y ) φ 2 ( x 2 ) 0 , y H 2 .
(1.5)

If U 1 = U 2 I, then the problem (1.5) reduces to finding ( x 1 , x 2 ) H 1 × H 2 such that

F 1 ( x 1 , x 2 ) , x x 1 + φ 1 ( x ) φ 1 ( x 1 ) 0 , x H 1 , F 2 ( x 1 , x 2 ) , y x 2 + φ 2 ( y ) φ 2 ( x 2 ) 0 , y H 2 ,
(1.6)

which is called the system of nonlinear variational inequalities considered by Cho et al. [3]. Some specializations of the problem (1.6) are dealt by Kim and Kim [35].

Example 1.5 If m=2 and U 1 = U 2 = g 1 = g 2 I, then the problem (1.1) reduces to the problem of finding ( x 1 , x 2 ) H 1 × H 2 such that

0 F 1 ( x 1 , x 2 ) + M 1 ( x 1 ) , 0 F 2 ( x 1 , x 2 ) + M 2 ( x 2 ) ,

which was introduced and studied by Fang et al. [4].

Moreover, by using the generalized resolvent operator technique associated with relative (A,η)-maximal monotone operators, we also construct some new iterative algorithms for finding approximation solutions to the general systems of set-valued variational inclusions and prove convergence of the sequences generated by the algorithms.

2 Preliminaries

Throughout, let H and H i (i=1,2,,m) be real Hilbert spaces and endowed with the norm and inner product ,. Let 2 H and C(H) denote the family of all the nonempty subsets of H and the family of all closed subsets of H, respectively.

Definition 2.1 Let T:HH be a single-valued operator. Then the map T is said to be

  1. (i)

    r-strongly monotone, if there exists a constant r>0 such that

    T ( x ) T ( y ) , x y r x y 2 ,x,yH;
  2. (ii)

    β-Lipschitz continuous, if there exists a constant β>0 such that

    TxTyβxy,x,yH.

Definition 2.2 Let η:H×HH and A:HH be single-valued operators, M:H 2 H be set-valued operator. Then

  1. (i)

    η is said to be t-strongly monotone, if there exists a constant t>0 such that

    η ( x , y ) , x y t x y 2 ,x,yH;
  2. (ii)

    η is said to be τ-Lipschitz continuous, if there exists a constant τ>0 such that

    η ( x , y ) τxy,x,yH;
  3. (iii)

    A is said to be η-monotone, if

    A ( x ) A ( y ) , η ( x , y ) 0,x,yH;
  4. (iv)

    A is said to be strictly η-monotone, if A is η-monotone and

    A ( x ) A ( y ) , η ( x , y ) =0if and only ifx=y;
  5. (v)

    A is said to be (r,η)-strongly monotone, if there exists a constant r>0 such that

    A ( x ) A ( y ) , η ( x , y ) r x y 2 ,x,yH;
  6. (vi)

    M is said to be η-monotone with respect to A (or relative (A,η)-monotone) if

    u v , η ( A ( x ) , A ( y ) ) 0,x,yH,uM(x),vM(y);
  7. (vii)

    M is said to be relative (A,η)-maximal monotone, if M is η-monotone with respect to A (or relative (A,η)-monotone) and (A+λM)(H)=H, where λ>0 is an arbitrary constant.

Definition 2.3 For i,j=1,2,,m, let H i be a Hilbert space, A j : H j H j be single-valued operator, U i j : H j 2 H j be set-valued operator. Then nonlinear operator F i : H 1 × H 2 ×× H m H i is said to be

  1. (i)

    ( U i j , c j , μ j )-relaxed cocoercive with respect to A j (or relative ( U i j , c j , μ j )-relaxed cocoercive) in the j th argument, if there exist constants c j , μ j >0 such that for all x j 1 , x j 2 H j , and for any u j 1 U i j ( x j 1 ), u j 2 U i j ( x j 2 ),

    F i ( , u j 1 , ) F i ( , u j 2 , ) , A j ( x j 1 ) A j ( x j 2 ) ( c j ) F i ( , u j 1 , ) F i ( , u j 2 , ) 2 + μ j x j 1 x j 2 2 ;
  2. (ii)

    ζ i j -Lipschitz continuous in the j th argument, if there exists constant ζ i j >0 such that for all x j , y j H j ,

    F i ( x 1 , , x j 1 , x j , x j + 1 , , x m ) F i ( x 1 , , x j 1 , y j , x j + 1 , , x m ) x j y j .

Remark 2.1

  1. (i)

    When m=1 and U=I, then (i) and (ii) of Definition 2.3 reduce to corresponding concept of the relative relaxed cocoerciveness and Lipschitz continuity, respectively.

  2. (ii)

    If U i j = T i j is single-valued operator for i,j=1,2,,m, then F i is ( U i j , c j , μ j )-relaxed cocoercive with respect to A j in the j th argument reduce to ( T i j , c j , μ j )-relaxed cocoercive with respect to A j in the j th argument, that is, if there exist constants c j , μ j >0 such that for all x j 1 , x j 2 H j ,

    F i ( , T i j x j 1 , ) F i ( , T i j x j 2 , ) , A j ( x j 1 ) A j ( x j 2 ) ( c j ) F i ( , T i j x j 1 , ) F i ( , T i j x j 2 , ) 2 + μ j x j 1 x j 2 2 .

Lemma 2.1 ([34])

Let η:H×HH be a single-valued mapping, A:HH be a strictly η-monotone mapping and M:H 2 H be a relative (A,η)-maximal monotone mapping. Then the mapping (A+λM) is single-valued, where λ>0 is arbitrary constant.

Definition 2.4 Let η:H×HH be a single-valued mapping, A:HH be a strictly η-monotone mapping and M:H 2 H be a relative (A,η)-maximal monotone mapping. Then generalized resolvent operator R M , λ A , η :HH is defined by

R M , λ A , η (z)= ( A + λ M ) 1 (z),zH,

where λ>0 is a constant.

Lemma 2.2 ([34])

Let η:H×HH be a t-strongly monotone and τ-Lipschitz continuous mapping, A:HH be an r-strongly monotone mapping, and M:H 2 H be a relative (A,η)-maximal monotone mapping. Then generalized resolvent operator R M , λ A , η :HH is τ r t -Lipschitz continuous, that is,

R M , λ A , η ( x ) R M , λ A , η ( y ) τ r t xy,x,yH.

Definition 2.5 A set-valued operator U:H 2 H is said to be D-γ-Lipschitz continuous, if there exists a constant γ>0 such that

D ( U ( x ) , U ( y ) ) γxy,x,yH,

where D:C(H)×C(H)R{+} is called the Hausdorff pseudo-metric defined as follows:

D(U,V)=max { sup x U inf y V x y , sup y V inf x U x y } ,U,VC(H).

Furthermore, the Hausdorff pseudo-metric D reduces to the Hausdorff metric when C(H) is restricted to closed bounded subsets of the family CB(H).

Lemma 2.3 Let θ(0,1) be a constant. Then function f(λ)=1λ+λθ for λ[0,1] is nonnegative and strictly decrease and f(λ)[0,1]. Further, if λ0, then f(λ)(0,1).

Lemma 2.4 ([36])

Let { a n } and { b n } be two nonnegative real sequences satisfying

a n + 1 θ a n + b n

with 0<θ<1 and lim n b n =0. Then lim n a n =0.

3 Iterative algorithm and convergence analysis

In this section, we construct a class of new iterative algorithms for finding approximate solutions of the problems (1.1) and (1.2), respectively. Then the convergence criterion for the algorithms is also discussed.

Lemma 3.1 Let ( x 1 , x 2 ,, x m ) H 1 × H 2 ×× H m and u i j U i j ( x j ) for i,j=1,2,,m, then ( x 1 , x 2 ,, x m , u 11 ,, u 1 m ,, u m 1 ,, u m m ) (denoted by ()) is a solution of the problem (1.1) if and only if () satisfy

g i ( x i ) = R M i , ρ i A i , η i [ A i ( g i ( x i ) ) ρ i F i ( u i 1 , , u i i 1 , u i i , u i i + 1 , , u i m ) ] ,
(3.1)

where R M i , ρ i A i , η i = ( A i + ρ i M i ) 1 and ρ i >0 is a constant for i=1,2,,m.

Proof It follows from the definition of generalized resolvent operator R M i , ρ i A i , η i that the proof can be obtained directly, and so it is omitted. □

Algorithm 3.1

Step 1. Setting ( x 1 0 , x 2 0 ,, x m 0 ) H 1 × H 2 ×× H m and choose u i j 0 U i j ( x j 0 ) for i,j=1,2,,m.

Step 2. Let

x i n + 1 = ( 1 λ ) x i n + λ { x i n g i ( x i n ) + R M i , ρ i A i , η i [ A i ( g i ( x i n ) ) ρ i F i ( u i 1 n , , u i i 1 n , u i i n , u i i + 1 n , , u i m n ) ] }
(3.2)

for all i=1,2,,m and n=0,1,2, , where λ(0,1] is a constant.

Step 3. By the results of Nadler [37], we can choose u i j n + 1 U i j ( x j n + 1 ) such that

u i j n + 1 u i j n ( 1 + 1 n + 1 ) D j ( U i j ( x j n + 1 ) , U i j ( x j n ) ) ,
(3.3)

where D j (,) is the Hausdorff pseudo-metric on C( H j ) and i,j=1,2,,m.

Step 4. If x i n + 1 and u i j n + 1 for i,j=1,2,,m satisfy (3.2) to sufficient accuracy, stop. Otherwise, set n:=n+1 and return to Step 2.

Remark 3.1 If R M i , ρ i A i , η i reduces to J ρ φ i = ( I + ρ φ i ) 1 , where φ i : H i R{+} is proper and lower semi-continuous η i -subdifferentiable functional, H i H for i=1,2,,m and λ=1, then Algorithm 3.1 reduces to Algorithm (I) of Cao [33].

When λ=1 and U i j = T i j is single-valued operator for i,j=1,2,,m, then Algorithm 3.1 reduces to the following algorithm for the problem (1.2).

Algorithm 3.2 For any given ( x 1 0 , x 2 0 ,, x m 0 ) H 1 × H 2 ×× H m , we compute x i n as follows:

x i n + 1 = x i n g i ( x i n ) + R M i , ρ i A i , η i [ A i ( g i ( x i n ) ) ρ i F i ( T i 1 x 1 n , , T i i 1 x i 1 n , T i i x i n , T i i + 1 x i + 1 n , , T i m x m n ) ] + w i n
(3.4)

for n=0,1,2, and i=1,2,,m, where w i n H i is error to take into account a possible inexact computation of the resolvent operator point satisfying conditions lim n w i n =0.

Remark 3.2

  1. (i)

    Let m=2, g i I, U i i I for i=1,2, then Algorithm 3.1 reduces to Algorithm 4.3 of Agarwal and Verma [34].

  2. (ii)

    If for appropriate and suitable choices of positive integer m and mappings F i , g i , A i , η i , M, U i j , and H i for i,j=1,2,,m, one can know that Algorithms 3.1-3.2 are extending a number of known algorithms.

In the sequel, we provide main result concerning the problem (1.1) with respect to Algorithm 3.1.

Theorem 3.1 For i=1,2,,m, let η i : H i × H i H i be τ i -Lipschitz continuous and t i -strongly monotone operator, A i : H i H i be β i -Lipschitz continuous and r i -strongly monotone operator, g i : H i H i be ξ i -Lipschitz continuous and δ i -strongly monotone operator and M i : H i 2 H i be relative ( A i , η i )-maximal monotone. Suppose that U i j : H j C H j is D j - γ i j -Lipschitz continuous, F i : H 1 × H 2 ×× H m H i is ( U i i , c i , μ i )-relaxed cocoercive with respect to A i in the ith argument and ζ i j -Lipschitz continuous in the jth for i,j=1,2,,m. If there exists constant ρ i >0 for such that

θ j = τ j r j t j β j 2 ξ j 2 2 ρ j μ j δ j 2 + 2 ρ j c j ζ j j 2 γ j j 2 + ρ j 2 ζ j j 2 γ j j 2 + 1 2 δ j + ξ j 2 + i = 1 , i j m ρ i τ i ζ i j γ i j r i t i < 1
(3.5)

for all j=1,2,,m, then the problem (1.1) admits a solution (), i.e. ( x 1 , x 2 ,, x m , u 11 ,, u 1 m ,, u m 1 ,, u m m ), where ( x 1 , x 2 ,, x m ) H 1 × H 2 ×× H m and u i j U i j ( x j ) for i,j=1,2,,m. Moreover, iterative sequences { x j n } and { u i j n } generated by Algorithm  3.1 strongly converge to x j and u i j for i,j=1,2,,m, respectively.

Proof For i=1,2,,m, applying Algorithm 3.1 and Lemma 2.2, we have

x i n + 1 x i n ( 1 λ ) x i n x i n 1 + λ x i n x i n 1 ( g i ( x i n ) g i ( x i n 1 ) ) + λ R M i , ρ i A i , η i [ A i ( g i ( x i n ) ) ρ i F i ( u i 1 n , , u i i 1 n , u i i n , u i i + 1 n , , u i m n ) ] R M i , ρ i A i , η i [ A i ( g i ( x i n 1 ) ) ρ i F i ( u i 1 n 1 , , u i i 1 n 1 , u i i n 1 , u i i + 1 n 1 , , u i m n 1 ) ] ( 1 λ ) x i n x i n 1 + λ x i n x i n 1 ( g i ( x i n ) g i ( x i n 1 ) ) + λ τ i r i t i A i ( g i ( x i n ) ) A i ( g i ( x i n 1 ) ) ρ i [ F i ( u i 1 n , , u i i 1 n , u i i n , u i i + 1 n , , u i m n ) F i ( u i 1 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) ] + λ τ i ρ i r i t i F i ( u i 1 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) F i ( u i 1 n 1 , , u i i 1 n 1 , u i i n 1 , u i i + 1 n 1 , , u i m n 1 ) .
(3.6)

By ξ i -Lipschitz continuity and δ i -strongly monotonicity of g i , we get

x i n x i n 1 ( g i ( x i n ) g i ( x i n 1 ) ) 2 = x i n x i n 1 2 2 g i ( x i n ) g i ( x i n 1 ) , x i n x i n 1 + g i ( x i n ) g i ( x i n 1 ) 2 ( 1 2 δ i + ξ i 2 ) x i n x i n 1 2 .
(3.7)

Since A i is β i -Lipschitz continuous, F i is ( U i i , c i , μ i )-relaxed cocoercive with respect to A i in the i th argument and F i is ζ i j -Lipschitz continuous in the j th argument, then we have

A i ( g i ( x i n ) ) A i ( g i ( x i n 1 ) ) ρ i [ F i ( u i 1 n , , u i i 1 n , u i i n , u i i + 1 n , , u i m n ) F i ( u i 1 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) ] 2 = A i ( g i ( x i n ) ) A i ( g i ( x i n 1 ) ) 2 2 ρ i F i ( u i 1 n , , u i i 1 n , u i i n , u i i + 1 n , , u i m n ) F i ( u i 1 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) , A i ( g i ( x i n ) ) A i ( g i ( x i n 1 ) ) + ρ i 2 F i ( u i 1 n , , u i i 1 n , u i i n , u i i + 1 n , , u i m n ) F i ( u i 1 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) 2 β i 2 g i ( x i n ) g i ( x i n 1 ) 2 2 ρ i [ ( c i ) F i ( u i 1 n , , u i i 1 n , u i i n , u i i + 1 n , , u i m n ) F i ( u i 1 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) 2 + μ i g i ( x i n ) g i ( x i n 1 ) 2 ] + ρ i 2 ζ i i 2 u i i n u i i n 1 2 ( β i 2 ξ i 2 2 ρ i μ i δ i 2 ) x i n x i n 1 2 + ( 2 ρ i c i ζ i i 2 + ρ i 2 ζ i i 2 ) u i i n u i i n 1 2 .
(3.8)

By D j - γ i j -Lipschitz continuity of the U i j and (3.3), we get

F i ( u i 1 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) F i ( u i 1 n 1 , , u i i 1 n 1 , u i i n 1 , u i i + 1 n 1 , , u i m n 1 ) F i ( u i 1 n , u i 2 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) F i ( u i 1 n 1 , u i 2 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) + + F i ( u i 1 n 1 , u i 2 n 1 , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) F i ( u i 1 n 1 , u i 2 n 1 , , u i i 1 n 1 , u i i n 1 , u i i + 1 n , , u i m n ) + F i ( u i 1 n 1 , u i 2 n 1 , , u i i 1 n 1 , u i i n 1 , u i i + 1 n , , u i m n ) F i ( u i 1 n 1 , u i 2 n 1 , , u i i 1 n 1 , u i i n 1 , u i i + 1 n 1 , , u i m n ) + + F i ( u i 1 n 1 , u i 2 n 1 , , u i i 1 n 1 , u i i n 1 , u i i + 1 n 1 , , u i m n ) F i ( u i 1 n 1 , u i 2 n 1 , , u i i 1 n 1 , u i i n 1 , u i i + 1 n 1 , , u i m n 1 ) ζ i 1 u i 1 n u i 1 n 1 + + ζ i i 1 u i i 1 n u i i 1 n 1 + ζ i i + 1 u i i + 1 n u i i + 1 n 1 + + ζ i m u i m n u i m n 1 = j = 1 , j i m ζ i j u i j n u i j n 1 j = 1 , j i m ζ i j ( 1 + 1 n ) D j ( U i j ( x j n ) , U i j ( x j n 1 ) ) ( 1 + 1 n ) j = 1 , j i m ζ i j γ i j x j n x j n 1
(3.9)

and

u i i n u i i n 1 ( 1 + 1 n ) D i ( U i i ( x i n ) , U i i ( x i n 1 ) ) ( 1 + 1 n ) γ i i x i n x i n 1 .
(3.10)

Combining (3.8) and (3.10), we have

A i ( g i ( x i n ) ) A i ( g i ( x i n 1 ) ) ρ i [ F i ( u i 1 n , , u i i 1 n , u i i n , u i i + 1 n , , u i m n ) F i ( u i 1 n , , u i i 1 n , u i i n 1 , u i i + 1 n , , u i m n ) ] 2 [ β i 2 ξ i 2 2 ρ i μ i δ i 2 + ( 1 + 1 n ) 2 γ i i 2 ( 2 ρ i c i ζ i i 2 + ρ i 2 ζ i i 2 ) ] x i n x i n 1 2 .
(3.11)

It follows from (3.6)-(3.9), and (3.11), that

x i n + 1 x i n ( 1 λ + λ 1 2 δ i + ξ i 2 ) x i n x i n 1 + λ τ i r i t i [ β i 2 ξ i 2 2 ρ i μ i δ i 2 + ( 1 + n 1 ) 2 γ i i 2 ( 2 ρ i c i ζ i i 2 + ρ i 2 ζ i i 2 ) x i n x i n 1 + ( 1 + 1 n ) ρ i j = 1 , j i m ζ i j γ i j x j n x j n 1 ] ,

which implies that

j = 1 m x j n + 1 x j n = i = 1 m x i n + 1 x i n i = 1 m [ ( 1 λ + λ 1 2 δ i + ξ i 2 ) x i n x i n 1 + λ τ i r i t i ( β i 2 ξ i 2 2 ρ i μ i δ i 2 + ( 1 + 1 n ) 2 γ i i 2 ( 2 ρ i c i ζ i i 2 + ρ i 2 ζ i i 2 ) x i n x i n 1 + ( 1 + 1 n ) ρ i j = 1 , j i m ζ i j γ i j x j n x j n 1 ) ] = i = 1 m [ ( 1 λ + λ 1 2 δ i + ξ i 2 ) + λ τ i r i t i β i 2 ξ i 2 2 ρ i μ i δ i 2 + ( 1 + 1 n ) 2 γ i i 2 ( 2 ρ i c i ζ i i 2 + ρ i 2 ζ i i 2 ) ] x i n x i n 1 + ( 1 + 1 n ) λ i = 1 m j = 1 , j i m ρ i τ i ζ i j γ i j r i t i x j n x j n 1 = j = 1 m [ ( 1 λ + λ 1 2 δ j + ξ j 2 ) + λ τ j r j t j β j 2 ξ j 2 2 ρ j μ j δ j 2 + ( 1 + 1 n ) 2 γ j j 2 ( 2 ρ j c j ζ j j 2 + ρ j 2 ζ j j 2 ) ] x j n x j n 1 + ( 1 + 1 n ) λ j = 1 m i = 1 , i j m ρ i τ i ζ i j γ i j r i t i x j n x j n 1 = j = 1 m [ ( 1 λ ) + λ ( 1 2 δ j + ξ j 2 + τ j r j t j β j 2 ξ j 2 2 ρ j μ j δ j 2 + ( 1 + 1 n ) 2 γ j j 2 ( 2 ρ j c j ζ j j 2 + ρ j 2 ζ j j 2 ) ) + ( 1 + 1 n ) i = 1 , i j m ρ i τ i ζ i j γ i j r i t i ] x j n x j n 1 = j = 1 m [ 1 λ + λ θ j n ] x j n x j n 1 f n ( λ ) j = 1 m x j n x j n 1 ,
(3.12)

where

θ j n = τ j r j t j β j 2 ξ j 2 2 ρ j μ j δ j 2 + ( 1 + 1 n ) 2 γ j j 2 ( 2 ρ j c j ζ j j 2 + ρ j 2 ζ j j 2 ) + 1 2 δ j + ξ j 2 + ( 1 + 1 n ) i = 1 , i j m ρ i τ i ζ i j γ i j r i t i

and

f n (λ)= max 1 j m { 1 λ + λ θ j n } .

By condition (3.5), we know that sequence { θ j n } is monotone decreasing and θ j n θ j as n. Thus,

f(λ)= lim n f n (λ)= max 1 j m {1λ+λ θ j }.

Since 0< θ j <1 for j=1,2,,m, we get θ= max 1 j m { θ j }(0,1), by Lemma 2.3, we have f(λ)=1λ+λθ(0,1). From (3.12), it follows that { x j n } is a Cauchy sequence and there exists x j H j such that x j n x j as n for j=1,2,,m.

Next, we show that u i j n u i j U i j ( x j ) as n for i,j=1,2,,m.

It follows from (3.9) and (3.10) that { u i j n } are also Cauchy sequences. Hence, there exists u i j H j such that u i j n u i j as n for i,j=1,2,,m. Furthermore,

d ( u i j , U i j ( x j ) ) = inf { u i j t : t U i j ( x j ) } u i j u i j n + d ( u i j n , U i j ( x j ) ) u i j u i j n + D j ( U i j ( x j n ) , U i j ( x j ) ) u i j u i j n + γ i j x j n x j 0 ( n ) .

Since U i j ( x j ) is closed for i,j=1,2,,m, we have u i j U i j ( x j ) for i,j=1,2,,m. Using continuity, ( x 1 , x 2 ,, x m ) H 1 × H 2 ×× H m and u i j U i j ( x j ) for i,j=1,2,,m satisfy (3.1) and so in light of Lemma 3.1, () is a solution to the problem (1.1). This completes the proof. □

Remark 3.3 If the generalized resolvent operator R M i , ρ i A i , η i reduces to J ρ φ i = ( I + ρ φ i ) 1 , where φ i : H i R{+} is proper and lower semi-continuous η i -subdifferentiable functional, H i =H for i=1,2,,m, λ=1 and ( U i i , c i , μ i )-relaxed cocoerciveness with respect to A i in the i th argument of F i reduces to μ i -( U i i , A i )-strongly monotonicity (right now, c i =0, A i g i ), then Theorem 3.1 reduces to Theorem 3.1 of Cao [33].

Theorem 3.2 Assume that η i , A i , g i , M i are the same as in the Theorem  3.1 for i=1,2,,m. Suppose that T i j : H j H j is γ i j -Lipschitz continuous, F i : H 1 × H 2 ×× H m H i is ( T i i , c i , μ i )-relaxed cocoercive with respect to A i in the ith argument and ζ i j -Lipschitz continuous in the jth for i,j=1,2,,m. If there exists constant ρ i >0 for such that

θ j = τ j r j t j β j 2 ξ j 2 2 ρ j μ j δ j 2 + 2 ρ j c j ζ j j 2 γ j j 2 + ρ j 2 ζ j j 2 γ j j 2 + 1 2 δ j + ξ j 2 + i = 1 , i j m ρ i τ i ζ i j γ i j r i t i < 1

for j=1,2,,m, then the problem (1.2) has a unique solution ( x 1 , x 2 ,, x m ) H 1 × H 2 ×× H m . Moreover, the iterative sequences { x j n } generated by Algorithm  3.2 strongly converge to x j for j=1,2,,m.

Proof Define the norm on product space H 1 × H 2 ×× H m by

( x 1 , x 2 , , x m ) = j = 1 m x j ,( x 1 , x 2 ,, x m ) H 1 × H 2 ×× H m .

It is easy to see that ( H 1 × H 2 ×× H m , ) is a Banach space. Set

y i = x i g i ( x i ) + R M i , ρ i A i , η i [ A i ( g i ( x i ) ) ρ i F i ( T i 1 x 1 , , T i i 1 x i 1 , T i i x i , T i i + 1 x i + 1 , , T i m x m ) ] .

Let G: H 1 × H 2 ×× H m H 1 × H 2 ×× H m be defined by

G( x 1 , x 2 ,, x m )=( y 1 , y 2 ,, y m ),( x 1 , x 2 ,, x m ) H 1 × H 2 ×× H m .

For any ( x 1 1 , x 2 1 ,, x m 1 ),( x 1 2 , x 2 2 ,, x m 2 ) H 1 × H 2 ×× H m , it follows from Lemma 2.2 that

G ( x 1 1 , x 2 1 , , x m 1 ) G ( x 1 2 , x 2 2 , , x m 2 ) = i = 1 m y i 1 y i 2 i = 1 m { x i 1 x i 2 ( g i ( x i 1 ) g i ( x i 2 ) ) + R M i , ρ i A i , η i [ A i ( g i ( x i 1 ) ) ρ i F i ( T i 1 x 1 1 , , T i i 1 x i 1 1 , T i i x i 1 , T i i + 1 x i + 1 1 , , T i m x m 1 ) ] R M i , ρ i A i , η i [ A i ( g i ( x i 2 ) ) ρ i F i ( T i 1 x 1 2 , , T i i 1 x i 1 2 , T i i x i 2 , T i i + 1 x i + 1 2 , , T i m x m 2 ) ] } i = 1 m { x i 1 x i 2 ( g i ( x i 1 ) g i ( x i 2 ) ) + τ i r i t i A i ( g i ( x i 1 ) ) A i ( g i ( x i 2 ) ) ρ i [ F i ( T i 1 x 1 1 , , T i i 1 x i 1 1 , T i i x i 1 , T i i + 1 x i + 1 1 , , T i m x m 1 ) F i ( T i 1 x 1 1 , , T i i 1 x i 1 1 , T i i x i 2 , T i i + 1 x i + 1 1 , , T i m x m 1 ) ] + τ i ρ i r i t i F i ( T i 1 x 1 1 , , T i i 1 x i 1 1 , T i i x i 2 , T i i + 1 x i + 1 1 , , T i m x m 1 ) F i ( T i 1 x 1 2 , , T i i 1 x i 1 2 , T i i x i 2 , T i i + 1 x i + 1 2 , , T i m x m 2 ) } .
(3.13)

By ξ i -Lipschitz continuity and δ i -strongly monotonicity of g i , we get

x i 1 x i 2 ( g i ( x i 1 ) g i ( x i 2 ) ) 1 2 δ i + ξ i 2 x i 1 x i 2 .
(3.14)

Since A i is β i -Lipschitz continuous, F i is ( T i i , c i , μ i )-relaxed cocoercive with respect to A i in the i th argument and F i is ζ i j -Lipschitz continuous in the j th argument and T i j : H j H j is γ i j -Lipschitz continuous, then we have

A i ( g i ( x i 1 ) ) A i ( g i ( x i 2 ) ) ρ i [ F i ( T i 1 x 1 1 , , T i i 1 x i 1 1 , T i i x i 1 , T i i + 1 x i + 1 1 , , T i m x m 1 ) F i ( T i 1 x 1 1 , , T i i 1 x i 1 1 , T i i x i 2 , T i i + 1 x i + 1 1 , , T i m x m 1 ) ] 2 β i 2 g i ( x i 1 ) g i ( x i 2 ) 2 2 ρ i [ ( c i ) F i ( T i 1 x 1 1 , , T i i 1 x i 1 1 , T i i x i 1 , T i i + 1 x i + 1 1 , , T i m x m 1 ) F i ( T i 1 x 1 1 , , T i i 1 x i 1 1 , T i i x i 2 , T i i + 1 x i + 1 1 , , T i m x m 1 ) 2 + μ i g i ( x i 1 ) g i ( x i 2 ) 2 ] + ρ i 2 ζ i i 2 T i i x i 1 T i i x i 2 2 ( β i 2 ξ i 2 2 ρ i μ i δ i 2 ) x i 1 x i 2 2 + ( 2 ρ i c i ζ i i 2 + ρ i 2 ζ i i 2 ) T i i x i 1 T i i x i 2 2 ( β i 2 ξ i 2 2 ρ i μ i δ i 2 + 2 ρ i c i ζ i i 2 γ i i + ρ i 2 ζ i i 2 γ i i ) x i 1 x i 2 2
(3.15)

and

F i ( T i 1 x 1 1 , , T i i 1 x i 1 1 , T i i x i 2 , T i i + 1 x i + 1 1 , , T i m x m 1 ) F i ( T i 1 x 1 2 , , T i i 1 x i 1 2 , T i i x i 2 , T i i + 1 x i + 1 2 , , T i m x m 2 ) ζ i 1 T i 1 x 1 1 T i 1 x 1 2 + + ζ i i 1 T i i 1 x i 1 1 T i i 1 x i 1 2 + ζ i i + 1 T i i + 1 x i + 1 1 T i i + 1 x i i + 1 2 + + ζ i m T i m x m 1 T i m x m 2 = j = 1 , j i m ζ i j T i j x j 1 T i j x j 2 j = 1 , j i m ζ i j γ i j x j 1 x j 2 .
(3.16)

From (3.13)-(3.16), we have

G ( x 1 1 , x 2 1 , , x m 1 ) G ( x 1 2 , x 2 2 , , x m 2 ) i = 1 m ( 1 2 δ i + ξ i 2 + τ i r i t i β i 2 ξ i 2 2 ρ i μ i δ i 2 + 2 ρ i c i ζ i i 2 γ i i 2 + ρ i 2 ζ i i 2 γ i i 2 ) x i 1 x i 2 + j = 1 , j i m ρ j τ j ζ i j γ i j r j t j x j 1 x j 2 = j = 1 m θ j x j 1 x j 2 θ j = 1 m x j 1 x j 1 = θ ( x 1 1 , x 2 1 , , x m 1 ) ( x 1 2 , x 2 2 , , x m 2 ) ,

where θ= max 1 j m θ j . It follows from assumption (3.5) that 0<θ<1. This shows that G: H 1 × H 2 ×× H m H 1 × H 2 ×× H m is a contractive operator, and so there exists a unique ( x 1 , x 2 ,, x m ) H 1 × H 2 ×× H m such that G( x 1 , x 2 ,, x m )=( x 1 , x 2 ,, x m ). Thus, ( x 1 , x 2 ,, x m ) is the unique solution of the problem (1.2).

Now we prove that x i n x i as n for i=1,2,,m. In fact, it follows from (3.4) and Lemma 2.2 that

x i n + 1 x x i n x i ( g i ( x i n ) g i ( x i ) ) + R M i , ρ i A i , η i [ A i ( g i ( x i n ) ) ρ i F i ( T i 1 x 1 n , , T i i 1 x i 1 n , T i i x i n , T i i + 1 x i + 1 n , , T i m x m n ) ] R M i , ρ i A i , η i [ A i ( g i ( x i ) ) ρ i F i ( T i 1 x 1 , , T i i 1 x i 1 , T i i x i , T i i + 1 x i + 1 , , T i m x m ) ] + w i n x i n x i ( g i ( x i n ) g i ( x i ) ) + w i n + τ i r i t i A i ( g i ( x i n ) ) A i ( g i ( x i ) ) ρ i [ F i ( T i 1 x 1 n , , T i i 1 x i 1 n , T i i x i n , T i i + 1 x i + 1 n , , T i m x m n ) F i ( T i 1 x 1 n , , T i i 1 x i 1 n , T i i x i , T i i + 1 x i + 1 n , , T i m x m n ) ] + τ i ρ i r i t i F i ( T i 1 x 1 n , , T i i 1 x i 1 n , T i i x i , T i i + 1 x i + 1 n , , T i m x m n ) F i ( T i 1 x 1 , , T i i 1 x i 1 , T i i x i , T i i + 1 x i + 1 , , T i m x m ) .
(3.17)

Following very similar arguments from (3.14)-(3.16), we have

x i n + 1 x i 1 2 δ i + ξ i 2 x i n x i + τ i r i t i [ β i 2 ξ i 2 2 ρ i μ i δ i 2 + 2 ρ i c i ζ i i 2 γ i i 2 + ρ i 2 ζ i i 2 γ i i 2 x i n x i + ρ i j = 1 , j i m ζ i j γ i j x j n x j ] + w i n ,
(3.18)

which implies that

j = 1 m x j n + 1 x j = j = 1 m θ j x j n x j + j = 1 m w j n θ j = 1 m x j n x j + j = 1 m w j n ,

where a n = j = 1 m x j n x j , b n = j = 1 m w j n . The condition of Algorithm 3.2 yields lim n b n =0. Now Lemma 2.4 implies that lim n a n =0, and so x j n x j as n for j=1,2,,m. This completes the proof. □

Remark 3.4 If m=2, g 1 = g 2 = U 11 = U 22 I (right now, δ i = ξ i = ζ i i =1 for i=1,2), then Theorem 3.1 reduces to Theorem 4.5 based on Algorithm 4.3 of Agarwal and Verma [34]. Our presented results improve and extend some known results in the literature.