A covering theorem for set-valued mappings

The notion of covering is introduced for a set-valued mapping defined on an arbitrary set in a Banach space. A necessary and sufficient covering criterion is proved. The conditions are formulated in terms of generalized differentials and generalized normals. The covering theorem is applied to deduce formulas of generalized differential calculus and necessary optimality conditions for nonsroooth optimization problems.     

A Sard theorem for tame set-valued mappings

If F is a set-valued mapping from Rn into Rm with closed graph, then y∈Rm is a critical value of F if for some x with y∈F(x), F is not metrically regular at (x,y). We prove that the set of critical values of a set-valued mapping whose graph is a definable (tame) set in an o-minimal structure containing additions and multiplications is a set of dimension not greater than m−1 (respectively a σ-porous set). As a corollary of this result we get that the collection of asymptotically critical values of a set-valued mapping with a semialgebraic graph has dimension not greater than m−1. We also give an independent proof of the fact that a definable continuous real-valued function is constant on components of the set of its subdifferentiably critical points.     

Turnpike theorem for a class of set-valued mappings

In this work we study the asymptotic behavior of optimal trajectories for a class of superlinear mappings arising in economic dynamics. We establish the existence of an open everywhere dense subset F of the space of set-valued mappings such that each mapping fron F has the turnpike property.     

Coincidence theorem for admissible set-valued mappings and its applications in FC-spaces

A new coincidence theorem for admissible set-valued mappings is proved in FC-spaces with a more general convexity structure. As applications, an abstract variational inequality, a KKM type theorem and a fixed point theorem are obtained. Our results generalize and improve the corresponding results in the literature.     

An intersection theorem for supermatroids

We generalize the matroid intersection theorem to distributive supermatroids, a structure that extends the matroid to the partially ordered ground set. Distributive supermatroids are special cases of both supermatroids and greedoids, and they generalize polymatroids. This is the first good characterization proved for the intersection problem of an independence system where the ground set is partially ordered. The characterization given has a more complex structure than the matroid (or polymatroid) intersection theorem.     

An invariance theorem for mappings

If a continuous mapping f carries the boundary of a set D into the closure of D, it may not be true that f maps D into its closure, even if f is injective on D. Examples are discussed, and conditions are given under which it is true. A simplified application is given to a biological migration–selection model.     

An intersection theorem for four sets

Fix integers n,r?4 and let F denote a family of r-sets of an n-element set. Suppose that for every four distinct A,B,C,D∈F with |A∪B∪C∪D|?2r, we have A∩B∩C∩D≠∅. We prove that for n sufficiently large, , with equality only if _?F∈FF≠∅. This is closely related to a problem of Katona and a result of Frankl and Füredi [P. Frankl, Z. Füredi, A new generalization of the Erd?s-Ko-Rado theorem, Combinatorica 3 (3-4) (1983) 341-349], who proved a similar statement for three sets. It has been conjectured by the author [D. Mubayi, Erd?s-Ko-Rado for three sets, J. Combin. Theory Ser. A, 113 (3) (2006) 547-550] that the same result holds for d sets (instead of just four), where d?r, and for all n?dr/(d−1). This exact result is obtained by first proving a stability result, namely that if |F| is close to then F is close to satisfying _?F∈FF≠∅. The stability theorem is analogous to, and motivated by the fundamental result of Erd?s and Simonovits for graphs.     

An intersection theorem for multivalued maps

LetE be a Banach space and letV, W ? E be two closed subspaces such thatE=V ⊕ W. LetF, G: E-· E be two multivalued maps. The problem we are concerned with is to give conditions onF andG ensuring the nonemptiness ofF(V) ∩ G(W).     

Minimax inequalities for set-valued mappings

In this paper, by using the finite intersection property, we first obtain two types of minimax inequalities for set-valued mappings, which improve and generalize the corresponding results in Ferro (J Optim Theory Appl 60:19?C31, 1989) and Li et?al. (J Math Anal Appl 281:707?C723, 2003). Then, by using the Ky Fan lemma and the Kakutani?CFan?CGlicksberg fixed point theorem, we also investigate some Ky Fan minimx inequalities for set-valued mappings.     

Ekeland's variational principle and Caristi's coincidence theorem for set-valued mappings in probabilistic metric spaces

By using the partial ordering method, a more general type of Ekeland's variational principle and Caristi's coincidence theorem for set-valued mappings in probabilistic metric spaces are given in this paper. In addition, we give also a directly simple proof of the equivalence between theses theorems in probabilistic metric spaces.This paper was supported financially from the National Natural Science Foundation of China, 1994, and the Basic Science Research Institute Program, Ministry of Education, Korea, 1995, Project No. BSRI-95-1405.     

Real-valued Choquet integrals for set-valued mappings

In this paper a new kind of real-valued Choquet integrals for set-valued mappings is introduced, and some elementary properties of this kind of Choquet integrals are studied. Convergence theorems of a sequence of Choquet integrals for set-valued mappings are shown. However, in the case of the monotone convergence theorem of the nonincreasing sequence of Choquet integrals for set-valued mappings, we point out that the integrands must be closed. Specially, this kind of real-valued Choquet integrals for set-valued mappings can be regarded as the Choquet integrals for single-valued functions.     

Vector variational-type inequalities for set-valued mappings

In this paper, we consider the existence of solutions to the vector variational-type inequalities for set-valued mappings on Hausdorff topological vector spaces using Fan's geometrical lemma.     

General hyperbolicity conditions for set-valued mappings

A definition of hyperbolicity for dynamical systems generated by set-valued mappings of general form in terms of local selectors is given. It is shown that a system hyperbolic in this sense has the shadowing and inverse shadowing properties. It is also shown that the hyperbolicity property holds true for a certain class of set-valued mappings where images of points are convex polytopes. Bibliography: 13 titles.     

Generalized minimax inequalities for set-valued mappings

In this paper, we study generalized minimax inequalities in a Hausdorff topological vector space, in which the minimization and the maximization of a two-variable set-valued mapping are alternatively taken in the sense of vector optimization. We establish two types of minimax inequalities by employing a nonlinear scalarization function and its strict monotonicity property. Our results are obtained under weaker convexity assumptions than those existing in the literature. Several examples are given to illustrate our results.     

对Aubin与Frankowska关于闭凸集值映射最小选择的一个结果的讨论

本文对J.-P.Aubin与H.Frankowska最近关于自反严格凸Banach空间中闭凸集值映射最小选择连续的一个结果加以讨论,首先在比自反性较强的一类空间中讨论了在弱于J.-P.Aubin与H.Frankowska的条件下闭凸集值映射最小选择的连续性,其次对J.-P.Aubin与H.Frankowska的结果给出一个新的简单证明,最后用反例说明本文给出的条件与J.-P.Aubin与H.Frankowska条件都是充分而不必要的.     

On pseudomonotone set-valued mappings

In this paper a common generalization of the algebraic and topological pseudomonotonicity for set-valued maps is introduced. Existence results for variational inequalities governed by such maps are given.     

An inverse mapping theorem for H-differentiable set-valued maps

Taking advantage of recent developments in the theory of generalized differentiation, we present an inverse mapping theorem for set-valued maps and prove its stability under small linear perturbations. Using variational convergences of set-valued mappings, we present as well an approximate version of our inverse theorem.     

On some extension theorems for set-valued mappings

In this short note we give counterexamples to several results related to extension theorems published recently.