EN
Introduction
The main result of this paper is concerned with the conditions which guarantee that a multifunction $f: C → 2^X$ defined on an arbitrary subset C of a topological vector space X admits a point x of C such that x∈f(x).
First, we give some definitions and propositions which are associated with semicontinuous multifunctions (Part 1).
Next, in Part 2, we present a global convergence criterion on variable dimension algorithms for finding an approximate solution of the equation x∈f(x), and then we consider some fixed point theorems for multifunctions defined in finite-dimensional spaces.
Part 3 contains fixed point theorems for quasi upper semicontinuous multifunctions defined on arbitrary domains of topological vector spaces which generalize the theorems with boundary conditions.
Part 4 is devoted to some fixed point theorems for strongly lower semicontinuous multifunctions and thus here we are first concerned with fixed point theorems under boundary conditions for this class of multi-functions.
The last part shows how we can apply the results obtained to existence problem of equilibrium situations in the theory of non-cooperative games.
CONTENTS
Introduction..........................................................................................................5
1. Some classes of semicontinuous multifunctions...............................................5
2. A remark on the convergence of variable dimension algorithms.......................9
3. Some fixed point theorems.............................................................................15
4. Fixed point theorems for strongly lower semicontinuous multifunctions..........24
5. Some applications in game theory..................................................................29
References.........................................................................................................34