Math. Meth. Oper. Res. (2006) 63: 553–565
DOI 10.1007/s00186-005-0052-2
ORIGINAL ARTICLE
E. Allevi · A. Gnudi · I. V. Konnov
The proximal point method
for nonmonotone variational inequalities
Received: 15 July 2004 / Accepted: 15 April 2005 / Published online: 29 June 2006
© Springer-Verlag 2006
Abstract We consider an application of the proximal point method to variational
inequality problems subject to box constraints, whose cost mappings possess order
monotonicity properties instead of the usual monotonicity ones. Usually, conver-
gence results of such methods require the additional boundedness assumption of
the solutions set. We suggest another approach to obtaining convergence results
for proximal point methods which is based on the assumption that the dual varia-
tional inequality is solvable. Then the solutions set may be unbounded. We present
classes of economic equilibrium problems which satisfy such assumptions.
Keywords Proximal point method · Multivalued variational inequalities ·
Box-constrained sets · Nonmonotone mappings
1 Introduction
Let X be a nonempty convex set in the real n-dimensional space R
n
, and let
G : X → (R
n
) be a multivalued mapping [Here and below (A) denotes the
family of all nonempty subsets of a set A]. Then one can define the multivalued
variational inequality problem (VI for short): Find a point x
∗
∈ X such that
E. Allevi
Department of Quantitative Methods, Brescia University, Contrada Santa Chiara,
50, Brescia 25122, Italy
A. Gnudi
Department of Mathematics, Statistics, Informatics and Applications,
Bergamo University,Via dei Caniana, 2, Bergamo 24127, Italy
I. V. Konnov (B )
Department of Applied Mathematics, Kazan University,
ul. Kremlevskaya,18, Kazan 420008, Russia
E-mail: Igor.konnov@ksu.ru