. The theory of difference equations, the methods used in their
solutions and their wide applications have advanced beyond their
adolescent stage to occupy a central position in Applicable Analysis. In
fact, in the last five years, the proliferation of the subject is
witnessed by hundreds of research articles and several monographs, two
International Conferences and numerous Special Sessions, and a new
Journal as well as several special issues of existing journals, all
devoted to the theme of Difference Equations. Now even those experts who
believe in the universality of differential equations are discovering
the sometimes striking divergence between the continuous and the
discrete. There is no doubt that the theory of difference equations will
continue to play an important role in mathematics as a whole. In 1992,
the first author published a monograph on the subject entitled
Difference Equations and Inequalities. This book was an in-depth survey
of the field up to the year of publication. Since then, the subject has
grown to such an extent that it is now quite impossible for a similar
survey, even to cover just the results obtained in the last four years,
to be written. In the present monograph, we have collected some of the
results which we have obtained in the last few years, as well as some
yet unpublished ones.