Stability of functional equations in several variables

the long version

The notion of stability of functional equations has its origins with S. M. Ulam, who posed the fundamental problem in 1940 and with D. H. Hyers, who gave the first significant partial solution in 1941. During the last two decades the notion of stability of functional equations has evolved into an area of continuing research. The present book is a comprehensive introduction to the subject with emphasis on recent developments. The authors present both the classical results and current research in a unified and self-contained fashion. In addition, related problems are investigated. These include the stability of the convex functional inequality and the stability of minimum points. The work is certainly of interest to researchers in the field. And since the techniques used here require only basic knowledge of functional analysis, algebra, and topology, the work is therefore accessible to graduate students as well.