Functional analysis
1. A new type of Hyers-Ulam-Rassias stability for Drygas functional equation

M. Sirouni; M. ‎Almahalebi; S. ‎Kabbaj

Volume 07, Issue 04 , Autumn 2018, , Pages 251-260

Abstract
  In this paper, we prove the generalized Hyers-Ulam-Rassias stability for the Drygas functional equation$$f(x+y)+f(x-y)=2f(x)+f(y)+f(-y)$$ in Banach spaces by using the Brz\c{d}ek's fixed point theorem. Moreover, we give a general result on the hyperstability of this equation. Our results are improvements ...  Read More