English

Stability of a functional equation of Deeba on semigroups

Classical Analysis and ODEs 2007-07-06 v1 Functional Analysis

Abstract

Let SS be a semigroup and XX a Banach space. The functional equation ϕ(xyz)+ϕ(x)+ϕ(y)+ϕ(z)=ϕ(xy)+ϕ(yz)+ϕ(xz)\phi (xyz)+ \phi (x) + \phi (y) + \phi (z) = \phi (xy) + \phi (yz) + \phi (xz) is said to be stable for the pair (X,S)(X, S) if and only if f:SXf: S\to X satisfying f(xyz)+f(x)+f(y)+f(z)f(xy)f(yz)f(xz)δ\| f(xyz)+f(x) + f(y) + f(z) - f(xy)- f(yz)-f(xz)\| \leq \delta for some positive real number δ\delta and all x,y,zSx, y, z \in S, there is a solution ϕ:SX\phi : S \to X such that fϕf-\phi is bounded. In this paper, among others, we prove the following results: 1) this functional equation, in general, is not stable on an arbitrary semigroup; 2) this equation is stable on periodic semigroups; 3) this equation is stable on abelian semigroups; 4) any semigroup with left (or right) law of reduction can be embedded into a semigroup with left (or right) law of reduction where this equation is stable.

Keywords

Cite

@article{arxiv.0707.0795,
  title  = {Stability of a functional equation of Deeba on semigroups},
  author = {Valeriy A. Faiziev and Prasanna K. Sahoo},
  journal= {arXiv preprint arXiv:0707.0795},
  year   = {2007}
}

Comments

29 pages

R2 v1 2026-06-21T08:55:28.720Z