On the superstability of generalized d'Alembert harmonic functions

Iz-iddine EL-Fassi

Abstract


The aim of this paper is to study the superstability problem of the d'Alembert type functional equation

f(x+y+z)+f(x+y+σ(z))+f(x+σ(y)+z)+f(σ(x)+y+z)=4f(x)f(y)f(z)

for all x,y,z ∈ G, where G is an abelian group and σ: G → G is an endomorphism such that σ(σ(x))=x for an unknown function f from G into C or into a commutative semisimple Banach algebra.

Keywords


stability, d’Alembert functional equation

Mathematics Subject Classification (2010)


39B82; 39B52

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