Driss Zeglami

A variant of Wilson's functional equation

In the present paper we determine the complex-valued solutions (f, g) of the functional equation f(xy) + f(σ(y)x) = 2f(x)g(y), in the setting of groups and monoids that need not be abelian, where σ is an involutive automorphism.

On the stability of the generalized mixed trigonometric functional equations

Abstract In this paper, we will prove the superstability of the functional equation ∑ ϕ∈Φ ∫ K f(xkϕ(y)k -1 )dw K (k)=|Φ|f(x)g(y),x,y∈G,

Harmonic analysis and generalized functional equations for the cosine

\sum _{\varphi \in \Phi }\int _{K} f(xk\varphi (y)k^{-1})dw_{K}(k) =\vert \Phi \vert f(x)g(y), \quad x,y\in G,

D’Alembert’s Functional Equation and Superstability Problem in Hypergroups

which is bounded by the real functions φ(x)

A special class of functional equations

{\phi (x)}

A variant of Jensen’s functional equation on semigroups

, ψ(y)

Wilson’s type Hilbert space valued functional equations

{\psi (y)}

A joint generalization of Van Vleck's and Kannappan's equations on groups

or min(φ(x),ψ(y))

On the superstability of the pexider type generalized trigonometric functional equations

{\min (\phi (x),\psi (y))}

ON A COMPOSITE FUNCTIONAL EQUATION RELATED TO THE GOLAB-SCHINZEL EQUATION

, where f, g are unknown continuous complex-valued functions. Here G is any topological group, K is a compact subgroup of G, ω K