On Hecke's functional equation

On Hilbert Golab-Schinzel type functional equation

Let $X$ be a vector space over a field $K$ of real or complex numbers. We will prove the superstability of the following Go{l}c{a}b-Schinzel type equation$$f(x+g(x)y)=f(x)f(y), x,yin X,$$where $f,g:Xrightarrow K$ are unknown functions (satisfying some assumptions). Then we generalize the superstability result for this equation with values in the field of complex numbers to the case of an arbitr...

Stability of additive functional equation on discrete quantum semigroups

We construct  a noncommutative analog of additive functional equations on discrete quantum semigroups and show that this noncommutative functional equation has Hyers-Ulam stability on amenable discrete quantum semigroups. The discrete quantum semigroups that we consider in this paper are in the sense of van Daele, and the amenability is in the sense of Bèdos-Murphy-Tuset. Our main result genera...

On the Stability of the Orthogonally Quartic Functional Equation

on hilbert golab-schinzel type functional equation

abstract. let x be a vector space over a field k of real or complex numbers.we will prove the superstability of the following golab-schinzel type equationf(x + g(x)y) = f(x)f(y); x; y 2 x;where f; g are unknown functions (satisfying some assumptions). then we generalize the superstability result for this equation with values in the field of complex numbers to the case of an arbitrary hilbert spac...

On the associativity functional equation

Let [a, b] be any bounded closed real interval. The class of all continuous, nondecreasing, associative functions M : [a, b] → [a, b] fulfilling the boundary conditions M(a, a) = a and M(b, b) = b is described.