This book outlines the modern theory of functional equations and inequalities in several
variables. It consists of three parts. The first is devoted to additive and convex functions …

On several occasions in investigations of functional equations it has been observed that the
family of the solutions of the equation in question depends quite essentially on the domain in …

-Les proportions d'Eudoxe, la méthode d'exhaust-Un style pour penser les relations
fonctionnelles 2. Fonctions linéaires et affines: une caractérisat-N. Oresme et le théorème de …

Let (G,+, Σ, μ) be an abelian complete measurable group with μ (G)<+ ∞ and let E be a
Banach space. For any f: G → E we define the quadratic difference operator Qf by Qf (x, y) …

On approximate group homomorphisms - ScienceDirect Skip to main contentSkip to article
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The Olkin–Baker functional equation, except of being studied inside the theory of functional
equations, is closely related to the celebrated Lukacs characterization of the gamma …

For inner product spaces X and Y, we consider the orthogonality equation (f (x)| f (z))=(x| z)
for x, z∈ X as well as its restricted versions (f (x)| f (z))=(x| z) for (x, z)∈ X2\M and (f (x)| f …

Let (X, μ) be an abelian complete measurable group with μ(X)=+∞, and let E be a metric
abelian group. Let f:X→E be a function. We will show that if Qf∈L_p^+(X*X,E), where¶¶ …

To make it less abstract, answering the title question let us twist British mountaineer George
Mallory's famous dictum:“Because they're there.” The article yields a counterpart of Mihály …

Let X be an Abelian group, Y be a commutative monoid, K⊂ Y be a submonoid and F: X→
2Y\{∅} be a set-valued map. Under some additional assumptions on ideals I1 in X and I2 in …