-solutions of a system of functional equations
A characterization of some classes of functions F which have a representation of the formF(x,y) = φ(h(x)+k(y))is given, when F is monotonic in each variable but not strictly monotonic. Some particular results concern classes of solutions of the bisymmetry or associativity equations.
There are many inequalities which in the class of continuous functions are equivalent to convexity (for example the Jensen inequality and the Hermite-Hadamard inequalities). We show that this is not a coincidence: every nontrivial linear inequality which is valid for all convex functions is valid only for convex functions.
Given a finite subset of , we study the continuous complex valued functions and the Schwartz complex valued distributions defined on with the property that the forward differences are (in distributional sense) continuous exponential polynomials for some natural numbers .
We give a characterization of the globally Lipschitzian composition operators acting in the space