On Hadamard integral inequalities involving two log-preinvex functions.
On measurable solutions of a functional equation and its application to information theory
On subaddidive and Ψ-additive mappings
On subadditive functions and ψ-additive mappings
In [4], assuming among others subadditivity and submultiplicavity of a function ψ: [0, ∞)→[0, ∞), the authors proved a Hyers-Ulam type stability theorem for “ψ-additive” mappings of a normed space into a normed space. In this note we show that the assumed conditions of the function ψ imply that ψ=0 and, consequently, every “ψ-additive” mapping must be additive
On the Cauchy functional inequality in Banach modules.
On the characterization of quasiarithmetic means with weight function.
On the continuity of Q-convex functions and additive functions.
On the continuity of Q-convex functions and additive functions. (Short Communication).
On the dominance relation between ordinal sums of conjunctors
This contribution deals with the dominance relation on the class of conjunctors, containing as particular cases the subclasses of quasi-copulas, copulas and t-norms. The main results pertain to the summand-wise nature of the dominance relation, when applied to ordinal sum conjunctors, and to the relationship between the idempotent elements of two conjunctors involved in a dominance relationship. The results are illustrated on some well-known parametric families of t-norms and copulas.
On the functional equation f(...(x) + g(y)) = ..(x) * h(x+y). (Short Communication).
On the functional equation f(...(x) + g(y)) = ...(x) * h(x+y).
On the general solution of a system of functional equations.
On the inverse stability of functional equations
The inverse stability of functional equations is considered, i.e. when the function, approximating a solution of the equation, is an approximate solution of this equation.
On the Normal Stability of Functional Equations
In the paper two types of stability and of b-stability of functional equations are distinguished.
On the radius of convergence of series solutions of a functional equation
On the second part of Hilbert's fifth problem.
On the stability of generalized additive functional inequalities in Banach spaces.
On the Stability of Orthogonal Additivity
We deal with the stability of the orthogonal additivity equation, presenting a new approach to the proof of a 1995 result of R, Ger and the second author. We sharpen the estimate obtained there. Moreover, we work in more general settings, providing an axiomatic framework which covers much more cases than considered before by other authors.
On the stability of the squares of some functional equations
We consider the stability, the superstability and the inverse stability of the functional equations with squares of Cauchy’s, of Jensen’s and of isometry equations and the stability in Ulam-Hyers sense of the alternation of functional equations and of the equation of isometry.
On the stabiltiy of a system of functional equations characterizing generalize hyperbolic and trigonometric functions.