We consider a new approach to approximate stability analysis for a tri-additive functional
inequality and to obtain the optimal approximation for permuting tri-derivations and tri …

Ulam stability is motivated by the following issue: how much an approximate solution of an
equation differs from the exact solutions to the equation. It is connected to some other areas …

We prove a fixed point theorem for function spaces, that is a very efficient and convenient
tool for the investigations of various operator inequalities connected to Ulam stability issues …

The theory of Ulam stability was initiated by a problem raised in 1940 by S. Ulam and
concerning approximate solutions to the equation of homomorphism in groups. It is …

The Ulam stability concerns the following issue: how much an approximate solution to an
equation differs from an exact solution to the equation. We prove a general Ulam stability …

The problem of Ulam stability for equations can be stated in terms of how much the
mappings satisfying the equations approximately (in a sense) differ from the exact solutions …

We suggest a somewhat new approach to the issue of Hyers–Ulam stability. Namely, let A, B
be (real or complex) linear spaces, L: A→ B be a linear operator, N:= ker L, and ρ A and ρ B …

Using a fixed point result and an approach to stability of functional equations presented in 8,
we investigate a new type of stability for the radical quadratic functional equation of the form …

The aim of this paper is first to reformulate the fixed point theorem [4, Theorem 1] in 2-
Banach spaces, after it, we introduce and solve the radical quartic functional equation f (x 4+ …

The aim of this research is first to introduce and solve a certain class of generalized multi-
Drygas equations. Under suitable assumptions, we prove an interesting result concerning …