Hyers-Ulam Stability of Quadratic Operators in Locally Convex Cones

Abstract

The stability problem in Ulam's sense has recently been explored in locally convex cone environments, as shown in \cite{ MNF, NR1, NR2}. In continuation of this research direction, our work examines the stability properties of the quadratic functional equation \[ 2f\left(\frac{x+y}{2}\right) + 2f\left(\frac{x-y}{2}\right) = f(x) + f(y) \] in such structures. We present novel stability theorems that offer enhanced comprehension of operator behavior when subjected to perturbations. These results advance the theoretical framework of Hyers-Ulam stability within locally convex cones while elucidating distinctive characteristics of quadratic operators in this context. Our investigation both strengthens the mathematical underpinnings of stability theory and provides new perspectives on interactions between certain operators and locally convex spaces.