Stability of a functional inequality associated with the Jordan-von Neumann functional equation. (English) Zbl 1098.39019
The Hyers-Ulam stability of the functional inequality
\[
\| 2 f(x)+2f(y)-f(x-y)\| \leq \| f(x+y)\| ,\quad (\text{for all }x,y)
\]
is investigated in the spirit of P. Găvruţă’s paper [J. Math. Anal. Appl. 184, 431–436 (1994; Zbl 0818.46043)].
Reviewer: Paşc Găvruţă (Timişoara)
MSC:
| 39B82 | Stability, separation, extension, and related topics for functional equations |
| 39B52 | Functional equations for functions with more general domains and/or ranges |
| 39B62 | Functional inequalities, including subadditivity, convexity, etc. |
