Generalized functional inequalities in Banach spaces

Abstract

In this paper, we solve and investigate the generalized additive functional inequalities ‖F(∑i=1nxi)-∑i=1nF(xi)‖≤‖F(1n∑i=1nxi)-1n∑i=1nF(xi)‖\left\| {F\left( {\sum\limits_{i = 1}^n {{x_i}} } \right) - \sum\limits_{i = 1}^n {F\left( {{x_i}} \right)} } \right\| \le \left\| {F\left( {{1 \over n}\sum\limits_{i = 1}^n {{x_i}} } \right) - {1 \over n}\sum\limits_{i = 1}^n {F\left( {{x_i}} \right)} } \right\| and ‖F(1n∑i=1nxi)-1n∑i=1nF(xi)‖≤‖F(∑i=1nxi)-∑i=1nF(xi)‖.\left\| {F\left( {{1 \over n}\sum\limits_{i = 1}^n {{x_i}} } \right) - {1 \over n}\sum\limits_{i = 1}^n {F\left( {{x_i}} \right)} } \right\| \le \left\| {F\left( {\sum\limits_{i = 1}^n {{x_i}} } \right) - \sum\limits_{i = 1}^n {F\left( {{x_i}} \right)} } \right\|.

Keywords

• hyers-ulam stability
• non-archimedean normed space
• functional inequality
• banach space
• cauchy functional equation
• primary: 46s10, 39b62, 39b52
• secondary: 47h10, 47s10, 12j25