Mathematical Inequalities & Applications · Volume 13, Issue 3 Functional characterization of a sharpening of the triangle inequality 13-39 Pages 571-578 DOI 10.7153/mia-13-39 Downloads Short PDF Full PDF PNG Authors Włodzimierz Fechner Keywords norm inequality triangle inequality functional equation functional inequality Hyers-Ulam stability Subject classes 39B62 39B82 46B20 46B99