Functional Inequalities Associated with Additive Mappings
نویسندگان
چکیده
The functional inequality ‖f x 2f y 2f z ‖ ≤ ‖2f x/2 y z ‖ φ x, y, z x, y, z ∈ G is investigated, where G is a group divisible by 2, f : G→ X and φ : G3 → 0,∞ are mappings, and X is a Banach space. The main result of the paper states that the assumptions above together with 1 φ 2x,−x, 0 0 φ 0, x,−x x ∈ G and 2 limn→∞ 1/2 φ 2 1x, 2y, 2z 0, or limn→∞2φ x/2n−1, y/2, z/2 0 x, y, z ∈ G , imply that f is additive. In addition, some stability theorems are proved.
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تاریخ انتشار 2008