FUNCTIONAL INEQUALITIES IN FUZZY NORMED SPACES

초록

In this paper, we solve the following (additive functional inequality N(f(x + y) - f(x) - f(y), t) >= N(f(x + y/2) - 1/2 f(x) - f(y), t) (0.1) and the following quadratic functional inequality N(f (x + y) + f (x - y) - 2f (x) - 2f (y), t) (0.2) >= N (2f (x + y/2) + 2f (x - y/2) - f (y), t) in fuzzy normed spaces. Using the fixed point method, we prove the Hyers-Ulam stability of the additive functional inequality (0.1) and the quadratic functional inequality (0.2) in fuzzy Banach spaces.

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