1. ADDITIVE (ρ1, ρ2)-FUNCTIONAL INEQUALITIES IN COMPLEX BANACH SPACES.
- Author
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CHOONKIL PARK, DONG YUN SHIN, and ANASTASSIOU, GEORGE A.
- Subjects
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MATHEMATICAL inequalities , *BANACH spaces , *COMPLEX numbers , *FUNCTIONAL equations , *MATHEMATICAL analysis , *MATHEMATICAL functions - Abstract
In this paper, we introduce and solve the following additive (ρ1, ρ2)-functional in-equalities (0.1) ∥f (x + y + z) - f(x) - f(y) - f(z)∥ ≥ ∥ρ1(f(x + y - z) - f(x) - f(y) + f(z))∥ + ∥ρ2 (f(x - y + z) - f(x) + f(y) - f(z))∥, where ρ1 and ρ2 are fixed complex numbers with |ρ1| ⋅ |ρ2| > 1, and (0.2) ∥f (x + y - z) - f(x) - f(y) + f(z)∥ ≥ ∥ρ1(f(x + y + z) - f(x) - f(y) f(z))∥ + ∥ρ2 (f(x - y + z) - f(x) + f(y) f(z))∥ where ρ1 and ρ2 are fixed complex numbers with |ρ1| > 1. Using the fixed point method and the direct method, we prove the Hyers-Ulam stability of the additive (ρ1, ρ2)-functional inequalities (0.1) and (0.2) in complex Banach spaces. [ABSTRACT FROM AUTHOR]
- Published
- 2019