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Additive (ρ1, ρ2)-Functional Inequalities in Complex Banach Spaces

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Computational Mathematics and Variational Analysis

Part of the book series: Springer Optimization and Its Applications ((SOIA,volume 159))

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Abstract

In this paper, we introduce and solve the following additive (ρ 1, ρ 2)-functional inequalities:

$$\displaystyle \begin{aligned} \begin{array}{rcl} \left\|f\left(x-y\right) - f(x )+ f(y)\right\| &\displaystyle \ge &\displaystyle \|\rho_1 (f(x+y)-f(x)-f(y))\| \\ &\displaystyle + &\displaystyle \left\|\rho_2 \left( f(y-x)-f(y)+f(x)\right)\right\|, {} \end{array} \end{aligned} $$
(1)

where ρ 1 and ρ 2 are fixed complex numbers with |ρ 1| + |ρ 2| > 1, and

$$\displaystyle \begin{aligned} \begin{array}{rcl} \left\|f\left(x+y\right) - f(x )- f(y)\right\|&\displaystyle \ge &\displaystyle \|\rho_1 (f(x-y)-f(x)+f(y))\| \\ &\displaystyle + &\displaystyle \left\|\rho_2 \left( f(y-x)-f(y)+f(x)\right)\right\| ,{} \end{array} \end{aligned} $$
(2)

where ρ 1 and ρ 2 are fixed complex numbers with 1 + |ρ 1| > |ρ 2| > 1. Using the fixed point method and the direct method, we prove the Hyers–Ulam stability of the additive (ρ 1, ρ 2)-functional inequalities (2) and (1) in complex Banach spaces.

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Acknowledgements

C. Park was supported by Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (NRF-2017R1D1A1B04032937).

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Correspondence to Themistocles M. Rassias .

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Lee, J.R., Park, C., Rassias, T.M. (2020). Additive (ρ1, ρ2)-Functional Inequalities in Complex Banach Spaces. In: Daras, N., Rassias, T. (eds) Computational Mathematics and Variational Analysis. Springer Optimization and Its Applications, vol 159. Springer, Cham. https://doi.org/10.1007/978-3-030-44625-3_13

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