Results 21 to 30 of about 89 (80)

Asymptotic behavior of Fréchet functional equation and some characterizations of inner product spaces

Demonstratio Mathematica, 2023
This article presents the general solution f:G→Vf:{\mathcal{G}}\to {\mathcal{V}} of the following functional equation: f(x)−4f(x+y)+6f(x+2y)−4f(x+3y)+f(x+4y)=0,x,y∈G,f\left(x)-4f\left(x+y)+6f\left(x+2y)-4f\left(x+3y)+f\left(x+4y)=0,\hspace{1.0em}x,y\in {\
Park Choonkil, Tareeghee Mohammad Amin, Najati Abbas, Yengejeh Yavar Khedmati, Paokanta Siriluk   +4 more
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A Functional equation related to inner product spaces in non-archimedean normed spaces

Advances in Difference Equations, 2011
In this paper, we prove the Hyers-Ulam stability of a functional equation related to inner product spaces in non-Archimedean normed spaces. 2010 Mathematics Subject Classification: Primary 46S10; 39B52; 47S10; 26E30; 12J25.
shin Dong, Park Choonkil, Gordji Madjid, Khodabakhsh Razieh, Khodaei Hamid   +4 more
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The new investigation of the stability of mixed type additive-quartic functional equations in non-Archimedean spaces

Demonstratio Mathematica, 2020
In this article, we prove the generalized Hyers-Ulam stability for the following additive-quartic functional equation:f(x+3y)+f(x−3y)+f(x+2y)+f(x−2y)+22f(x)+24f(y)=13[f(x+y)+f(x−y)]+12f(2y),f(x+3y)+f(x-3y)+f(x+2y)+f(x-2y)+22f(x)+24f(y)=13{[}f(x+y)+f(x-y)]
Thanyacharoen Anurak, Sintunavarat Wutiphol   +1 more
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Nonlinear approximation of an ACQ-functional equation in nan-spaces

Fixed Point Theory and Applications, 2011
In this paper, using the fixed point and direct methods, we prove the generalized Hyers-Ulam stability of an additive-cubic-quartic functional equation in NAN-spaces. Mathematics Subject Classification (2010) 39B52·47H10·26E30·46S10·
Lee Jung, Park Choonkil, Azadi Kenary Hassan   +2 more
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A Functional Equation with Biadditive Functions

Annales Mathematicae Silesianae, 2022
Let S, H, X be groups. For two given biadditive functions A : S2 → X, B : H2 → X and for two unknown mappings T : S → H, g : S → S we will study the functional ...
Łukasik Radosław
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Approximately cubic functional equations and cubic multipliers

Journal of Inequalities and Applications, 2011
In this paper, we prove the Hyers-Ulam stability and the superstability for cubic functional equation by using the fixed point alternative theorem. As a consequence, we show that the cubic multipliers are superstable under some conditions.
Alias Idham, Bodaghi Abasalt, Ghahramani Mohammad   +2 more
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Fuzzy stability of multi-additive mappings

Demonstratio Mathematica
The main aim of this study is to establish some stability results concerning the multi-additive mappings by applying the so-called direct (Hyers) method and the alternative fixed approach in the setting of fuzzy normed spaces.
Park Choonkil, Bodaghi Abasalt, Donganont Mana   +2 more
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Orthogonal Stability of an Additive-Quadratic Functional Equation

Fixed Point Theory and Applications, 2011
Using the fixed point method and using the direct method, we prove the Hyers-Ulam stability of an orthogonally additive-quadratic functional equation in orthogonality spaces. (2010) Mathematics Subject Classification: Primary 39B55; 47H10; 39B52; 46H25.
Park Choonkil
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Approximate *-derivations and approximate quadratic *-derivations on C*-algebras

Journal of Inequalities and Applications, 2011
In this paper, we prove the stability of *-derivations and of quadratic *-derivations on Banach *-algebras. We moreover prove the superstability of *-derivations and of quadratic *-derivations on C*-algebras.
Park Choonkil, Jang Sun
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Superstability of generalized cauchy functional equations

Advances in Difference Equations, 2011
In this paper, we consider the stability of generalized Cauchy functional equations such as Especially interesting is that such equations have the Hyers-Ulam stability or superstability whether g is identically one or not.
Chung Soon-Yeong, Lee Young-Su
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