Results 11 to 20 of about 84 (83)

Fuzzy approximation of an additive functional equation

Journal of Function Spaces, Volume 9, Issue 2, Page 205-215, 2011., 2011
In this paper, we investigate the generalized Hyers– Ulam– Rassias stability of the functional equation ∑i=1mf(mxi+∑j=1, j≠imxj)+f(∑i=1mxi)=2f(∑i=1mmxi) in fuzzy Banach spaces and some applications of our results in the stability of above mapping from a normed space to a Banach space will be exhibited.
G. Zamani Eskandani, Ali Reza Zamani, H. Vaezi, Nicolae Popa   +3 more
wiley   +1 more source

The Jensen functional equation in non‐Archimedean normed spaces

Journal of Function Spaces, Volume 7, Issue 1, Page 13-24, 2009., 2009
We investigate the Hyers–Ulam–Rassias stability of the Jensen functional equation in non‐Archimedean normed spaces and study its asymptotic behavior in two directions: bounded and unbounded Jensen differences. In particular, we show that a mapping f between non‐Archimedean spaces with f(0) = 0 is additive if and only if ‖f(x+y2)−f(x)+f(y)2‖→0 as max ...
Mohammad Sal Moslehian, George Isac
wiley   +1 more source

Local stability of the additive functional equation and its applications

International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 1, Page 15-26, 2003., 2003
The main purpose of this paper is to prove the Hyers‐Ulam stability of the additive functional equation for a large class of unbounded domains. Furthermore, by using the theorem, we prove the stability of Jensen′s functional equation for a large class of restricted domains.
Soon-Mo Jung, Byungbae Kim
wiley   +1 more source

Notes on stability of the generalized gamma functional equation

International Journal of Mathematics and Mathematical Sciences, Volume 32, Issue 1, Page 57-63, 2002., 2002
The Hyers‐Ulam stability in three senses is discussed by Kim (2001) for the generalized gamma functional equation g(x + p) = a(x)g(x) under some conditions which involve convergence of complicated series. In this note, those conditions are simplified to be checked easily and more interesting examples other than the classical gamma functional equation ...
Gwang Hui Kim, Bing Xu, Weinian Zhang
wiley   +1 more source

On the stability of the quadratic mapping in normed spaces

International Journal of Mathematics and Mathematical Sciences, Volume 25, Issue 4, Page 217-229, 2001., 2001
The Hyers‐Ulam stability, the Hyers‐Ulam‐Rassias stability, and also the stability in the spirit of Gavruţa for each of the following quadratic functional equations f(x + y) + f(x − y) = 2f(x) + 2f(y), f(x + y + z) + f(x − y) + f(y − z) + f(z − x) = 3f(x) + 3f(y) + 3f(z), f(x + y + z) + f(x) + f(y) + f(z) = f(x + y) + f(y + z) + f(z + x) are ...
Gwang Hui Kim
wiley   +1 more source

A functional equation characterizing cubic polynomials and its stability

International Journal of Mathematics and Mathematical Sciences, Volume 27, Issue 5, Page 301-307, 2001., 2001
We study the generalized Hyers‐Ulam stability of the functional equation f[x1, x2, x3] = h(x1 + x2 + x3).
Soon-Mo Jung, Prasanna K. Sahoo
wiley   +1 more source

On the stability of generalized gamma functional equation

International Journal of Mathematics and Mathematical Sciences, Volume 23, Issue 8, Page 513-520, 2000., 2000
We obtain the Hyers‐Ulam stability and modified Hyers‐Ulam stability for the equations of the form g(x + p) = φ(x)g(x) in the following settings: |g(x + p) − φ(x)g(x) | ≤ δ, | g(x + p) − φ(x)g(x) | ≤ ϕ(x), | (g(x + p)/φ(x)g(x)) − 1 | ≤ ψ(x). As a consequence we obtain the stability theorems for the gamma functional equation.
Gwang Hui Kim
wiley   +1 more source

Superstability of functional equations related to spherical functions

Open Mathematics, 2017
In this paper we prove stability-type theorems for functional equations related to spherical functions. Our proofs are based on superstability-type methods and on the method of invariant means.
Székelyhidi László
doaj   +1 more source

Enriched (f, ϕ, ψ, s)‐Functional Contractions and Stability of Nonlinear Volterra Integral and Fractional Differential Equations

Journal of Function Spaces, Volume 2026, Issue 1, 2026.
In this paper, we develop a comprehensive analytical framework for generalized nonlinear, nonhomogeneous Volterra integral equations and fractional differential equations in b‐metric spaces equipped with amorphous binary relations. By introducing an enriched (f, ϕ, ψ, s)‐functional contraction, we extend classical contractive conditions to accommodate ...
D. Srinivasan, D. Ramesh Kumar, Xinan Hao   +2 more
wiley   +1 more source

Pseudo almost periodic solutions for a class of differential equation with delays depending on state

Advances in Nonlinear Analysis, 2019
In this paper, the exponential dichotomy, and Tikhonov and Banach fixed point theorems are used to study the existence and uniqueness of pseudo almost periodic solutions of a class of iterative functional differential equations of the ...
Zhao Hou Yu
doaj   +1 more source