Hyers-Ulam-Rassias Stability of Generalized Derivations

Approximation of a Cauchy-Jensen additive mapping in various normed spaces

In this paper, using the fixed point and direct methods, we prove the generalized Hyers-Ulam-Rassias stability of a Cauchy-Jensen additive functional equation in various normed spaces. The concept of Hyers-Ulam-Rassias stability originated from Th. M. Rassias stability theorem that appeared in his paper: On the stability of the linear mapping in Banach spaces, Proc. Amer. Math. Soc. 72 (1978), 297-300.

On coupled best proximity points and Ulam-Hyers stability

For two nonempty, closed, bounded and convex subsets $A$ and $B$ of a uniformly convex Banach space $X$ consider a mapping $T:(A \times B) \cup (B \times A) \rightarrow A \cup B$ satisfying $T(A,B) \subset B$ and $T(B, A) \subset A$. In this paper the existence of a coupled best proximity point is established when $T$ is considered to be a p-cyclic contraction mapping and a p-cyclic nonexpansive mapping. The Ulam-Hyers stability of the best proximity point problem is also studied.

局部凸锥中Pexiderized Cauchy函数方程的Hyers-Ulam型稳定性

Hyers-Ulam Type Stability of the Pexiderized Cauchy Functional Equation in Locally Convex Cones

本文在局部凸锥的三种拓扑框架下研究Pexiderized Cauchy函数方程的Hyers-Ulam型稳定性，并给出若干重要推论。

Hyers-Ulam Stability of Bessel Equations

We analyse different kinds of stabilities for the Bessel equation and for the modified Bessel equation with initial conditions. Sufficient conditions are obtained in order to guarantee Hyers-Ulam-Rassias, $σ$-semi-Hyers-Ulam and Hyers-Ulam stabilities for those equations. Those sufficient conditions are obtained based on the use of integral techniques and majorations.

Relationship between the Hyers-Ulam stability and the Moore-Penrose inverse

In this paper, we establish a link between the Hyers-Ulam stability and the Moore--Penrose inverse, that is, a closed operator has the Hyers-Ulam stability if and only if it has a bounded Moore-Penrose inverse. Meanwhile, the stability constant can be determined in terms of the Moore-Penrose inverse. Based on this result, some conditions for the perturbed operators having the Hyers--Ulam stability are obtained and the Hyers-Ulam stability constant is expressed explicitly in the case of closed operators. In the case of the bounded linear operators we obtain some characterizations for the Hyers-…

局部凸锥中二次算子的Hyers-Ulam稳定性

Hyers-Ulam Stability of Quadratic Operators in Locally Convex Cones

本文在局部凸锥框架下研究二次泛函方程的Hyers-Ulam稳定性，提出新的稳定性定理，深化了对二次算子受扰动时行为的理解，并推进了局部凸锥中稳定性理论的发展。

Uniqueness and Ulam-Hyers-Mittag-Leffler stability results for the delayed fractional multi-terms differential equation involving the $Φ$--Caputo fractional Derivative

The principal aim of the present paper is to establish the uniqueness and Ulam-Hyers Mittag-Leffler (UHML) stability of solutions for a new class of multi-terms fractional time-delay differential equations in the context of the $Φ$-Caputo fractional derivative. To achieve this purpose, the generalized Laplace transform method alongside facet with properties of the Mittag-Leffler functions (M-LFs), are utilized to give a new representation formula of the solutions for the aforementioned problem. Besides that, the uniqueness of the solutions of the considered problem is also proved by applying t…

Hilbert C*-模上同态与*-同态的Hyers-Ulam稳定性

Hyers-Ulam stability of homomorphisms and *-homomorphisms on Hilbert C*-modules

该研究提出Hilbert C*-模上*-同态的概念，并采用不动点方法证明了此类模上同态与*-同态的Hyers-Ulam稳定性。

Hyers-Ulam stability of the spherical functions

In \cite{bbb} the authors obtained the Hyers-Ulam stability of the functional equation $$ \int_{K}\int_{G} f(xtk\cdot y)dμ(t)dk=f(x)g(y), \; x, y \in G ,$$ where $G$ is a Hausdorff locally compact topological group, $K$ is a copmact subgroup of morphisms of $G$, $μ$ is a $K$-invariant complex measure with compact support, provided that the continuous function $f$ satisfies some Kannappan Type condition. The purpose of this paper is to remove this restriction.

Extremal Approximately Convex Functions and the Best Constants in a Theorem of Hyers and Ulam

Let $n\ge1$ and $B\ge2$. A real-valued function $f$ defined on the $n$-simplex $Δ_n$ is approximately convex with respect to $Δ_{B-1}$ iff f(\sum_{i=1}^B t_ix_i) \le \sum_{i=1}^B t_if(x_i) +1 for all $x_1,...,x_B \in Δ_n$ and all $(t_1,...,t_B)\in Δ_{B-1}$. We determine explicitly the extremal (i.e. pointwise largest) function of this type which vanishes on the vertices of $Δ_n$. We also prove a stability theorem of Hyers-Ulam type which yields as a special case the best constants in the Hyers-Ulam stability theorem for $ε$-convex functions.

Fuzzy stability of ring homomorphisms and ring derivations on fuzzy Banach algebras

In this paper, we establish the Hyers--Ulam--Rassias stability of ring homomorphisms and ring derivations on fuzzy Banach algebras.

Fixed points and the stability of the linear functional equations in a single variable

We prove that an interesting result concerning generalized Hyers-Ulam-Rassias stability of a linear functional equation obtained in 2014 by S.M. Jung, D. Popa and M.T. Rassias in Journal of Global Optimization is a particular case of a fixed point theorem given by us in 2012. Moreover, we give a characterization of functions that can be approximated with a given error, by the solution of the previously mention linear equation.

Stability of a functional equation deriving from quartic and additive functions

In this paper, we obtain the general solution and the generalized Hyers-Ulam Rassias stability of the functional equation $$f(2x+y)+f(2x-y)=4(f(x+y)+f(x-y))-{3/7}(f(2y)-2f(y))+2f(2x)-8f(x).$$

Satbility of Ternary Homomorphisms via Generalized Jensen Equation

In this paper, we establish the generalized Hyers--Ulam--Rassias stability of homomorphisms between ternary algebras associted to the generalized Jensen functional equation $r f(\frac{sx+ty}{r}) = s f(x) + t f(y)$.

Stability of a mixed type quadratic, cubic and quartic functional equation

In this paper, we obtain the general solution and the generalized Hyers-Ulam Rassias stability of the functional equation $$3(f(x+2y)+f(x-2y))=12(f(x+y)+f(x-y))+4f(3y)-18f(2y)+36f(y)-18f(x).$$

Approximate $(σ-τ)$-Contractibility

In this paper, the generalized Hyers--Ulam--Rassias stability of $(σ-τ)$-derivations on normed algebras into Banach bimodules is established. We introduce the notion of approximate $(σ-τ)$-contractibility and prove that a Banach algebra is $(σ-τ)$-contractible if and only if it is approximately $(σ-τ)$-Contractible.

Stability of the Jensen--type functional equation in ternary Banach algebras: An alternative fixed point approach

Using fixed point methods, we prove the generalized Hyers--Ulam--Rassias stability of ternary homomorphisms, and ternary multipliers in ternary Banach algebras for the Jensen--type functional equation $$f(\frac{x+y+z}{3})+f(\frac{x-2y+z}{3})+f(\frac{x+y-2z}{3})= f(x).$$

用不动点方法研究巴拿赫代数上对合的稳定性

Stability of involutions on Banach Algebra by fixed point method

该研究采用Jensen函数方程稳定性的不动点方法，证明巴拿赫代数上对合的Hyers-Ulam-Rassias稳定性与超稳定性，还得到使带近似对合的巴拿赫代数成为$C^*$-代数的条件。

On the Stability of J*-Homomorphisms

The main purpose of this paper is to prove the generalized Hyers-Ulam-Rassias stability of J*-homomorphisms between J*-algebras.

Solution and stability of generalized mixed type cubic, quadratic and additive functional equation in quasi-Banach spaces

In this paper, we achieve the general solution and the generalized Hyers-Ulam-Rassias stability of the following functional equation $$f(x+ky)+f(x-ky)=k^2f(x+y)+k^2f(x-y)+2(1-k^2)f(x)\eqno {2 cm}$$for fixed integers $k$ with $k\neq0,\pm1$ in the quasi-Banach spaces.

Hyperstability of orthogonally 3-Lie homomorphism: an orthogonally fixed point approach

In this paper, by using the orthogonally fixed point method, we prove the Hyers-Ulam stability and the hyperstability of orthogonally 3-Lie homomorphisms for additive $ρ$-functional equation in 3-Lie algebras.\\ Indeed, we investigate the Hyers-Ulam stability and the hyperstability of the system of functional equations \begin{eqnarray*} \left\{ \begin{array}{ll} f(x+y)-f(x)-f(y)= ρ(2f(\frac{x+y}{2})+ f(x)+ f(y)),\\ f([[x,y],z])=[[f(x),f(y)],f(z)] \end{array} \right. \end{eqnarray*} in 3-Lie algebras (where $ρ$ is a fixed real number with $ρ\ne 1$).

On the stability of generalized mixed type quadratic and quartic functional equation in quasi-Banach spaces

In this paper, we establish the general solution of the functional equation $$f(nx+y)+f(nx-y)=n^2f(x+y)+n^2f(x-y)+2(f(nx)-n^2f(x))-2(n^2-1)f(y)\eqno {0 cm}$$for fixed integers $n$ with $n\neq0,\pm1$ and investigate the generalized Hyers-Ulam-Rassias stability of this equation in quasi-Banach spaces.

Nearly generalized Jordan derivations

Let $A$ be an algebra and let $X$ be an $A$-bimodule. A $\Bbb C-$linear mapping $d:A \to X$ is called a generalized Jordan derivation if there exists a Jordan derivation (in the usual sense) $δ:A \to X$ such that $d(a^2)=ad(a)+δ(a)a$ for all $a \in A.$ The main purpose of this paper to prove the Hyers-Ulam-Rassias stability and superstability of the generalized Jordan derivations.

Hilbert空间的近似等距

Approximate isometries of Hilbert spaces

通过移除满射性假设，改进了实Hilbert空间等距映射的Hyers-Ulam稳定性结果。

Solution and Stability of a Mixed Type Functional Equation

In this paper, we obtain the general solution and investigate the generalized Hyers-Ulam-Rassias stability for the new mixed type additive and cubic functional equation $$3f(x+3y) - f(3x + y)=12[f(x+y)+f(x-y)]-16[f(x)+f(y)] + 12f(2y) - 4f(2x).$$ As some corollaries, we show that the stability of this equation can be controlled by the sum and product of powers of norms.

Ulam stability of an additive-quadratic functional equation in F-space and quasi-Banach spaces

By adopting the direct method and fixed point method, we prove that the Hyers-Ulam stability of the following additive-quadratic functional equation \begin{equation} f(x+y, z+w)+f(x-y, z-w)-2 f(x, z)-2 f(x, w)=0 \end{equation} in $β$-homogeneous $F$-spaces and quasi-Banach spaces. There are some differences that we consider the target space with the $β$-homogeneous norm and quasi-norm. Overcoming the $β$-homogeneous norm and quasi-norm bottlenecks, we get some new results.

The stability of a quadratic type functional equation with the fixed point alternative

In this paper, we achieve the general solution and the generalized Hyers-Ulam-Rassias stability for the quadratic type functional equation &f(x+y+2cz)+f(x+y-2cz)+c^2f(2x)+c^2f(2y) &=2[f(x+y)+c^2f(x+z)+c^2f(x-z)+c^2f(y+z)+c^2f(y-z)] {2.6 cm} for fixed integers $c$ with $c\neq0,\pm1$, by using the fixed point alternative.

$θ$-derivations on $JB^*$-triples

We introduce the concept of $θ$-derivations on $JB^*$-triples, and prove the Hyers--Ulam--Rassias stability of $θ$-derivations on $JB^*$-triples.

Stability of Generalized Jensen Equation on Restricted Domains

In this paper, we establish the conditional Hyers-Ulam-Rassias stability of the generalized Jensen functional equation $r f \left (\frac{sx+ty}{r}) = s g(x) + t h(y)$ on various restricted domains such as inside balls, outside balls, and punctured spaces. In addition, we prove the orthogonal stability of this equation and study orthogonally generalized Jensen mappings on Balls in inner product spaces.

Approximate $C^*$-Ternary Ring Homomorphisms

In this paper, we establish the generalized Hyers--Ulam--Rassias stability of $C^*$-ternary ring homomorphisms associated to the Trif functional equation \begin{eqnarray*} d \cdot C_{d-2}^{l-2} f(\frac{x_1+... +x_d}{d})+ C_{d-2}^{l-1}\sum_{j=1}^d f(x_j) = l \cdot \sum_{1\leq j_1< ... < j_l\leq d} f(\frac{x_{j_1} + ... + x_{j_l}}{l}). \end{eqnarray*}

Bi-additive s-functional inequalities and biderivations in modular spaces

In this article, by using the fixed point method, we prove the generalized Hyers--Ulam stability of biderivations from an algebra to a modular space, associated to bi-additive s-functional inequalities.

On approximate cubic homomorphisms

In this paper, we investigate the generalized Hyers--Ulam--Rassias stability of the system of functional equations $$f(xy)=f(x)f(y), \qquad\qquad. f(2x+y)+f(2x-y)=2f(x+y)+2f(x-y)+12f(x), $$ on Banach algebras. Indeed we establish the superstability of above system by suitable control functions.

Fuzzy stability of additive--quadratic functional equations

In this paper we investigate the generalized Hyers- Ulam stability of the functional equation $$f (2x +y)+f (2x -y)= f (x + y)+ f (x -y)+2f (2x)-2f (x)$$ in fuzzy Banach spaces.

Stability of generalized mixed type additive-quadratic-cubic functional equation in non-Archimedean spaces

In this paper, we prove generalized Hyres--Ulam--Rassias stability of the mixed type additive, quadratic and cubic functional equation $$f(x+ky)+f(x-ky)=k^2f(x+y)+k^2f(x-y)+2(1-k^2)f(x)$$ for fixed integers $k$ with $k\neq0,\pm1$ in non-Archimedean spaces.

Stability of ternary Jordan homomorphisms and derivations associated to the generalized Jensen equation

In this paper, we establish the generalized Hyers-Ulam stability of Jordan homomorphisms and Jordan derivations between ternary algebras via the generalized Jensen equation $rf(\frac{sx+ty}{r})=sf(x)+tf(y)$.

Approximate Generalized Additive-Quadratic Functional Equations on Ternary Banach Algebras

In this paper, we introduce the concept of j-hom-derivation, $j\in\{1,2\}$ and solve the new generalized additive-quadratic functional equations in the sense of ternary Banach algebras. Moreover, using the fixed point method, we prove its Hyers-Ulam stability.

Approximation of general 3-variable Jensen $ρ$-functional inequalities in complex Banach spaces

In this paper, we introduce and investigate general 3-variable Jensen $ρ$-functional equation, and prove the Hyers-Ulam stability of the Jensen functional equations associated with the general 3-variable Jensen $ρ$-functional inequalities in complex Banach spaces.

Perturbations of isometries between Banach spaces

We prove a very general theorem concerning the estimation of the expression $\|T(\frac{a+b}{2}) - \frac{Ta+Tb}{2}\|$ for different kinds of maps $T$ satisfying some general perurbated isometry condition. It can be seen as a quantitative generalization of the classical Mazur-Ulam theorem. The estimates improve the existing ones for bi-Lipschitz maps. As a consequence we also obtain a very simple proof of the result of Gevirtz which answers the Hyers-Ulam problem and we prove a non-linear generalization of the Banach-Stone theorem which improves the results of Jarosz and more recent results of D…

Stability of a functional equation deriving from cubic and quartic functions

In this paper, we obtain the general solution and the generalized Ulam-Hyers stability of the cubic and quartic functional equation &4(f(3x+y)+f(3x-y))=-12(f(x+y)+f(x-y)) &+12(f(2x+y)+f(2x-y))-8f(y)-192f(x)+f(2y)+30f(2x).

On the Orthogonal Stability of the Pexiderized Quadratic Equation

The Hyers--Ulam stability of the conditional quadratic functional equation of Pexider type f(x+y)+f(x-y)=2g(x)+2h(y), x\perp y is established where \perp is a symmetric orthogonality in the sense of Ratz and f is odd.

On the stability of the linear functional equation in a single variable on complete metric groups

In this paper we obtain a result on Hyers-Ulam stability of the linear functional equation in a single variable $f(φ(x)) = g(x) \cdot f(x)$ on a complete metric group.

Stability of cubic and quartic functional equations in non-Archimedean spaces

We prove generalized Hyres-Ulam-Rassias stability of the cubic functional equation $f(kx+y)+f(kx-y)=k[f(x+y)+f(x-y)]+2(k^3-k)f(x)$ for all $k\in \Bbb N$ and the quartic functional equation $f(kx+y)+f(kx-y)=k^2[f(x+y)+f(x-y)]+2k^2(k^2-1)f(x)-2(k^2-1)f(y)$ for all $k\in \Bbb N$ in non-Archimedean normed spaces.

Stability of additive functional equation on discrete quantum semigroups

We show that noncommutative analog of additive functional equation has Hyers-Ulam stability on amenable discrete quantum (semi)groups. This generalizes an old classical result.

Approximately Vanishing of Topological Cohomology Groups

In this paper, we establish the Pexiderized stability of coboundaries and cocycles and use them to investigate the Hyers--Ulam stability of some functional equations. We prove that for each Banach algebra $A$, Banach $A$-bimodule $X$ and positive integer $n, H^n(A,X)=0$ if and only if the $n$-th cohomology group approximately vanishes.

Approximately Lie ternary $(σ,τ,ξ)-$derivations on Banach ternary algebras

Let $A$ be a Banach ternary algebra over a scalar field $\Bbb R$ or $\Bbb C$ and $X$ be a ternary Banach $A-$module. Let $σ,τ$ and $ξ$ be linear mappings on $A$, a linear mapping $D:(A,[]_A)\to (X,[]_X)$ is called a Lie ternary $(σ,τ,ξ)-$derivation, if $$D([abc]_A)=[[D(a)bc]_X]_{(σ,τ,ξ)}+[[D(b)ac]_X]_{(σ,τ,ξ)}+[[D(c)ba]_X]_{(σ,τ,ξ)},$$ for all $a,b,c\in A$, where $[abc]_{(σ,τ,ξ)}=aτ(b)ξ(c)-σ(c)τ(b)a.$ In this paper, we investigate the generalized Hyers--Ulam--Rassias stability of Lie ternary $(σ,τ,ξ)-$derivations on Banach ternary algebras.

On the stability of the orthogonal Pexiderized Cauchy equation

We investigate the stability of Pexiderized mappings in Banach modules over a unital Banach algebra. As a consequence, we establish the Hyers--Ulam stability of the orthogonal Cauchy functional equation of Pexider type $f_1(x+y)=f_2(x)+f_3(y)$, $x\perp y$ in which $\perp$ is the orthogonality in the sense of Ratz.

On the stability of a generalized additive functional equation

We consider Hyers-Ulam stability of a functional equation for continuous functions on a space on which a topological group acts, analogous to the additive functional equation on a group. We show, among other things, that our generalized additive equation, for continuous functions on a homogenous space of a strongly amenable topological group, is stable provided that the canonical projection from that group to its homogenous space is a fiber bundle.

Stability of a new generalized reciprocal type functional equation

In this paper, we investigate the generalized Hyers-Ulam stability of the following reciprocal type functional equation \begin{equation*}f(2x+y)+f(2x-y)=\frac{2f(x)f(y)\displaystyle{\sum_{\substack{k=0\\ \text{$k$ is even}}}^{ l}2^{l-k}\binom{l}{k}f(x)^{\frac{k}{l}}f(y)^{\frac{l-k}{l}}}}{\left(4f(y)^{\frac{2}{l}}-f(x)^{\frac{2}{l}}\right)^l}\end{equation*} in non-zero real and non-Archimedean spaces.

Further stability results of the functional equation $f(2x+y)+f\left(\frac{x+y}{2}\right) =\frac{2f(x)f(y)}{f(x)+f(y)}+\frac{2f(x+y)f(y-x)}{3f(y-x)-f(x+y)}$

In this paper, we investigate the generalized Hyers-Ulam stability of the following reciprocal functional equation \begin{equation*}f(2x+y)+f\left(\frac{x+y}{2}\right) =\frac{2f(x)f(y)}{f(x)+f(y)}+\frac{2f(x+y)f(y-x)}{3f(y-x)-f(x+y)}\end{equation*} in non-Archimedean space using a direct method.

Stability of Derivations on Hilbert $C^*$-Modules

Consider the functional equation ${\mathcal E}_1(f) = {\mathcal E}_2(f) ({\mathcal E})$ in a certain framework. We say a function $f_0$ is an approximate solution of $({\mathcal E})$ if ${\mathcal E}_1(f_0)$ and ${\mathcal E}_2(f_0)$ are close in some sense. The stability problem is whether or not there is an exact solution of $({\mathcal E})$ near $f_0$. In this paper, the stability of derivations on Hilbert $C^*$-modules is investigated in the spirit of Hyers--Ulam--Rassias.

二次函数方程在模空间中的稳定性

Stability of quadratic functional equation in modular spaces

该文考察一个二次函数方程分别在带或不带Δ₂条件的模空间及β-齐次Banach空间中的Hyers-Ulam稳定性。

Stability of Euler-Lagrange type cubic functional equations in quasi-Banach spaces

In this paper, we study the generalized Hyers-Ulam stability of Euler-Lagrange type cubic functional equation of the form \begin{align*} 2mf(x + my) + 2f(mx - y) = (m^3 + m)[f(x+ y) + f(x - y)] + 2(m^4 - 1)f(y) \end{align*} for all $x,y \in X$, where $m$ is a fixed scalar such that $m \neq 0,1$, and $f$ is a map from a quasi-normed space $X$ to a quasi-Banach space $Y$ over the same field with $X$ by applying the alternative fixed point theorem.

模空间中根式函数方程的稳定性

On the stability of radical functional equation in modular space

该研究在模空间中利用直接法和不动点定理，证明了一类含奇整数参数s（s≥3）且|q|≤1的根式函数方程的广义Hyer-Ulam稳定性，拓展了函数方程稳定性的研究范畴。

混合型加性-三次Jensen泛函方程在非阿基米德$(n, β)$赋范空间中的稳定性

Stability of Mixed Type Additive-Cubic Jensen Functional Equation in Non-Archimedean $(n, β)$ Normed Spaces

本文研究了混合型加性-三次Jensen泛函方程在非阿基米德$(n, β)$赋范空间中的Hyers-Ulam稳定性。