Connes amenability of the second dual of Arens regular Banach algebras

In this paper we study the Connes amenability of the second dual of Arens regular Banach algebras. Of course we provide a partial answer to the question posed by Volker Runde. Also we fined the necessary and sufficient conditions for the second dual of an Arens regular module extension Banach algebra to be Connes amenable when the module is reflexive.Comment: 5 pages. To appear in Italian J. of Pure and Appl. Mat

On approximate n-ring homomorphisms and n-ring derivations

Let $A,B$ be two rings and let $X$ be an $A-$module. An additive map $h: A\to B$ is called n-ring homomorphism if $h(\Pi^n_{i=1}a_i)=\Pi^n_{i=1}h(a_i),$ for all $a_1,a_2, ...,a_n \in {A}$. An additive map $D: A\to X$ is called $n$-ring derivation if $$D(\Pi^n_{i=1}a_i)=D(a_1)a_2... a_n+a_1D(a_2)a_3... a_n+... +a_1a_2... a_{n-1}D(a_n),$$ for all $a_1,a_2, ...,a_n \in {\mathcal A}$. In this paper we investigate the Hyers-Ulam-Rassias stability of $n$-ring homomorphisms and n-ring derivations

Left introverted subspaces of duals of Banach algebras and WEAK∗−WEAK^*-continuous derivations on dual Banach algebras

Let $X$ be a left introverted subspace of dual of a Banach algebra. We study $Z_t(X^*),$ the topological center of Banach algebra $X^*$. We fined the topological center of (X\cA)^*, when \cA has a bounded right approximate identity and \cA\subseteq X^*. So we introduce a new notation of amenability for a dual Banach algebra $\cal A$. A dual Banach algebra $\cal A$ is weakly Connes-amenable if the first $weak^*-$continuous cohomology group of $\cal A$ with coefficients in $\cal A$ is zero; i.e., $H^1_{w^*}(\cal A, \cal A)=\{o\}$. We study the weak Connes-amenability of some dual Banach algebras.Comment: 10 page

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).$

n-Jordan homomorphisms

Let $n\in \Bbb N,$ and let $A,B$ be two rings. An additive map $h: A\to B$ is called n-Jordan homomorphism if $h(a^n)=(h(a))^n$ for all $a \in {A}$. Every Jordan homomorphism is an n-Jordan homomorphism, for all $n\geq 2,$ but the converse is false, in general. In this paper we investigate the n-Jordan homomorphisms on Banach algebras. Indeed some results related to continuity are given as well

Jordan ∗−*-homomorphisms between unital C∗−C^*-algebras

Let $A,B$ be two unital $C^*-$algebras. We prove that every almost unital almost linear mapping $h:A\longrightarrow B$ which satisfies $h(3^nuy+3^nyu) = h(3^nu)h(y)+h(y)h(3^nu)$ for all $u\in U(A)$, all $y\in A$, and all $n = 0, 1, 2,...$, is a Jordan homomorphism. Also, for a unital $C^*-$algebra $A$ of real rank zero, every almost unital almost linear continuous mapping $h:A\longrightarrow B$ is a Jordan homomorphism when $h(3^nuy+3^nyu) = h(3^nu)h(y)+h(y)h(3^nu)$ holds for all $u\in I_1(A_{sa})$, all $y\in A,$ and all $n = 0, 1, 2,... ~$. Furthermore, we investigate the Hyers--Ulam--Rassias stability of Jordan $*-$homomorphisms between unital $C^*-$algebras by using the fixed points methods

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

On the Mazur--Ulam theorem in fuzzy normed spaces

In this paper, we establish the Mazur--Ulam theorem in the fuzzy strictly convex real normed spaces.Comment: 4 page

Derivations into n-th duals of ideals of Banach algebras

We introduce two notions of amenability for a Banach algebra $\cal A$. Let $n\in \Bbb N$ and let $I$ be a closed two-sided ideal in $\cal A$, $\cal A$ is $n-I-$weakly amenable if the first cohomology group of $\cal A$ with coefficients in the n-th dual space $I^{(n)}$ is zero; i.e., $H^1({\cal A},I^{(n)})=\{0\}$. Further, $\cal A$ is n-ideally amenable if $\cal A$ is $n-I-$weakly amenable for every closed two-sided ideal $I$ in $\cal A$. We find some relationships of $n-I-$ weak amenability and $m-J-$ weak amenability for some different m and n or for different closed ideals $I$ and $J$ of $\cal A$.Comment: 11 pag

Some applications of the generalized Bernardi - Libera - Livingston integral operator on univalent functions

In this paper by making use of the generalized Bernardi - Libera - Livingston integral operator we introduce and study some new subclasses of univalent functions. Also we investigate the relations between those classes and the classes which are studied by Jin-Lin Liu