arXiv subjects
Publications and source records attributed to Kaijia Luo.
Let $D$ be a noncommutative division ring and let $R = M_{m}(D)$ with $m > 1$. We characterize additive mappings $f,$ $g:R\rightarrow R$ satisfying the identity $f(X) = X^{n}g(X^{-1})$ for every invertible element $X$ in $R$, where $n$ is a nonnegative integer. We show that the solutions are precisely given by $f = g$ and $f(X) = Xf(I)$ for all $X$ in $R$. Moreover, if $n \neq2$, both $f$ and $g$ are identically zero.
The purpose of this paper is to characterize several classes of functional identities involving inverses with related mappings from a unital Banach algebra $\mathcal{A}$ over the complex field into a unital $\mathcal{A}$-bimodule $\mathcal{M}$. Let $N$ be a fixed invertible element in $\mathcal{A}$, $M$ be a fixed element in $\mathcal{M}$, and $n$ be a positive integer. We investigate the forms of additive mappings $f$, $g$ from $\mathcal{A}$ into $\mathcal{M}$ satisfying one of the following identities: \begin{equation*} \begin{aligned} &f(A)A- Ag(A) = 0\\ &f(A)+ g(B)\star A= M\\ &f(A)+A^{n}g(A^{-1})=0\\ &f(A)+A^{n}g(B)=M \end{aligned} \qquad \begin{aligned} &\text{for each invertible element}~A\in\mathcal{A}; \\ &\text{whenever}~ A,B\in\mathcal{A}~\text{with}~AB=N;\\ &\text{for each invertible element}~A\in\mathcal{A}; \\ &\text{whenever}~ A,B\in\mathcal{A}~\text{with}~AB=N, \end{aligned} \end{equation*} where $\star$ is either the Jordan product $A\star B = AB+BA$ or the Lie product $A\star B = AB-BA$.
Let $\mathfrak{M}(\mathbb{D}, m, n, P)$ be the ring of all $m \times n$ matrices over a division ring $\mathbb{D}$, with the product given by $A \bullet B=A P B$, where $P$ is a fixed $n \times m$ matrix over $\mathbb{D}$. When $2\leq m, n <\infty$ and $\operatorname{rank} P \geq 2$, we demonstrate that every element in $\mathcal{A}=\mathfrak{M}(\mathbb{D}, m, n, P)$ is a sum of finite products of pairs of commutators. We also estimate the minimal number $N$ such that $\mathcal{A}= \sum^N [\mathcal{A}, \mathcal{A}][\mathcal{A}, \mathcal{A}]$. Furthermore, if $\operatorname{char}\mathbb{D}\neq 2$, we prove that $\mathfrak{M}(\mathbb{D}, m, n, P)$ is additively spanned by Jordan products of idempotents. For a field $\mathbb{F}$ with $\operatorname{char}\mathbb{F}\neq 2, 3$, we show that the Munn algebra $\mathfrak{M}(\mathbb{F}, m, n, P)$ is zero product determined and zero Jordan product determined.
Let $\mathcal{A}$ be a unital Banach $*$-algebra and $\mathcal{M}$ be a unital $*$-$\mathcal{A}$-bimodule. If $W$ is a left separating point of $\mathcal{M}$, we show that every $*$-derivable mapping at $W$ is a Jordan derivation, and every $*$-left derivable mapping at $W$ is a Jordan left derivation under the condition $W \mathcal{A}=\mathcal{A}W$. Moreover we give a complete description of linear mappings $δ$ and $τ$ from $\mathcal{A}$ into $\mathcal{M}$ satisfying $δ(A)B^*+Aτ(B)^*=0$ for any $A, B\in \mathcal{A}$ with $AB^*=0$ or $δ(A)\circ B^*+A\circτ(B)^*=0$ for any $A, B\in \mathcal{A}$ with $A\circ B^*=0$, where $A\circ B=AB+BA$ is the Jordan product.