arXiv subjects

Zhu Jun

Publications and source records attributed to Zhu Jun.

2 recordsLinked to original sources

arXiv2011

Jordan product determined points in matrix algebras

Let $M_n(R)$ be the algebra of all $n\times n$ matrices over a unital commutative ring $R$ with 6 invertible. We say that $A\in M_n(R)$ is a Jordan product determined point if for every $R$-module $X$ and every symmetric $R$-bilinear map $\{\cdot, \cdot\}$ : $M_n(R)\times M_n(R)\to X$ the following two conditions are equivalent: (i) there exists a fixed element $w\in X$ such that $\{x,y\}=w$ whenever $x\circ y=A$, $x,y\in M_n(R)$; (ii) there exists an $R$-linear map $T:M_n(R)^2\to X$ such that $\{x,y\}=T(x\circ y)$ for all $x,y\in M_n(R)$. In this paper, we mainly prove that all the matrix units are the Jordan product determined points in $M_n(R)$ when $n\geq 3$. In addition, we get some corollaries by applying the main results.

math.OA↗

arXiv2010

All-derivable points in nest algebras

Suppose that $\mathscr{A}$ is an operator algebra on a Hilbert space $H$. An element $V$ in $\mathscr{A}$ is called an all-derivable point of $\mathscr{A}$ for the strong operator topology if every strong operator topology continuous derivable mapping $ϕ$ at $V$ is a derivation. Let $\mathscr{N}$ be a complete nest on a complex and separable Hilbert space $H$. Suppose that $M$ belongs to $\mathscr{N}$ with $\{0\}\neq M\neq\ H$ and write $\hat{M}$ for $M$ or $M^{\bot}$. Our main result is: for any $Ω\in alg\mathscr{N}$ with $Ω=P(\hat{M})ΩP(\hat{M})$, if $Ω|_{\hat{M}}$ is invertible in $alg\mathscr{N}_{\hat{M}}$, then $Ω$ is an all-derivable point in $alg\mathscr{N}$ for the strong operator topology.

math.OA↗