Multiplicative derivations on rank-$s$ matrices for relatively small $s$

Abstract

Let $n$ and $s$ be fixed integers such that $n\ge 2$ and $1\le s\le \frac{n}{2}$. Let $M_n(\mathbb{K})$ be the ring of all $n\times n$ matrices over a field $\mathbb{K}$. If a map $\delta :M_n(\mathbb{K})\to M_n(\mathbb{K})$ satisfies that $\delta (xy)=\delta (x)y+x\delta (y)$ for any two rank-$s$ matrices $x,y\in M_n(\mathbb{K})$, then there exists a derivation $D$ of $M_n(\mathbb{K})$ such that $\delta (x)=D(x)$ holds for each rank-$k$ matrix $x\in M_n(\mathbb{K})$ with $0\le k\le s$.

9 pages