RO  EN
IMCS/Publications/BASM/Issues/BASM n.2 (12), 1993/

On the commutator of two operators in sandwiches. (Russian)

Authors: Ufnarovskij V. A.

Abstract

Let $C = AB-BA$ be a matrix of rang 1. Three different proofs, that $A$ and $B$ has nontrivial common invariant subspace are suggested. The last proof is based on the more general result: if $a$ and $b$ are generators of an associative algebra $A$ over field $K$ of zero characteristic and for $c=[a,b]$ we have $c(Ac\cap [A,A]) = 0$, then $Ac \subseteq [A,A]$.

Institutul de Matematica Academia de Ştiinţe a Moldovei
str. Academiei 5, Chişinău MD-2028, Moldova