Commutant of an operator algebra
= Commutant of an operator algebra
{title2=$A\prime=\operatorname{End}_A(T)$}
The commutant of $A\subseteq\operatorname{End}(T)$ is $A\prime=\{b:ba=ab\text{ for all }a\in A\}$. This centralizer is an operator algebra. The <double-centralizer theorem for semisimple operator algebras> and <Schur–Weyl duality> use this meaning, which is distinct from the centralizer of a single element of a group.