设T是复数域上的代数,T的换位子[T,T]指{[a,b]:a,b∈T}的线性扩张.本文给出了Nest代数T(N)的换位子[T(N),T(N)]的σ-弱算子拓扑闭包——↑[T(N),T(N)]^σ-wot的刻画,和TAF代数T的换位子[T,T]的范数闭包—↑[T,T]的几种刻画,进一步得到—↑[T,T]是T的理想.
Let T be an associative algebra over the complex filed, and the commutator [T, T] of T be the linear span of the set {[a, b] : a, b ∈ T}. We describe the σ - wot closure of the commutator of a nest algebra and the norm closure of the commutator of an TAF algebra.