给出非单C*-代数α-比较性的等价刻画:当每个τ∈QT(A H)均为忠实时,A具有α-比较性,当且仅当对于任意的〈a〉,〈b〉∈Cu(A)且〈a〉∝〈b〉,若a·dτ(a)〈dτ(b)(∨τ∈QT(A H)),且〈a〉≤〈b〉在Cu(A)中成立;一般地,当QT(A H)≠θ,A具有α-比较性,当且仅当对于任意的〈a〉,〈b〉∈Cu(A),若存在η〉0,使得dτ(a)≤(a^-1-η)dτ(b)(Vτ)∈QT(A H)),刚〈a〉≤〈b〉在Cu(A)中成立。
Abstract This note is to give such characterizations of the a-comparison property for non-simple C*-algebras: when each τ∈QT(A H)is faithful, A has the a-comparison property, if and only if, for any 〈a〉,〈b〉∈Cu(A) with 〈a〉∝〈b〉,a·dτ(a)〈dτ(b)(∨τ∈QT(A H))implies (a) ≤(b) in Cu(A);in general, when QT(A H)≠θ,A has the a-comparison property, if and only if, for any 〈a〉,〈b〉∈Cu(A),if there is some η〉0such that dτ(a)≤(a^-1-η)dτ(b)(Vτ)∈QT(A H)),then 〈a〉≤〈b〉 in Cu(A).