Projections in free product C*-algebras

被引:29
作者
Dykema, KJ [1 ]
Rordam, M [1 ]
机构
[1] Odense Univ, Dept Math & Comp Sci, DK-5230 Odense M, Denmark
关键词
D O I
10.1007/s000390050046
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
Consider the reduced free product of C*-algebras, (A, phi) = (A(1),phi(1))* (A(2),phi(2)), with respect to states phi(1) and phi(2) that are faithful. If phi(1) and phi(2) are traces, if the so-called Avitzour conditions are satisfied, (i.e. A(1) and A(2) are not "too small" in a specific sense) and if A(1) and A(2) are nuclear, then it is shown that the positive cone, K-0(A)(+), of the K-0-group of A consists of those elements g is an element of K-0(A) for which g = 0 or K-0(phi)(g) > 0. Thus, the ordered group K-0(A) is weakly unperforated. If, on the other hand, phi(1) or phi(2) is not a trace and if a certain condition weaker than the Avitzour conditions holds, then A is properly infinite.
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页码:1 / 16
页数:16
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