Finite sums of projections in purely infinite simple C*-algebras with torsion 𝐾₀

Kaftal, Victor; Ng, P. W.; Zhang, Shuang

doi:10.1090/S0002-9939-2012-11152-9

Finite sums of projections in purely infinite simple C*-algebras with torsion $K_0$
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by Victor Kaftal, P. W. Ng and Shuang Zhang PDF

Proc. Amer. Math. Soc. 140 (2012), 3219-3227 Request permission

Abstract:

Assume that $\mathscr {A}$ is a purely infinite simple C*-algebra whose $K_0$ is a torsion group, namely, contains no free element. Then a positive element $a\in \mathscr {A}$ can be written as a finite sum of projections in $\mathscr {A}$ if and only if either $a$ is a projection or $\|a\|>1$.

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