The ordered K-theory of a full extension

Abstract

Let A be a C*-algebra with real rank zero which has the stable weak cancellation property. Let I be an ideal of A such that I is stable and satisfies the corona factorization property. We prove that 0->I->A->A/I->0 is a full extension if and only if the extension is stenotic and K-lexicographic. As an immediate application, we extend the classification result for graph C*-algebras obtained by Tomforde and the first named author to the general non-unital case. In combination with recent results by Katsura, Tomforde, West and the first author, our result may also be used to give a purely K-theoretical description of when an essential extension of two simple and stable graph C*-algebras is again a graph C*-algebra.

Version IV: No changes to the text. We only report that Theorem 4.9 is not correct as stated. See arXiv:1505.05951 for more details. Since Theorem 4.9 is an application to the main results of the paper, the main results of this paper are not affected by the error. Version III comments: Some typos and errors corrected. Some references added

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• The complete classification of unital graph $C^{\ast }$-algebras: Geometric and strong
• A note on non-unital absorbing extensions
• Classification of graph C*-algebras with no more than four primitive ideals
• The Ranges of K-theoretic Invariants for Nonsimple Graph Algebras
• The extension problem for graph $C^{\ast }$-algebras
• Corrigendum to "Classifying C*-algebras with both finite and infinite subquotients"