Ext Classes and Embeddings for C*-Algebras of Graphs with Sinks

摘要

We consider directed graphs E obtained by adding a sink to a fixed graph G. We associate an element of Ext(C*(G)) to each such E,and show that the classes of two such graphs are equal inExt(C*(G)) if and only if the associated C*-algebraof one can be embedded as a full corner in theC*-algebra of the other in a particular way. If everyloop in G has an exit, then we are able to use thisresult to generalize some known classificationtheorems for C*-algebras of graphs with sinks.