Groupoid and Inverse Semigroup Presentations of Ultragraph -Algebras
arXiv:0709.2281
Abstract
Inspired by the work of Paterson on -algebras of directed graphs, we show how to associate a groupoid to an ultragraph in such a way that the -algebra of is canonically isomorphic to Tomforde's -algebra . The groupoid is built from an inverse semigroup naturally associated to .