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math.RA2020
Ultragraph algebras via labelled graph groupoids, with applications to generalized uniqueness theorems
Gilles G. de Castro, Daniel Gonçalves, Daniel W. van Wyk
An ultragraph gives rise to a labelled graph with some particular properties. In this paper we describe the algebras associated to such labelled graphs as groupoid algebras. More p…
math.OA2020
Infinite sum relations on universal C*-algebras
Giuliano Boava, Gilles G. de Castro
We extend the usual theory of universal C*-algebras from generators and relations in order to allow some relations to be described using the strong operator topology. In particular…
math.RA2020
Coverages on Inverse Semigroups
Gilles G. de Castro
First we give a definition of a coverage on a inverse semigroup that is weaker than the one gave by a Lawson and Lenz and that generalizes the definition of a coverage on a semilat…