5 papers
Relation morphisms of directed graphs
Gilles G. de Castro, Francesco D'Andrea, Piotr M. Hajac
Associating graph algebras to directed graphs leads to both covariant and contravariant functors from suitable categories of graphs to the category k-Alg of algebras and algebra ho…
Graded Locally Finite and Just Infinite Steinberg Algebras
Giuliano Boava, Gilles G. de Castro, Daniel Gonçalves +1
We study graded locally finite and graded just infinite Steinberg algebras of ample Hausdorff groupoids. For gradings by discrete groups induced by a cocycle, we characterize finit…
The functoriality of moves on graphs and the extended covariant functoriality of graph algebras
Gilles G. de Castro, Piotr M. Hajac, Mateusz Lowiel +1
Combinatorics of graphs is a very powerful tool to unravel various properties of graph algebras. In particular, isomorphisms between graph algebras are often implemented by moves b…
The dynamical structure of partial group algebras with relations, with applications to subshift algebras
Giuliano Boava, Gilles G. de Castro, Daniel Gonçalves +1
We introduce partial group algebras with relations in a purely algebraic framework. Given a group and a set of relations, we define an algebraic partial action and prove that the r…
Ideals of étale groupoid algebras with coefficients in a sheaf with applications to topological dynamics
Gilles G. de Castro, Daniel Gonçalves, Benjamin Steinberg
We prove the Effros-Hahn conjecture for groupoid algebras with coefficients in a sheaf, obtaining as a consequence a description of the ideals in skew inverse semigroup rings. We a…