The center of a Kumjian-Pask algebra
  The Kumjian-Pask algebras are path algebras associated to higher-rank graphs, and generalize the Leavitt path algebras. We study the center of simple Kumjian-Pask algebras and characterize commutative Kumjian-Pask algebras. 
Jonathan Henry Brown and Astrid an Huef
math.RA