Convolution algebras for relational groupoids and reduction

  title={Convolution algebras for relational groupoids and reduction},
  author={Iv{\'a}n A. Contreras and Nima Moshayedi and Konstantin Wernli},
  journal={Pacific Journal of Mathematics},
We introduce the notions of relational groupoids and relational convolution algebras. We provide various examples arising from the group algebra of a group $G$ and a given normal subgroup $H$. We also give conditions for the existence of a Haar system of measures on a relational groupoid compatible with the convolution, and we prove a reduction theorem that recovers the usual convolution of a Lie groupoid. 

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