Completely inverse -groupoids
arXiv:1305.6856 · doi:10.1007/s00233-013-9465-z
Abstract
A completely inverse -groupoid is a groupoid satisfying the identities , and , where is a unique inverse of , that is, and . First we study some fundamental properties of such groupoids. Then we determine certain fundamental congruences on a completely inverse -groupoid; namely: the maximum idempotent-separating congruence, the least -group congruence and the least -unitary congruence. Finally, we investigate the complete lattice of congruences of a completely inverse -groupoids. In particular, we describe congruences on completely inverse -groupoids by their kernel and trace.