PlanetPhysics/Category of Borel Groupoids

The category of Borel groupoids ${\mathcal {G}}^{B}$ has, as its objects, all Borel groupoids Failed to parse (unknown function "\grp"): {\displaystyle \grp_B} and, as its morphisms the Borel groupoid homomorphisms $h_{B}$ between Borel groupoids.