**$Surj$** (or **$Set_{surj}$**) is the wide subcategory of the topos Set with its morphisms restricted to epimorphisms (surjective functions).

**$FinSurj$** (or **$FinSet_{surj}$**) is the full subcategory of $Surj$ spanned by the finite sets. It is the free symmetric monoidal category generated by a commutative semigroup.

- Cole Comfort,
*A diagrammatic approach to networks of spans and relations*, PhD thesis, University of Oxford, 2023, web.

Last revised on August 3, 2024 at 16:07:48. See the history of this page for a list of all contributions to it.