The Azimuth Project


A ring is a set equipped with two binary operations, addition and multiplication, where the addition makes the set a group, and the multiplication distributes over addition. A rig is nearly the same, but we don’t demand additive inverses. A 2-rig is a categorification of rigs, where we give a category a notion of addition and multiplication which obeys a distributive law. The thing which corresponds to addition is the existence of all small colimits, and the thing which corresponds to multiplication is a symmetric monoidal structure.


I think the word “2-rig” was first used in HDAIII.

A 2-rig is a symmetric monoidal cocomplet category for which the monoidal structure preserves small colimits in each argument.