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@BartoszMilewski@mathstodon.xyz

Post #2397683

2026-04-24 11:26 UTC

I decided to popularize double categories using profunctor equipment as a model. https://bartoszmilewski.com/2026/04/24/profunctor-equipment/

Replies (3)

  • @sjoerd_visscher@types.pl 2026-04-24 12:20

    @BartoszMilewski@mathstodon.xyz This is awesome! I'm very much in the same boat. Although I decided to limit myself to proarrow equipments only. That's why I have been working on my #haskell proarrow library for the last two years: https://github.com/sjoerdvisscher/proarrow In my case using double categories turned out to be annoying, so I switched to working with a single bicategory of proarrows, seeing the strict arrows as a sub-bicategory of tight/representable proarrows: https://github.com/sjoerdvisscher/proarrow/blob/main/src/Proarrow/Category/Equipment.hs But the double categorical view is better for diagrammatic reasoning.

    Open ##3023671

  • @varkor@mathstodon.xyz 2026-04-24 13:46

    @BartoszMilewski@mathstodon.xyz A quick comment: there is no double category of double categories, because distributors between double categories do not compose. (There is, however, a virtual double category of double categories.)

    Open ##3023675

  • @sjoerd_visscher@types.pl 2026-04-27 14:46

    @BartoszMilewski@mathstodon.xyz Just realized you also might be interested in this post: https://types.pl/@sjoerd_visscher/114881107578007749

    Open ##3023679