Post #3023675
2026-04-24 13:46 UTC
@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.)
Replies (1)
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@BartoszMilewski@mathstodon.xyz 2026-04-24 14:08
@varkor@mathstodon.xyz Thanks, I'll correct this. It was the result of my perusing Grandis & Pare, where they say "the (strict) double category Dbl consisting of weak double categories, lax double functors (as horizontal arrows) and colax double functors (as vertical arrows), with suitable cells." So this works for pseudo or weak double categories.