categorical question

[Ichthus77 (Ichthus77 (formerly She™))]

@Ichthus77

If “hypothetical (empty) category lacks existential import” is also found in set theory with the empty set, is there a square (hexagon, whatever) of opposition for set theory also, or can one construct one to show synonymous terms between set theory/logic & category theory/logic? Please.

i don’t know
en.m.wikipedia.org/wiki/Monoid