Each (function f:X→Y) in Set (the large 1-category of small sets)
generates (the following diagram of categories and functors) in CAT (the very large 2-category of large categories).
Note: below (the diagram in CAT) we show (the function f:X→Y in Set) that generates it.
Set↓X∑f=f!→f⋆←∏f=f⋆→Set↓Yfunctors between categories of oversetsσX↓⊣↑iXσY↓⊣↑iYreflections of oversets (supersets) into subsetsSub(X)∃f=f!→f−1←∀f=f⋆→Sub(Y)order-preserving maps between posets of subsetsX→fYan arrow (function) in Set
Each horizontal triple of arrows, upper and lower, is an adjoint triple, i.e. an adjoint string of length 3.
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