Implication Details

Claim: If a category has binary products and has equalizers, then it has pullbacks.

Proof: The pullback of f:X→Sf : X \to S and g:Y→Sg : Y \to S is the equalizer of f∘p1, g∘p2:X×Y⇉Sf \circ p_1, \, g \circ p_2 : X \times Y \rightrightarrows S.

This implication has a dual.

Show 47 categories using this implication