Implication Details

Claim: If a category has a subobject classifier, then it is finitely complete and is mono-regular.

Proof: The first part holds by convention, and the second part: any monomorphism U→XU \to X is the equalizer of χU,χX:X⇉Ω\chi_U,\chi_X : X \rightrightarrows \Omega.

This implication has a dual.

Show 84 categories using this implication