Category of rings (source code)

= Category of rings
{title2=$\mathbf{Rng}$}

The category of unital <rings> has identity-preserving <ring homomorphisms> as morphisms. The zero ring, allowing $0=1$, is terminal, and $\mathbb Z$ is initial. Nonzero rings admit no maps from the zero ring. Monomorphisms are injective: maps from $\mathbb Z[x]$ probe individual elements. It is a <regular category>, with surjective homomorphisms as <regular epimorphisms>; these are distinct from arbitrary categorical <epimorphisms>.