Subvariety

Summary

A subvariety of a variety $\mathcal{V}$ is a variety of the same signature that is contained in $\mathcal{V}$. It is obtained from $\mathcal{V}$ by adding more identities. Abelian groups form a subvariety of groups, and distributive lattices form a subvariety of lattices. The subvarieties of a variety form a lattice, which organises the classification of varieties.