Almost all minimal idempotent varieties are congruence modular
It is shown that the only minimal idempotent varieties that are not congruence modular are the variety of sets and the variety of semilattices. Applying the machinery of Commutator Theory, we get that a minimal idempotent variety that is not congruence distributive is term-equivalent to the variety of sets, the variety of semilattices, or a variety of affine modules over a simple ring.
scientific article; zbMATH DE number 1899949