Partial and free weakly associative lattices
Ervin Fried, George Grätzer · 1976
(A;^,v) with two binary operations satisfying the following identities (this set is redundant, e.g.,(I) can be omitted): (I) x ^ x = x and x v x = x (idempotency) (C) x ^ y = y ^ x and xv y = y v x (commutativity)