equational logic
First-order equational logic consists of
{quantifier}-free terms of ordinary {first-order logic}, with
equality as the only {predicate} symbol. The {model theory}
of this logic was developed into {Universal algebra} by
Birkhoff et al. [Birkhoff, Gratzer, Cohn]. It was later made
into a branch of {category theory} by Lawvere ("algebraic
theories").
(1995-02-21)