A band is a semigroup B = (B,·) such that · is idempotent: xx = x.
Let B and C be bands. A morphism from B to C is a function h : B→C that is a homomorphism: h(xy) = h(x)h(y).
|Equational theory||decidable in polynomial time|
|Congruence extension property||no|
|Definable principal congruences|
|Equationally definable principal congruences|
|Strong amalgamation property||no|
|Epimorphisms are surjective|