17A30 08B20 6 semigroup 5 20M10 4 20M50 4 doppelsemigroup 3 08A30 2 08A35 2 17D99 2 congruence 2 dimonoid 2 endomorphism semigroup 2 interassociativity 2 strong doppelsemigroup 2 06F05 1 43A65 1 \(n\)-tuple semigroup 1 abelian dimonoid 1 automorphism 1 binary relation 1 free \(n\)-tuple semigroup 1 free abelian diband 1 free abelian dimonoid 1 free trioid 1 ordered doppelsemigroup 1 relatively free \(n\)-tuple semigroup 1 representation 1 trioid 1