This paper applies the concept of FA-presentable structures to semigroups. We give a complete classification of the finitely generated FA-presentable cancellative semigroups: namely, a finitely generated cancellative semigroup is FA-presentable if and only if it is a subsemigroup of a virtually abelian group. We prove that all finitely generated commutative semigroups are FA-presentable. We giv...

Cancellations are known to be helpful in e cient algebraic computation of polynomials over elds. We de ne a notion of cancellation in Boolean circuits and de ne Boolean circuits that do not use cancellation to be non-cancellative. Non-cancellative Boolean circuits are a natural generalization of monotone Boolean circuits. We show that in the absence of cancellation, Boolean circuits require sup...

Every cancellative Kleene semigroup satisfies Eilenberg's theorem. Résumé. — Si S est un semigroupe simplifiable de type Kleene, alors S satisfait le théorème d'Eilenberg.

Cancellative dimer algebras on a torus have many nice algebraic and homological properties. However, these properties disappear for higher genus surfaces. We consider new class of quiver surfaces, called 'geodesic ghor algebras', that reduce to cancellative torus, yet continue These exhibit rich interplay between their central geometry the topology surface. show (nontrivial) geodesic do in fact...

The following problem is considered: when can the action of a cancellative semigroup S on a set be extended to a simply transitive action of the universal group of S on a larger set.