O conjunto de Buchweitz de um semigrupo numérico

Abstract

Given a non-singular algebraic curve defined over an algebraically closed field, it is possible to associate each point on that curve with a numerical semigroup that has the same genus as the curve. Given a numerical semigroup S, a necessary condition for the existence of a non-singular algebraic curve defined over an algebraically closed field and a point on that curve whose associated numerical semigroup is exactly S is that a certain subset of the naturals related to the set of gaps in S is empty. This subset is called the Buchweitz set of S. In the first chapter of this master’s thesis, we present a study on numerical semigroups and their invariants with the aim of having tools to study the Buchweitz set of a numerical semigroup. In particular, we want to study its finiteness, as a step towards studying when it is empty. Furthermore, we show that, despite being finite when g ≥ 2, the cardinality of these sets is not limited.