$\mathscr Q$-Sets and Friends: Regarding Singleton and Gluing Completeness

Abstract

This work is largely focused on extending D. Higgs' $\Omega$-sets to the context of quantales, following the broad program of U. H\"ohle, we explore the rich category of $\mathscr Q$-sets for strong, integral and commutative quantales, or other similar axioms. The focus of this work is to study the different notion of 'completeness' a $\mathscr Q$-set may enjoy and their relations, completion functors, resulting reflective subcategories, their relations to relational morphisms. We establish the general equivalence of singleton complete $\mathscr Q$-sets with functional morphisms and the category of $\mathscr Q$-sets with relational morphisms; we provide two characterizations of singleton completeness in categorical terms; we show that the singleton complete categorical inclusion creates limits.