2012/11/04 by Francesco Ciraulo, Ciraulo, Francesco, Maria Emilia Maietti +3
Computer Science · Mathematics · #03F65 #06B23 #06D22 #06F07 #18B35 #54A05 #Advanced Topology and Set Theory #FOS: Mathematics #Homotopy and Cohomology in Algebraic Topology #Logic (math.LO) #Logic, programming, and type systems #math.LO #msc:03F65 #msc:06B23 #msc:06D22 #msc:06F07 #msc:18B35 #msc:54A05
paper · pdf · doi:10.48550/arxiv.1211.0720
arxiv created 2012/11/04 · openalex publication_date 2012/11/04 · arxiv updated 2012/11/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Several variations on the definition of a Formal Topology exist in the literature. They differ on how they express convergence, the formal property corresponding to the fact that open subsets are closed under finite intersections. We introduce a general notion of convergence of which any previous definition is a special case. This leads to a predicative presentation and inductive generation of locales (formal covers), commutative quantales (convergent covers) and suplattices (basic covers) in a uniform way. Thanks to our abstract treatment of convergence, we are able to specify categorically the precise sense according to which our inductively generated structures are free, thus refining Johnstone's coverage theorem. We also obtain a natural and predicative version of a fundamental result by Joyal and Tierney: convergent covers (commutative quantales) correspond to commutative co-semigroups over the category of basic covers (suplattices).