In this article we prove the following: A topos with a point is connected atomic if and only if it is the classifying topos of a localic group, and this group can be taken to be the locale of automorphisms of the point. We explain and give the necessary definitions to understand this statement. The hard direction in this equivalence was first proved in print in [4], Theorem 1, Section 3, Chapte...

We consider locales B as algebras in the tensor category s` of sup-lattices. We show the equivalence between the Joyal-Tierney descent theorem for open localic surjections shB q −→ E in Galois theory and a Tannakian recognition theorem over s` for the s`-functor Rel(E) Rel(q ∗) −→ Rel(shB) ∼= (B-Mod)0 into the s`-category of discrete B-modules. Thus, a new Tannaka recognition theorem is obtaine...

We give a constructive characterization of morphisms between open sublocales of localic completions of locally compact metric (LCM) spaces, in terms of continuous functions. The category of open subspaces of LCM spaces is thereby shown to embed fully faithfully into the category of locales (or formal topologies). 2000 Mathematics Subject Classification 03F60, 18B30, 54E99 (primary)

LoA) and τ is a subalgebra of A . Morphisms (X,A, τ) (f,φ) −−−→ (Y,B, σ) are Set × LoA-morphisms (X,A) (f,φ) −−−→ (Y,B) such that φ ◦ p ◦ f ∈ τ for every p ∈ σ (the so-called continuity). Our definition subsumes the traditional latticevalued approach of [2]. The motivation for the new concept was provided by the problem of doing fuzzy mathematics without order. In [1] the authors consider a rel...