Search results for "torsors"

showing 2 items of 2 documents

Extension theory and the calculus of butterflies

2016

Abstract This paper provides a unified treatment of two distinct viewpoints concerning the classification of group extensions: the first uses weak monoidal functors, the second classifies extensions by means of suitable H 2 -actions. We develop our theory formally, by making explicit a connection between (non-abelian) G-torsors and fibrations. Then we apply our general framework to the classification of extensions in a semi-abelian context, by means of butterflies [1] between internal crossed modules. As a main result, we get an internal version of Dedecker's theorem on the classification of extensions of a group by a crossed module. In the semi-abelian context, Bourn's intrinsic Schreier–M…

TorsorCrossed moduleContext (language use)01 natural sciencesCohomologyCohomology; Extension; Fibrations; Obstruction theory; Schreier-mac lane theorem; TorsorsExtensionMathematics::Category Theory0103 physical sciences0101 mathematicsConnection (algebraic framework)MathematicsAlgebra and Number TheoryFunctorGroup (mathematics)010102 general mathematicsTorsorsExtension (predicate logic)Obstruction theorySchreier-mac lane theoremCohomologyFibrationsAlgebraSettore MAT/02 - AlgebraSchreier–Mac Lane theoremSettore MAT/03 - Geometria010307 mathematical physicsObstruction theory
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A survey on algebraic dilatations

2023

In this text, we wish to provide the reader with a short guide to recent works on the theory of dilatations in Commutative Algebra and Algebraic Geometry. These works fall naturally into two categories: one emphasises foundational and theoretical aspects and the other applications to existing theories.

torsorsaffine modificationsdifferential Galois groupsformal blowupsNéron blowups[MATH] Mathematics [math]Commutative Algebra (math.AC)shtukasMathematics - Algebraic Geometryaffine blowupsFOS: Mathematicsalgebraic dilatations[MATH]Mathematics [math]Algebraic Geometry (math.AG)multi-centered dilatationsdilatations of schemesA 1 -homotopy theoryKaliman-Zaidenberg modificationslevel structuresMoy-Prasad isomorphismrepresentations of p-adic groupsMathematics - Commutative Algebramono-centered dilatationslocalizations of ringscongruent isomorphismsTannakian groupsaffine geometry
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