Search results for "Automorphisms"

showing 10 items of 24 documents

Irreducible components of Hurwitz spaces of coverings with two special fibers

2013

In this paper we prove new results of irreducibility for Hurwitz spaces of coverings whose monodromy group is a Weyl group of type B_d and whose local monodromies are all reflections except two.

Weyl groupPure mathematicsHurwitz quaternionGroup (mathematics)General MathematicsType (model theory)Hurwitz spaces special fibers branched coverings Weyl group of type B_d monodromy braid moves.symbols.namesakeMathematics::Algebraic GeometryMonodromyHurwitz's automorphisms theoremsymbolsIrreducibilitySettore MAT/03 - GeometriaMathematics::Representation TheoryMathematics
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ON AUTOMORPHISMS OF GENERALIZED ALGEBRAIC-GEOMETRY CODES.

2007

Abstract We consider a class of generalized algebraic-geometry codes based on places of the same degree of a fixed algebraic function field over a finite field F / F q . We study automorphisms of such codes which are associated with automorphisms of F / F q .

Algebraic function fieldDiscrete mathematicsAlgebraic cycleFinite fieldFunction field of an algebraic varietyAlgebra and Number TheoryAutomorphisms of the symmetric and alternating groupsAlgebraic extensionAlgebraic geometryAutomorphismMathematics
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Unbounded derivations and *-automorphisms groups of Banach quasi *-algebras

2018

This paper is devoted to the study of unbounded derivations on Banach quasi *-algebras with a particular emphasis to the case when they are infinitesimal generators of one parameter automorphisms groups. Both of them, derivations and automorphisms are considered in a weak sense; i.e., with the use of a certain families of bounded sesquilinear forms. Conditions for a weak *-derivation to be the generator of a *-automorphisms group are given.

Unbounded derivationPure mathematicsAutomorphisms groups and their infinitesimal generatorsInfinitesimalBanach quasi *-algebra01 natural sciencesMathematics::Group Theory*-Automorphisms groups and their infinitesimal generatorSettore MAT/05 - Analisi Matematica0103 physical sciencesFOS: MathematicsAutomorphisms groups and their infinitesimal generators; Banach quasi; Integrability of derivation; Unbounded derivations; Automorphisms groups and their infinitesimal generators; Banach quasi; Integrability of derivation; Unbounded derivationsBanach quasi0101 mathematicsOperator Algebras (math.OA)MathematicsGroup (mathematics)Applied Mathematics010102 general mathematicsIntegrability of derivationMathematics - Operator AlgebrasAutomorphismUnbounded derivationsFunctional Analysis (math.FA)Mathematics - Functional AnalysisBounded function010307 mathematical physicsGenerator (mathematics)
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Transitive factorizations in the hyperoctahedral group

2008

The classical Hurwitz enumeration problem has a presentation in terms of transitive factor- izationsin the symmetric group. This presentationsuggestsageneralizationfromtypeAto otherfinite reflection groups and, in particular, to type B.W e study this generalization both from ac ombinatorial and a geometric point of view, with the prospect of providing am eans of understanding more of the structure of the moduli spaces of maps with an S2-symmetry. The type A case has been well studied and connects Hurwitz numbers to the moduli space of curves. W ec onjecture an analogous setting for the type B case that is studied here. 1I ntroduction Transitive factorizations of permutations into transposit…

CombinatoricsAlgebraic combinatoricsHurwitz quaternionHurwitz problemSymmetric groupGeneral MathematicsHurwitz's automorphisms theoremHurwitz matrixHurwitz polynomialSettore MAT/03 - GeometriaHyperoctahedral groupMathematicssymmetric group covering space
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Automorphisms of the integral group ring of the hyperoctahedral group

1990

The purpose of this paper is to verify a conjecture of Zassenhaus [3] for hyperoctahedral groups by proving that every normalized automorphism () of ZG can be written in the form () = Tu 0 I where I is an automorphism of ZG obtained by extending an automorphism of G linearly to ZG and u is a unit of (JJG. A similar result was proved for symmetric groups by Peterson in [2]; the reader should consult [3] or the survey [4] for other results of this kind. 1989

CombinatoricsAlgebra and Number TheoryMatrix groupSymmetric groupAutomorphisms of the symmetric and alternating groupsOuter automorphism groupAlternating groupHyperoctahedral groupTopologyAutomorphismMathematicsGroup ringCommunications in Algebra
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Hurwitz spaces of Galois coverings of P1, whose Galois groups are Weyl groups

2006

Abstract We prove the irreducibility of the Hurwitz spaces which parametrize equivalence classes of Galois coverings of P 1 , whose Galois group is an arbitrary Weyl group, and the local monodromies are reflections. This generalizes a classical theorem due to Luroth, Clebsch and Hurwitz.

Discrete mathematicsPure mathematicsAlgebra and Number TheoryGalois cohomologyMathematics::Number TheoryFundamental theorem of Galois theoryGalois groupGalois moduleDifferential Galois theoryEmbedding problemsymbols.namesakeMathematics::Algebraic GeometryHurwitz's automorphisms theoremsymbolsGalois extensionMathematicsJournal of Algebra
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A note on endomorphisms of hypercentral groups

2002

Abstract Let H be a subnormal subgroup of a hypercentral group G. We prove that endomorphisms of G are uniquely determined by their restrictions to H if and only if Hom(G/HG,G)=0, and draw some consequences from this fact.

Discrete mathematicsSubnormal subgroupAutomorphisms and endomorphisms of groupsPure mathematicsAlgebra and Number TheoryEndomorphismIf and only ifGroup (mathematics)Nilpotent and hypercentral groupsMathematicsJournal of Algebra
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Locally tame plane polynomial automorphisms

2010

Abstract For automorphisms of a polynomial ring in two variables over a domain R , we show that local tameness implies global tameness provided that every 2-generated locally free R -module of rank 1 is free. We give examples illustrating this property.

PolynomialRank (linear algebra)Polynomial ringPolynomial automorphismsCommutative Algebra (math.AC)01 natural sciencesCombinatoricsMathematics - Algebraic GeometryFOS: MathematicsAlgebra en Topologie0101 mathematicsAlgebraic Geometry (math.AG)MathematicsAlgebra and TopologyAlgebra and Number TheoryPlane (geometry)local tameness010102 general mathematicsA domainMathematics - Commutative AlgebraAutomorphism[ MATH.MATH-AG ] Mathematics [math]/Algebraic Geometry [math.AG]010101 applied mathematicsComputingMethodologies_DOCUMENTANDTEXTPROCESSING[MATH.MATH-AG]Mathematics [math]/Algebraic Geometry [math.AG]14R10Journal of Pure and Applied Algebra
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Quotients of the Dwork Pencil

2012

In this paper we investigate the geometry of the Dwork pencil in any dimension. More specifically, we study the automorphism group G of the generic fiber of the pencil over the complex projective line, and the quotients of it by various subgroups of G. In particular, we compute the Hodge numbers of these quotients via orbifold cohomology.

Automorphism groupPure mathematicsAutomorphismsDwork pencilGeneral Physics and AstronomyAutomorphismCalabi–Yau manifoldCohomologyAlgebraMathematics - Algebraic GeometryMathematics::Algebraic GeometryProjective lineFOS: MathematicsSettore MAT/03 - GeometriaGeometry and TopologyMathematics::Symplectic GeometryAlgebraic Geometry (math.AG)Mathematical PhysicsOrbifoldPencil (mathematics)QuotientMathematics
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Irreducibility of Hurwitz spaces of coverings with one special fiber

2006

Abstract Let Y be a smooth, projective complex curve of genus g ⩾ 1. Let d be an integer ⩾ 3, let e = {e1, e2,..., er} be a partition of d and let | e | = Σi=1r(ei − 1). In this paper we study the Hurwitz spaces which parametrize coverings of degree d of Y branched in n points of which n − 1 are points of simple ramification and one is a special point whose local monodromy has cyclic type e and furthermore the coverings have full monodromy group Sd. We prove the irreducibility of these Hurwitz spaces when n − 1 + | e | ⩾ 2d, thus generalizing a result of Graber, Harris and Starr [A note on Hurwitz schemes of covers of a positive genus curve, Preprint, math. AG/0205056].

AlgebraCombinatoricsHurwitz spaceBundleMathematics(all)Mathematics::Algebraic GeometryMonodromyGeneral MathematicsHurwitz's automorphisms theoremIrreducibilityPartition (number theory)local monodromiesMathematicsIndagationes Mathematicae
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