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INVARIANT RINGS OF FINITE GROUPS

 
Introduction
 
Creation of Invariant Rings
 
Accessing Invariant Rings
 
Group Actions on Polynomials
      Permutation Group Actions on Polynomials
      Matrix Group Actions on Polynomials
 
Construction of G-modules
 
Verbosity
 
Construction of Invariants of Specified Degree
 
Molien Series
 
Primary Invariants
 
Secondary Invariants
 
Fundamental Invariants
 
The Module of an Invariant Ring
 
The Algebra of an Invariant Ring and Algebraic Relations
 
Properties of Invariant Rings
 
Steenrod Operations
 
Minimalization and Homogeneous Module Testing
 
Attributes of Invariant Rings
 
Bibliography







DETAILS

 
Introduction

 
Creation of Invariant Rings
      InvariantRing(G) : GrpMat -> RngInvar

 
Accessing Invariant Rings
      Group(R) : RngInvar -> Grp
      CoefficientRing(R) : RngInvar -> Grp
      PolynomialRing(R) : RngInvar -> RngMPol
      f in R : RngMPol, RngInvar -> FldFunUElt, ModMPolElt

 
Group Actions on Polynomials

      Permutation Group Actions on Polynomials
            f ^ g : RngMPolElt, GrpPermElt -> RngMPolElt
            f ^ G : RngMPolElt, GrpPerm -> { RngMPolElt }
            IsInvariant(f, g) : RngMPolElt, GrpElt -> BoolElt
            IsInvariant(f, G) : RngMPolElt, Grp -> BoolElt

      Matrix Group Actions on Polynomials
            f ^ a : RngMPolElt, GrpMatElt -> RngMPolElt
            f ^ G : RngMPolElt, GrpMat -> { RngMPolElt }
            Example RngInvar_GroupActions (H78E1)

 
Construction of G-modules
      GModule(G, P, d) : Grp, RngMPol, RngIntElt -> ModGrp, Map, @ RngMPolElt @
      GModule(G, I, J) : Grp, RngMPol, RngMPol -> ModGrp, Map, @ RngMPolElt @
      GModule(G, Q) : Grp, RngMPolRes -> ModGrp, Map, @ RngMPolElt @
      Example RngInvar_GModule (H78E2)

 
Verbosity
      SetVerbose("Invariants", v) : MonStgElt, RngIntElt ->

 
Construction of Invariants of Specified Degree
      ReynoldsOperator(f, G) : RngMPolElt, GrpMat -> RngMPolElt
      InvariantsOfDegree(R, d) : RngInvar, RngIntElt -> [ RngMPolElt ]
      InvariantsOfDegree(R, d, k) : RngInvar, RngIntElt, RngIntElt -> [ RngMPolElt ]
      Example RngInvar_InvariantsOfDegree (H78E3)
      SetAllInvariantsOfDegree(R, d, Q) : RngInvar, RngIntElt, [ RngMPolElt ] ->
      Example RngInvar_InvariantsOfDegree (H78E4)

 
Molien Series
      MolienSeries(G) : GrpMat -> FldFunUElt
      Example RngInvar_MolienSeries (H78E5)

 
Primary Invariants
      PrimaryInvariants(R) : RngInvar -> [ RngMPolElt ]
      Example RngInvar_AdemMilgram (H78E6)

 
Secondary Invariants
      SecondaryInvariants(R) : RngInvar -> [ RngMPolElt ]
      SecondaryInvariants(R, H) : RngInvar, Grp -> [ RngMPolElt ]
      IrreducibleSecondaryInvariants(R) : RngInvar -> [ RngMPolElt ]
      Example RngInvar_SecondaryInvariants (H78E7)

 
Fundamental Invariants
      FundamentalInvariants(R) : RngInvar -> [ RngMPolElt ]
      Example RngInvar_FundamentalInvariants (H78E8)

 
The Module of an Invariant Ring
      Module(R) : RngInvar -> ModMPol, Map
      Example RngInvar_Module (H78E9)

 
The Algebra of an Invariant Ring and Algebraic Relations
      Algebra(R) : RngInvar -> RngMPol, [ RngMPolElt ]
      Relations(R) : RngInvar -> [ RngMPolElt ]
      RelationIdeal(R) : RngInvar -> RngMPol
      PrimaryAlgebra(R) : RngInvar -> RngMPol
      PrimaryIdeal(R) : RngInvar -> RngMPol
      Example RngInvar_Relations (H78E10)

 
Properties of Invariant Rings
      HilbertSeries(R) : RngInvar -> FldFunUElt
      IsCohenMacaulay(R) : RngInvar -> BoolElt
      FreeResolution(R) : RngInvar -> [ ModMPol ]
      MinimalFreeResolution(M) : ModMPol -> [ ModMPol ]
      HomologicalDimension(M) : ModMPol -> RngInt
      Depth(R) : RngInvar -> RngIntElt
      Example RngInvar_Depth (H78E11)

 
Steenrod Operations
      SteenrodOperation(f, i) : RngMPolElt, RngIntElt -> RngMPolElt
      Example RngInvar_SteenrodOperation (H78E12)

 
Minimalization and Homogeneous Module Testing
      MinimalAlgebraGenerators(L) : [ RngMPol ] -> [ RngMPol ]
      HomogeneousModuleTest(P, S, F) : [ RngMPol ], [ RngMPol ], RngMPol -> BoolElt, [ RngMPol ]
      HomogeneousModuleTest(P, S, L) : [ RngMPol ], [ RngMPol ], [ RngMPol ] -> [ BoolElt ], [ [ RngMPol ] ]
      Example RngInvar_MinimalAlgebraGenerators (H78E13)
      Example RngInvar_HomogeneousModuleTest2 (H78E14)

 
Attributes of Invariant Rings
      R`PrimaryInvariants
      R`SecondaryInvariants
      R`HilbertSeries

 
Bibliography