[_____] GROUP REPRESENTATIONS  
Acknowledgements
 
Introduction
      Definitions and Background
      Categories
 
Creation of Group Representations
      General Group Representations
      Subrepresentations
      Natural Representations
      New Representations from Old
      New Combinatorially Free Modules from Old
      Highest Weight Representations
      Creation of Combinatorial Free Modules
 
Basic Properties
      Accessing Representation Information
      Accessing Combinatorial Free Module Information
      Predicates
 
Operations on Group Representations
      Base Change
      Other Operations
 
Elements of Group Representations
      Creation of Elements
      Basic Properties
      Operations on Elements
      Comparisons and Membership
      Other Operations
 
Homomorphisms of Group Representations
      Creation of Homomorphisms between Group Representations
      Properties of Homomorphisms of Group Representations
      Operations on Homomorphisms of Group Representations
 
Bibliography







 
Introduction

      Definitions and Background

      Categories

 
Creation of Group Representations

      General Group Representations
            GroupRepresentation(G, M, action) : Grp, CombFreeMod, MonStgElt -> ModRed

      Subrepresentations
            Subrepresentation(V, t) : ModRed, Any -> ModRed, ModRedHom

      Natural Representations
            TrivialRepresentation(G, R) : Grp, Rng -> ModRed
            StandardRepresentation(G) : GrpMat -> ModRed
            SpinorNormRepresentation(G, d) : GrpRed, RngIntElt -> ModRed
            Rho(G, k, j) : GrpMat, RngIntElt, RngIntElt -> ModRed
            SymSpinor(G, d, k) : GrpRed, RngIntElt, RngIntElt -> ModRed
            AltSpinor(G, d) : GrpRed, RngIntElt, RngIntElt -> ModRed
            RadicalSignCharacterSinglePrime(G, p) : GrpRed, RngIntElt -> ModRed
            RadicalSignCharacter(G, d) : GrpRed, RngIntElt -> ModRed
            SpinRepresentation(G, p) : GrpRed, RngIntElt -> ModRed

      New Representations from Old
            DeterminantRepresentation(G) : GrpMat -> ModRed
            SymmetricRepresentation(V, n) : ModRed, RngIntElt -> ModRed
            AlternatingRepresentation(V, n) : ModRed, RngIntElt -> ModRed
            DualRepresentation(V) : ModRed -> ModRed
            TensorProduct(V, W) : ModRed, ModRed -> ModRed
            TensorPower(V, d) : ModRed, RngIntElt -> ModRed
            Pullback(V, f, G) : ModRed, MonStgElt, Grp -> ModRed

      New Combinatorially Free Modules from Old
            ExteriorPower(M, n) : CombFreeMod, RngIntElt -> CombFreeMod
            ExteriorAlgebra(M) : CombFreeMod -> CombFreeMod, CombFreeModHom
            DirectSum(M) : [ CombFreeMod ] -> CombFreeMod

      Highest Weight Representations
            GroupRepresentation(G, w) : GrpLie, [ RngIntElt ] -> ModRed
            HighestWeightRepresentation(G, w) : GrpRed, [ RngIntElt ] -> ModRed
            HighestWeightRepresentation(G, w, p) : GrpRed, [ RngIntElt ], RngIntElt -> ModRed

      Creation of Combinatorial Free Modules
            CombinatorialFreeModule(R, S) : Rng, SetIndx -> CombFreeMod

 
Basic Properties

      Accessing Representation Information
            Rank(V) : ModRed -> RngIntElt
            Basis(V) :ModRed -> [ ModRedElt ]
            BaseRing(V) : ModRed -> Rng
            Group(V) : ModRed -> Grp
            CFM(V) : ModRed -> CombFreeMod

      Accessing Combinatorial Free Module Information
            Rank(M) : CombFreeMod -> RngIntElt
            Basis(M) : CombFreeMod -> [ CombFreeModElt ]
            BaseRing(M) : CombFreeMod -> Rng
            Names(M) : CombFreeMod -> SetIndx

      Predicates
            IsTrivial(V) : ModRed -> BoolElt

 
Operations on Group Representations
      Intersection(V, W) : ModRed, ModRed -> ModRed
      V eq W : ModRed, ModRed -> BoolElt

      Base Change
            ChangeRing(V, S) : ModRed, Rng -> ModRed
            ChangeRing(M, S) : CombFreeMod, Rng -> CombFreeMod

      Other Operations
            FixedSubspace(H, V) : GrpMat, ModRed -> ModRed

 
Elements of Group Representations

      Creation of Elements
            GroupRepresentationElement(V, m) : ModRed, CombFreeModElt -> ModRedElt
            CombinatorialFreeModuleElement(M, v) : CombFreeMod, ModRngElt -> CombFreeModElt

      Basic Properties
            Parent(v) : ModRedElt -> ModRed
            ActionMatrix(V, g) : ModRed, GrpElt -> GrpMatElt

      Operations on Elements
            v + w : ModRedElt, ModRedElt -> ModRedElt
            v - w : ModRedElt, ModRedElt -> ModRedElt
            a * v : RngElt, ModRedElt -> ModRedElt
            g * v : GrpElt, ModRedElt -> ModRedElt
            m * v : AlgMatElt, ModRedElt -> ModRedElt
            v ^ w : CombFreeModElt, CombFreeModElt -> CombFreeModElt

      Comparisons and Membership
            v eq w : ModRedElt, ModRedElt -> BoolElt
            v in V : ModRedElt, ModRed -> BoolElt

      Other Operations
            Eltseq(v) : ModRedElt -> []
            ChangeRing(v, S) : CombFreeModElt, Rng -> CombFreeModElt

 
Homomorphisms of Group Representations

      Creation of Homomorphisms between Group Representations
            Homomorphism(V, W, f) : ModRed, ModRed, UserProgram -> ModRedHom
            Homomorphism(V, W, S) : ModRed, ModRed, SeqEnum -> ModRedHom
            Homomorphism(M, N, f) : CombFreeMod, CombFreeMod, UserProgram -> CombFreeModHom
            Homomorphism(M, N, S) : CombFreeMod, CombFreeMod, SeqEnum -> CombFreeModHom

      Properties of Homomorphisms of Group Representations
            Domain(f) : ModRedHom -> ModRed
            Codomain(f) : ModRedHom -> ModRed
            Kernel(f) : ModRedHom -> ModRed

      Operations on Homomorphisms of Group Representations
            Evaluate(f, v) : ModRedHom, ModRedElt -> ModRedElt
            w @@ f : ModRedElt, ModRedHom -> ModRedElt

 
Bibliography

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Version: V2.29 of Fri Nov 28 15:14:01 AEDT 2025