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FINITELY PRESENTED ABELIAN GROUPS

 
Acknowledgements
 
Introduction
 
Construction of a Free Abelian Group and its Elements
      Structure Constructors
      Construction of an Element
      Deconstruction of an Element
 
Arithmetic with Elements
      Addition and Subtraction
      Relations
 
Construction of Subgroups and Quotient Groups
      Construction of Subgroups
      Construction of Quotient Groups
 
Specification of a Presentation
      Accessing the Defining Generators and Relations
 
Standard Constructions and Conversions
 
Operations on Elements
      Order of an Element
      Equality and Comparison
 
Invariants of an Abelian Group
 
Canonical Decomposition
 
Set-Theoretic Operations
      Functions Relating to Group Order
      Membership and Equality
      Set Operations
 
Coset Spaces
 
The Subgroup Structure
 
General Group Properties
      General Properties of Subgroups
      Coercions Between Groups and Subgroups
 
Normal Structure and Characteristic Subgroups
      Characteristic Subgroups and Subgroup Series
      Subgroup Structure
 
Conjugacy
 
Representation Theory
 
Computation of Hom
 
Cohomology
 
Bibliography







DETAILS

 
Introduction

 
Construction of a Free Abelian Group and its Elements

      Structure Constructors
            FreeAbelianGroup(n) : RngIntElt -> GrpAb
            Example GrpAb_FreeAbelianGroup (H29E1)

      Construction of an Element
            A ! [a_1, ... ,a_n] : GrpAb, [RngIntElt] -> GrpAbElt
            A ! n : GrpAb, RngIntElt -> GrpAbElt
            Identity(A) : GrpAb -> GrpAbElt

      Deconstruction of an Element
            ElementToSequence(x) : GrpAbElt -> [RngIntElt]

 
Arithmetic with Elements

      Addition and Subtraction
            u + v : GrpAbElt, GrpAbElt -> GrpAbElt
            - u : GrpAbElt -> GrpAbElt
            u - v : GrpAbElt, GrpAbElt -> GrpAbElt
            m * u : RngIntElt, GrpAbElt-> GrpAbElt

      Relations
            w_1 = w_2 : GrpAbElt, GrpAbElt -> Rel
            LHS(r) : Rel -> GrpAbElt
            RHS(r) : Rel -> GrpAbElt
            Parent(r) : GrpAbRel -> GrpAb
            Example GrpAb_Relations (H29E2)

 
Construction of Subgroups and Quotient Groups

      Construction of Subgroups
            sub<A | L> : GrpAb, List -> GrpAb, Map

      Construction of Quotient Groups
            quo<F | R> : GrpAb, List -> GrpAb, Hom(GrpAb)
            A / B : GrpAb, GrpAb -> GrpAb

 
Specification of a Presentation
      AbelianGroup< X | R > : List(Var), List(GrpAbRel) -> GrpAb, Hom(GrpAb)
      Example GrpAb_AbelianGroup (H29E3)

      Accessing the Defining Generators and Relations
            A . i : GrpAb, RngIntElt -> GrpAbElt
            Generators(A) : GrpAb -> { GrpAbElt }
            NumberOfGenerators(A) : GrpAb -> RngIntElt
            Parent(u) : GrpAbElt -> GrpAb
            Relations(A) : GrpAb -> [ Rel ]

 
Standard Constructions and Conversions
      AbelianGroup(GrpAb, Q) : Cat, [ RngIntElt ] -> GrpAb
      AbelianGroup(G) : Grp -> GrpAb, Hom
      AbelianQuotient(G) : Grp -> GrpAb, Hom
      DirectSum(A, B) : GrpAb, GrpAb -> GrpAb
      PCGroup(A) : GrpAb -> GrpPC, Hom(Grp)
      PermutationGroup(A) : GrpAb -> GrpPerm, Hom(Grp)
      FPGroup(A) : GrpAb -> GrpFP, Hom(Grp)

 
Operations on Elements

      Order of an Element
            Order(x) : GrpAbElt -> RngIntElt

      Equality and Comparison
            u eq v : GrpAbElt, GrpAbElt -> BoolElt
            u ne v : GrpAbElt, GrpAbElt -> BoolElt
            IsIdentity(u) : GrpAbElt -> BoolElt

 
Invariants of an Abelian Group
      ElementaryAbelianQuotient(G, p) : GrpAb, RngIntElt -> GrpAb, Map
      FreeAbelianQuotient(G) : GrpAb -> GrpAb, Map
      Invariants(A) : GrpAb -> [ RngIntElt ]
      TorsionFreeRank(A) : GrpAb -> RngIntElt
      TorsionInvariants(A) : GrpAb -> [ RngIntElt ]
      PrimaryInvariants(A) : GrpAb -> [ RngIntElt ]
      pPrimaryInvariants(A, p) : GrpAb, RngIntElt -> [ RngIntElt ]

 
Canonical Decomposition
      TorsionFreeSubgroup(A) : GrpAb -> GrpAb
      TorsionSubgroup(A) : GrpAb -> GrpAb
      pPrimaryComponent(A, p) : GrpAb, RngIntElt -> GrpAb

 
Set-Theoretic Operations

      Functions Relating to Group Order
            Order(G) : GrpAb -> RngIntElt
            FactoredOrder(G) : GrpAb -> [<RngIntElt, RngIntElt>]
            Index(G, H) : GrpAb, GrpAb -> RngIntElt
            FactoredIndex(G, H) : GrpAb, GrpAb -> [<RngIntElt, RngIntElt>]
            Exponent(G) : GrpAb -> RngIntElt
            IsFinite(G) : GrpAb -> BoolElt

      Membership and Equality
            g in G : GrpAbElt, GrpAb -> BoolElt
            g notin G : GrpAbElt, GrpAb -> BoolElt
            S subset G : { GrpAbElt } , GrpAb -> BoolElt
            S notsubset G : { GrpAbElt } , GrpAb -> BoolElt
            H subset G : GrpAb, GrpAb -> BoolElt
            H notsubset G : GrpAb, GrpAb -> BoolElt
            G eq H : GrpAb, GrpAb -> BoolElt
            G ne H : GrpAb, GrpAb -> BoolElt

      Set Operations
            NumberingMap(G) : GrpAb -> Map
            RandomProcess(G) : GrpAb -> Process
            Random(P) : Process -> GrpAbElt
            Random(G) : GrpAb -> GrpAbElt
            Rep(G) : GrpAb -> GrpAbElt

 
Coset Spaces
      Transversal(G, H) : GrpAb, GrpAb -> {@ GrpAbElt @}, Map

 
The Subgroup Structure
      H ^ g : GrpAb, GrpAbElt -> GrpAb
      H ^ G : GrpAb, GrpAb -> GrpAb
      H meet K : GrpAb, GrpAb -> GrpAb
      H meet:= K : GrpAb, GrpAb -> GrpAb
      CommutatorSubgroup(G, H, K) : GrpAb, GrpAb, GrpAb -> GrpAb
      Centralizer(G, g) : GrpAb, GrpAbElt -> GrpAb
      Centralizer(G, H) : GrpAb, GrpAb -> GrpAb
      Core(G, H) : GrpAb, GrpAb -> GrpAb
      NormalClosure(G, H) : GrpAb, GrpAb -> GrpAb
      Normalizer(G, H) : GrpAb, GrpAb -> GrpAb
      SylowSubgroup(G, p) : GrpAb, RngIntElt -> GrpAb
      pCore(G, p) : GrpAb, RngIntElt -> GrpAb

 
General Group Properties
      IsAbelian(G) : GrpAb -> BoolElt
      IsCyclic(G) : GrpAb -> BoolElt
      IsElementaryAbelian(G) : GrpAb -> BoolElt
      IsNilpotent(G) : GrpAb -> BoolElt
      IsPerfect(G) : GrpAb -> BoolElt
      IsSimple(G) : GrpAb -> BoolElt
      IsSoluble(G) : GrpAb -> BoolElt

      General Properties of Subgroups
            IsCentral(G, H) : GrpAb, GrpAb -> BoolElt
            IsConjugate(G, H, K) : GrpAb, GrpAb, GrpAb -> BoolElt, GrpAbElt
            IsMaximal(G, H) : GrpAb, GrpAb -> BoolElt
            IsNormal(G, H) : GrpAb, GrpAb -> BoolElt
            IsSubnormal(G, H) : GrpAb, GrpAb -> BoolElt

      Coercions Between Groups and Subgroups
            G ! g : GrpAb, GrpAbElt -> GrpAbElt
            H ! g : GrpAb, GrpAbElt -> GrpAbElt
            K ! g : GrpAb, GrpAbElt -> GrpAbElt
            Morphism(H, G) : GrpAb, GrpAb -> ModMatRngElt

 
Normal Structure and Characteristic Subgroups

      Characteristic Subgroups and Subgroup Series
            Agemo(G, i) : GrpAb, RngIntElt -> GrpAb
            Centre(G) : GrpAb -> GrpAb
            ChiefSeries(G) : GrpAb -> [GrpAb]
            DerivedLength(G) : GrpAb -> RngIntElt
            DerivedSeries(G) : GrpAb -> [GrpAb]
            DerivedSubgroup(G) : GrpAb -> GrpAb
            ElementaryAbelianSeries(G) : GrpAb -> [GrpAb]
            FittingSubgroup(G) : GrpAb -> GrpAb
            FrattiniSubgroup(G) : GrpAb -> GrpAb
            Hypercentre(G) : GrpAb -> GrpAb
            NilpotencyClass(G) : GrpAb -> RngIntElt
            Omega(G, i) : GrpAb, RngIntElt -> GrpAb
            SubnormalSeries(G, H) : GrpAb, GrpAb -> [GrpAb]
            UpperCentralSeries(G) : GrpAb -> [GrpAb]

      Subgroup Structure
            MaximalSubgroups(G) : GrpAb -> [GrpAb]
            Subgroups(G:parameters) : GrpAb -> [Rec]
            Example GrpAb_Subgroups (H29E4)

 
Conjugacy
      Class(H, g) : GrpAb, GrpAbElt -> { GrpAbElt }
      ConjugacyClasses(G) : GrpAb -> [ <RngIntElt, RngIntElt, GrpAbElt> ]
      ClassMap(G) : GrpAb -> Map
      ClassMatrix(G, i) : GrpAb, RngIntElt -> AlgMatElt
      ClassRepresentative(G, x) : GrpAb, GrpAbElt -> GrpAbElt
      IsConjugate(G, g, h) : GrpAb, GrpAbElt, GrpAbElt -> BoolElt, GrpAbElt
      IsConjugate(G, H, K) : GrpAb, GrpAb, GrpAb -> BoolElt, GrpAbElt
      NumberOfClasses(G) : GrpAb -> RngIntElt
      PowerMap(G) : GrpAb -> Map

 
Representation Theory
      CharacterTable(G) : GrpAb -> TabChtr

 
Computation of Hom
      Hom(G, H) : GrpAb, GrpAb -> GrpAb, Map
      HomGenerators(G, H) : GrpAb, GrpAb -> GrpAb, Map
      Homomorphisms(G, H) : GrpAb, GrpAb -> GrpAb, Map
      Example GrpAb_Relations (H29E5)

 
Cohomology
      Dual(G) : GrpAb -> GrpAb, Map
      H2_G_QmodZ(G) : GrpAb -> GrpAb, Map

 
Bibliography