Coxeter Groups
- Introduction
- Constructing Coxeter Groups
CoxeterGroup(grpcat, N): Cat, MonStgElt → grpcat
CoxeterGroup(N): MonStgElt → Grp
IrreducibleCoxeterGroup(grpcat, X, n): Cat, MonStgElt, RngIntElt → grpcat
IrreducibleCoxeterGroup(X, n): MonStgElt, RngIntElt → .
Example: Construct By Name
CoxeterGroup(grpcat, M): Cat, AlgMatElt → grpcat
CoxeterGroup(grpcat, G): Cat, GrphUnd → grpcat
CoxeterGroup(grpcat, D): Cat, GrphDir → grpcat
CoxeterGroup(M): AlgMatElt → Grp
CoxeterGroup(G): GrphUnd → Grp
CoxeterGroup(D): GrphDir → Grp
Example: Construct From Matrix
CoxeterGroup(grpcat, R): Cat, RootStr → grpcat
CoxeterGroup(R): RootStr → GrpPermCox
CoxeterGroup(A, B): Mtrx, Mtrx → GrpPermCox
CoxeterGroup(grpcat, A, B): Cat, Mtrx, Mtrx → grpcat
Example: Construct By Root
- Converting Between Types of Coxeter Group
- Operations on Coxeter Groups
IsIsomorphic(W1, W2): GrpPermCox, GrpPermCox → BoolElt
IsCoxeterIsomorphic(W1, W2): GrpFPCox, GrpFPCox → BoolElt
IsCoxeterIsomorphic(W1, W2): GrpPermCox, GrpPermCox → BoolElt
IsCartanEquivalent(W1, W2): GrpPermCox, GrpPermCox → BoolElt
Example: Coxeter Isomorphism
RootSystem(W): GrpPermCox → RootDtm
RootDatum(W): GrpPermCox → RootDtm
Example: Group To Root
CartanName(W): GrpFPCox → List
CartanName(W): GrpPermCox → MonStgElt
CoxeterDiagram(W): GrpFPCox
CoxeterDiagram(W): GrpPermCox
DynkinDiagram(W): GrpPermCox
Example: Names Diagrams
CoxeterMatrix(W): GrpFPCox → AlgMatElt
CoxeterMatrix(W): GrpPermCox → AlgMatElt
CoxeterGraph(W): GrpFPCox → GrphUnd
CoxeterGraph(W): GrpPermCox → GrphUnd
CartanMatrix(W): GrpPermCox → AlgMatElt
DynkinDigraph(W): GrpPermCox → GrphDir
Rank(W): GrpFPCox → RngIntElt
Rank(W): GrpPermCox → RngIntElt
NumberOfGenerators(W): GrpFPCox → RngIntElt
NumberOfGenerators(W): GrpPermCox → RngIntElt
NumberOfPositiveRoots(W): GrpFPCox → RngIntElt
NumberOfPositiveRoots(W): GrpPermCox → RngIntElt
NumPosRoots(W): GrpFPCox → RngIntElt
NumPosRoots(W): GrpPermCox → RngIntElt
Dimension(W): GrpPermCox → RngIntElt
Example: Rank Dimension
ConjugacyClasses(W): GrpFPCox → [GrpFPCoxElt]
ConjugacyClasses(W): GrpPermCox → [GrpPermElt]
FundamentalGroup(W): GrpPermCox → GrpAb
IsogenyGroup(W): GrpPermCox → GrpAb
CoisogenyGroup(W): GrpPermCox → GrpAb
BasicDegrees(W): GrpFPCox → RngIntElt
BasicDegrees(W): GrpPermCox → RngIntElt
BasicCodegrees(W): GrpFPCox → RngIntElt
BasicCodegrees(W): GrpPermCox → RngIntElt
Example: Basic Degrees
BruhatLessOrEqual(x, y): GrpPermElt, GrpPermElt → BoolElt
BruhatDescendants(x): GrpPermElt → SetEnum
BruhatDescendants(X): SetEnum → SetEnum
Example: Bruhat Descendants
- Properties of Coxeter Groups
- Operations on Elements
Example: Word Arithmetic
# w: GrpFPCoxElt → RngIntElt
Length(w): GrpFPCoxElt → RngIntElt
Length(W, w): GrpPermCox, GrpPermElt → RngIntElt
CoxeterLength(w): GrpFPCoxElt → RngIntElt
CoxeterLength(W, w): GrpPermCox, GrpPermElt → RngIntElt
LongestElement(W): GrpFPCox → SeqEnum
LongestElement(W): GrpPermCox → GrpPermElt
CoxeterElement(W): GrpFPCox → SeqEnum
CoxeterElement(W): GrpPermCox → GrpPermElt
CoxeterNumber(W): GrpFPCox → SeqEnum
CoxeterNumber(W): GrpPermCox → GrpPermElt
Example: Longest Coxeter Elements
LeftDescentSet(W, w): GrpFPCox, GrpFPCoxElt → SetEnum
LeftDescentSet(W, w): GrpPermCox, GrpPermElt → SetEnum
RightDescentSet(W, w): GrpFPCox, GrpFPCoxElt → SetEnum
RightDescentSet(W, w): GrpPermCox, GrpPermElt → SetEnum
Example: Descent Sets
- Roots, Coroots and Reflections
- Accessing Roots and Coroots
RootSpace(W): GrpPermCox → .
CorootSpace(W): GrpPermCox → .
SimpleRoots(W): GrpPermCox → Mtrx
SimpleCoroots(W): GrpPermCox → Mtrx
Example: Root Space
NumberOfPositiveRoots(W): GrpPermCox → RngIntElt
NumPosRoots(W): GrpPermCox → RngIntElt
Roots(W): GrpPermCox → SetIndx
Coroots(W): GrpPermCox → SetIndx
PositiveRoots(W): GrpPermCox → SetIndx
PositiveCoroots(W): GrpPermCox → SetIndx
Root(W, r): GrpPermCox, RngIntElt → SetIndx
Coroot(W, r): GrpPermCox, RngIntElt → SetIndx
RootPosition(W, v): GrpPermCox, . → SetIndx
CorootPosition(W, v): GrpPermCox, . → SetIndx
Example: Roots Coroots
HighestRoot(W): GrpPermCox → .
HighestLongRoot(W): GrpPermCox → .
HighestShortRoot(W): GrpPermCox → .
Example: Heighest Roots
CoxeterForm(W): GrpPermCox → AlgMatElt
DualCoxeterForm(W): GrpPermCox → AlgMatElt
AdditiveOrder(W): GrpPermCox → SeqEnum
PapiOrder(W,w): GrpPermCox, GrpPermElt → SeqEnum
PapiOrder(W, wd): GrpPermCox, SeqEnum[RngIntElt] → SeqEnum
- Operations and Properties for Root and Coroot Indices
Sum(W, r, s): GrpPermCox, RngIntElt, RngIntElt → RngIntElt
IsPositive(W, r): GrpPermCox, RngIntElt → BoolElt
IsNegative(W, r): GrpPermCox, RngIntElt → BoolElt
Negative(W, r): GrpPermCox, RngIntElt → RngIntElt
LeftString(W, r, s): GrpPermCox, RngIntElt, RngIntElt → RngIntElt
RightString(W, r, s): GrpPermCox, RngIntElt, RngIntElt → RngIntElt
LeftStringLength(W, r, s): GrpPermCox, RngIntElt, RngIntElt → RngIntElt
RightStringLength(W, r, s): GrpPermCox, RngIntElt, RngIntElt → RngIntElt
Example: Root Arithmetic
RootHeight(W, r): GrpPermCox, RngIntElt → RngIntElt
CorootHeight(W, r): GrpPermCox, RngIntElt → RngIntElt
RootNorms(W): GrpPermCox → [RngIntElt]
CorootNorms(W): GrpPermCox → [RngIntElt]
RootNorm(W, r): GrpPermCox, RngIntElt → RngIntElt
CorootNorm(W, r): GrpPermCox, RngIntElt → RngIntElt
IsLongRoot(W, r): GrpPermCox, RngIntElt → BoolElt
IsShortRoot(W, r): GrpPermCox, RngIntElt → BoolElt
Example: Root Operations
- Weights
- Reflections
IsReflection(w): GrpFPElt → BoolElt
IsReflection(w): GrpPermElt → BoolElt, ., ., RngInt
Reflections(W): GrpFPCox → [GrpFPCoxElt]
Reflections(W): GrpPermCox → [GrpPermElt]
Example: Reflections
SimpleReflections(W): GrpFPCox → [GrpFPCoxElt]
SimpleReflections(W): GrpPermCox → [GrpPermElt]
SimpleReflectionPermutations(W): GrpPermCox → [GrpPermElt]
Reflection(W, r): GrpPermCox, RngIntElt → GrpPermElt
ReflectionPermutation(W, r): GrpPermCox, RngIntElt → GrpPermElt
SimpleReflectionMatrices(W): GrpPermCox → []
SimpleCoreflectionMatrices(W): GrpPermCox → []
ReflectionMatrices(W): GrpPermCox → []
CoreflectionMatrices(W): GrpPermCox → []
ReflectionMatrix(W, r): GrpPermCox, RngIntElt → []
CoreflectionMatrix(W, r): GrpPermCox, RngIntElt → []
ReflectionWords(W): GrpPermCox → []
ReflectionWord(W, r): GrpPermCox, RngIntElt → []
Example: Action
- Reflection Subgroups
ReflectionSubgroup(W, a): GrpPermCox, SetEnum → GrpPermCox
ReflectionSubgroup(W, s): GrpPermCox, [] → GrpPermCox
StandardParabolicSubgroup(W, J): GrpPermCox, SetEnum → GrpPermCox
IsReflectionSubgroup(W, H): GrpPermCox, GrpPermCox → BoolElt
IsParabolicSubgroup(W, H): GrpPermCox, GrpPermCox → BoolElt
IsStandardParabolicSubgroup(W, H): GrpPermCox, GrpPermCox → BoolElt
Overgroup(H): GrpPermCox → GrpPermCox
Overdatum(H): GrpPermCox → RootDtm
LocalCoxeterGroup(H): GrpPermCox → GrpPermCox, Map
Example: Reflection Subgroups
Transversal(W, H): GrpPermCox, GrpPermCox → SetIndx
TransversalWords(W, H): GrpPermCox, GrpPermCox → SetIndx
TransversalElt(W, H, x): GrpPermCox, GrpPermCox, GrpPermElt → GrpPermElt
Example: Transversals
TransversalElt(W, x, H): GrpPermCox, GrpPermElt, GrpPermCox → GrpPermElt
TransversalElt(W, H, x, J): GrpPermCox, GrpPermCox, GrpPermElt, GrpPermCox → GrpPermElt
Transversal(W, J): GrpFPCox, \{RngIntElt\} → \{@ GrpFPCoxElt @\}
Transversal(W, J, L): GrpFPCox, \{RngIntElt\}, RngIntElt → \{@ GrpFPCoxElt @\}
Transversal(W, J, K): GrpFPCox, \{RngIntElt\}, \{RngIntElt\} → [ GrpFPCoxElt ], [ ]
DirectProduct(W1, W2): GrpPermCox, GrpPermCox → GrpPermCox
Dual(W): GrpPermCox → GrpPermCox
Example: Sum Dual
- Root Actions
- Standard Action
- Braid Groups
- \(W\)-graphs
SetVerbose("WGraph", v): MonStgElt, RngIntElt
Mij2EltRootTable(seq): SeqEnum → SeqEnum[SeqEnum[RngIntElt]]
Name2Mij(name): MonStgElt → SeqEnum
Example: mijseq
Partition2WGtable(pi): SeqEnum → SeqEnum, GrpFPCox
WGtable2WG(table): SeqEnum → GrphUnd
TestWG(W,wg): GrpFPCox, GrphUnd → .
TestWG(W,wg): GrpFPCox, GrphDir → .
TestWG(tp,wg): MonStgElt, GrphDir → .
TestWG(tp,wg): MonStgElt, GrphDir → .
Example: Specht Wgraph
WGelement2WGtable(g,K): GrpFPCoxElt, SetEnum → SeqEnum, SeqEnum
Example: B5Wgraph
GetCells(wg): GrphUnd → SeqEnum
GetCells(wg): GrphDir → SeqEnum
InduceWG(W,wg,seq): GrpFPCox, GrphUnd, SeqEnum → GrphUnd
InduceWG(W,wg,seq): GrpFPCox, GrphDir, SeqEnum → GrphDir
InduceWGtable(J, table, W): SeqEnum, SeqEnum, GrpFPCox → SeqEnum[SeqEnum[RngIntElt]]
IsWGsymmetric(dwg): GrphDir → BoolElt, GrphDir
MakeDirected(uwg): GrphUnd → GrphDir
TestHeckeRep(W,r): GrpFPCox, SeqEnum → .
WG2GroupRep(wg): GrphUnd → SeqEnum
WG2GroupRep(wg): GrphDir → SeqEnum
WG2HeckeRep(W,wg): GrpFPCox, GrphUnd → SeqEnum
WG2HeckeRep(W,wg): GrpFPCox, GrphDir → SeqEnum
WGidealgens2WGtable(dgens,K): SeqEnum, SetEnum → SeqEnum[SeqEnum[RngIntElt]], SetIndx
Example: Wgraph Ideal
WriteWG(file,uwg): MonStgElt, GrphUnd → .
WriteWG(file,dwg): MonStgElt, GrphDir → .
- Related Structures