Related Structures

In this section functions for creating other structures from a root datum are briefly listed. See the appropriate chapters of the Handbook for more details.

RootSystem(R) : RootDtm -> RootSys
The root system corresponding to the root datum R. See Chapter ROOT SYSTEMS.
CoxeterGroup(GrpFPCox, R) : Cat, RootDtm -> GrpFPCox
The (split) Coxeter groupwith root datum R. See Chapter COXETER GROUPS. The braid group and pure braid group can be computed from the Coxeter group using the commands described in Section Braid Groups.
CoxeterGroup(R) : RootDtm -> GrpPermCox
CoxeterGroup(GrpPermCox, R) : Cat, RootDtm -> GrpPermCox
The permutation Coxeter group with root datum R. See Chapter COXETER GROUPS.
ReflectionGroup(R) : RootDtm -> GrpMat
CoxeterGroup(GrpMat, R) : Cat, RootDtm -> GrpPermCox
The reflection group of the root datum R. See Chapter REFLECTION GROUPS.
LieAlgebraHomorphism(phi,k) : Map, Rng -> AlgLie
The homomorphism of reductive Lie algebras over the ring k corresponding to the root datum morphism φ. See Chapter LIE ALGEBRAS.
LieAlgebra(R, k) : RootDtm, Rng -> AlgLie
The reductive Lie algebraover the ring k with root datum R. See Chapter LIE ALGEBRAS.
GroupOfLieType(R, k) : RootDtm, Rng -> GrpLie
The group of Lie typeover the ring k with root datum R. See Chapter GROUPS OF LIE TYPE.
GroupOfLieTypeHomomorphism(phi, k) : Map, Rng -> GrpLie
The algebraic homomorphism of groups of Lie type over the ring k corresponding to the root datum morphism φ. See Chapter GROUPS OF LIE TYPE.

Example RootDtm_Related (H104E33)

> R := RootDatum("b3");
> SemisimpleType(LieAlgebra(R, Rationals()));
B3
> #CoxeterGroup(R);
48
> GroupOfLieType(R, Rationals());
$: Group of Lie type B3 over Rational Field
V2.28, 13 July 2023