Operations on Elements

Contents

Basic Operations

g * h : GrpLieElt, GrpLieElt -> GrpLieElt
The product of two elements of a group of Lie type. If the Normalising flag is set for the group, then the product is normalised using the algorithms of [CMT04], [CHM08]. Otherwise, the words are just concatenated.

Example GrpLie_GrpLieEltProduct (H110E10)

If the Normalising flag is set, the product is normalised, otherwise multiplication is just concatenation.
> G := GroupOfLieType("G2", GF(3) : Normalising:=false );
> V := VectorSpace(GF(3),2);
> g := elt< G | 1,2,1,2, V![2,2], <1,2>,<5,1> >;
> h := elt< G | <3,2>, V![1,2], 1 >;
> g*h;
n1 n2 n1 n2 (2 2) x1(2) x5(1) x3(2) (1 2) n1
> H := GroupOfLieType("G2", GF(3) : Normalising:=true  );
> g := elt< H | 1,2,1,2, V![2,2], <1,2>,<5,1> >;
> h := elt< H | <3,2>, V![1,2], 1 >;
> g*h;
x2(1) x3(1) (1 2) n1 n2 n1 n2 n1 x4(1)
g ^ -1 : GrpLieElt -> GrpLieElt
Inverse(G) : GrpLieElt -> GrpLieElt
The inverse of the element g of a group of Lie type.
g ^ n : GrpLieElt, RngIntElt -> GrpLieElt
The nth power of the element g of a group of Lie type.
g ^ h : GrpLieElt, GrpLieElt -> GrpLieElt
The conjugate h - 1gh, where g and h are elements of a group of Lie type.
(g, h) : GrpLieElt, GrpLieElt -> GrpLieElt
Commutator(g, h) : GrpLieElt, GrpLieElt -> GrpLieElt
The commutator g - 1h - 1gh of g and h, where g and h are elements of a group of Lie type.
Normalise(simg) : GrpLieElt ->
Normalize(simg) : GrpLieElt ->
Normalise(g) : GrpLieElt -> GrpLieElt
Normalize(g) : GrpLieElt -> GrpLieElt
Normalise the element g of a group of Lie type G. The procedural form is slightly more efficient than the functional form. If the Normalise flag is set for G, this operation has no effect. This uses the algorithms of [CMT04], [CHM08].

Example GrpLie_GrpLieEltArith (H110E11)

Arithmetic in groups of Lie type.
> k<z> := GF(4);
> G := GroupOfLieType("C3", k);
> V := VectorSpace(k, 3);
> g := elt< G | 1,2,3, <3,z>,<4,z^2>, V![1,z^2,1] >;
> g;
n1 n2 n3 x3(z) x4(z^2) ( 1 z^2   1)
> h := elt< G | [0,1,z,1,0,z^2,1,1,z] >;
> h;
x2(1) x3(z) x4(1) x6(z^2) x7(1) x8(1) x9(z)
> g * h^-1;
x3(1) x5(z) x6(z^2) x8(1) (z^2 z^2   z) n1 n2 n3 x3(z^2) x5(z^2)
> g^3;
x3(z) x5(1) x7(z^2) x8(z^2) ( 1   1   z) n1 n2 n3 n1 n2 n3 n1 n2 n3 x1(1)
x2(z^2) x3(1) x4(z) x7(z) x9(z)

Decompositions

Bruhat(g) : GrpLieElt -> GrpLieElt, GrpLieElt, GrpLieElt, GrpLieElt
Given an element g of a group of Lie type the Bruhat decomposition of g is returned. The function returns elements u, h, /dot w, u' with the properties described in Subsection Twisted Groups of Lie type and so that g=uh/dot wu'.

Example GrpLie_Bruhat (H110E12)

> k<z> := GF(4);
> G := GroupOfLieType("C3", k);
> V := VectorSpace(k, 3);
> g := elt< G | 1,2,3, <3,z>,<4,z^2>, V![1,z^2,1] >;
> Normalise(g);
x7(z^2) x8(z^2) (z^2 z^2   z) n1 n2 n3 x3(1) x6(z)
> u, h, w, up := Bruhat(g);
> u; h; w; up;
x7(z^2) x8(z^2)
(z^2 z^2   z)
n1 n2 n3
x3(1) x6(z)
MultiplicativeJordanDecomposition(x) : GrpLieElt -> GrpLieElt, GrpLieElt
The multiplicative Jordan decomposition of the element x of the group of Lie type.

Conjugacy and Cohomology

ConjugateIntoTorus(g) : GrpLieElt -> GrpLieElt, GrpLieElt
Given a semisimple element g in a finite group of Lie type, return a torus element t and conjugator x such that t=xgx - 1. The elements returned may be defined over a larger field than the input element.
ConjugateIntoBorel(g) : GrpLieElt -> GrpLieElt, GrpLieElt
Given a semisimple element g in a finite group of Lie type, return a Borel element b and conjugator x such that b=xgx - 1. The elements returned may be defined over a larger field that the input element. Although any element of a group of Lie type can be conjugated into the Borel subgroup, this function is currently only implemented for semisimple elements.
Lang(c, q) : GrpLieElt, RngIntElt -> GrpLieElt
Given an element c in a finite group of Lie type and q a power of the characteristic, return a solution a of the Lang equation c = a - F a. Here F is the Frobenius automorphism gotten by taking qth powers in the field.
V2.28, 13 July 2023