News
3 November 2025: Schläfli lecture by Kathlén Kohn.

Programs for Lie algebras and algebraic groups

tropicalmorphisms.nb

This program illustrates my work with Alejandro Vargas on tropical morphisms from metric graphs to trees. It is primarily intended for visualisation, not optimised for efficiency, and comes with no guarantee of correctness. We used it to make this movie.

UEA

By Willem de Graaf. Variation on UniversalEnvelopingAlgebra in GAP, which takes a basis of the Lie algebra as a parameter.

WeylAlgebra

Weyl Algebras in GAP, another minor variation on de Graaf's UniversalEnvelopingAlgebra.

Blattner

Explicit realization of Lie algebras by vector fields, in GAP; requires UEA and WeylAlg. See this paper for an explanation of the algorithm and its usage.

maximal_subalgebras

Finds all reductive maximal subalgebras of a classical complex Lie algebra, and the corresponding restriction matrices; written in LiE.

SeDiMO v. 3

Computes, using a randomised algorithm, the secant dimensions of minimal orbits. Written in GAP together with Karin Baur and Willem de Graaf. Unzip and untar the archive using
tar xzvf sedimov3.tar.gz
This will create a directory sedimov3; read the files README and sedimo.d for information on the usage.