gap-aclib - 1.3.2-4 main

GAP is a system for computational discrete algebra, with particular emphasis
on Computational Group Theory. GAP provides a programming language, a library
of thousands of functions implementing algebraic algorithms written in the GAP
language as well as large data libraries of algebraic objects. GAP is used in
research and teaching for studying groups and their representations, rings,
vector spaces, algebras, combinatorial structures, and more.
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The AClib package contains a library of almost crystallographic groups and a
some algorithms to compute with these groups. A group is called almost
crystallographic if it is finitely generated nilpotent-by-finite and has no
non-trivial finite normal subgroups. Further, an almost crystallographic
group is called almost Bieberbach if it is torsion-free. The almost
crystallographic groups of Hirsch length 3 and a part of the almost
cyrstallographic groups of Hirsch length 4 have been classified by Dekimpe.
This classification includes all almost Bieberbach groups of Hirsch lengths 3
or 4. The AClib package gives access to this classification; that is, the
package contains this library of groups in a computationally useful form. The
groups in this library are available in two different representations. First,
each of the groups of Hirsch length 3 or 4 has a rational matrix
representation of dimension 4 or 5, respectively, and such representations
are available in this package. Secondly, all the groups in this libraray are
(infinite) polycyclic groups and the package also incorporates polycyclic
presentations for them. The polycyclic presentations can be used to compute
with the given groups using the methods of the Polycyclic package.
The package was written by Karel Dekimpe and Bettina Eick.