[GAP Forum] FGA package

[Edmund Robertson]

Dear GAP Forum,

I announce, with great pleasure, that the FGA package, by Christian Sievers 
has been accepted as a refereed GAP package and is available for download 
from the GAP Web site, or from the authors Web page at

http://cayley.math.nat.tu-bs.de/software/sievers/FGA/FGA-1.1.tar.gz

The following description of the functionality of the package is based on 
that of author.

The FGA package provides methods for computing with finitely generated 
subgroups of free groups. It provides a number of new operations for 
free groups such as FreeGeneratorsOfGroup and RankOfFreeGroup, and also 
installs new methods for a number of functions already known to GAP so 
that they can also be used with free groups. These latter functions include 
Normalizer, Centralizer and IsConjugate.

In particular FGA:

- allows you to (constructively) test membership and conjugacy, and to 
compute free generators, the rank, the index, normalizers, centralizers, 
and intersections of groups which are finitely generated subgroups of 
free groups.

- provides generators and a finite presentation for the automorphism 
group of a finitely generated free group and contains a method to
write any such automorphism as word in these generators.


Edmund Robertson

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Professor E F Robertson
Centre for Interdisciplinary Research in Computational Algebra
School of Mathematics and Statistics
Mathematical Institute
University of St Andrews
St Andrews  KY16 9SS
Scotland

Email: edmund at mcs.st-and.ac.uk
Tel:  +44 (0)1334 463743
Fax: +44 (0)1334 463748

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