# Systems related to Group Theory

# Sisyphos

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# SISYPHOS - Computing in modular group algebras of p-groups #
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# Martin Wursthorn #
# Mathematisches Institut B, 3.Lehrstuhl #
# Universitaet Stuttgart #
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## Introduction

SISYPHOS is a program package developed to compute with p-groups and
their modular group algebras. It originated in an implementation of an
algorithm by Roggenkamp, Scott and the author to test such group
algebras for isomorphisms. This algorithm has been modified and
improved to be applicable to p-groups as well. The following features
are incorporated in the current implementation:
- features dealing with modular group algebras of p-groups:
- Symbolic computations with elements,
- computation of centre, centralizers, lie ideals,
- computing with subspaces and ideals,
- isomorphism tests for such group algebras,
- computation of a polycyclic presentation of the normalized units group,
- features dealing with p-groups:
- (outer) automorphisms of polycyclically presented p-groups,
- isomorphisms between two polycyclically presented groups or a
- freely presented and a polycyclically presented group,
- tests for isomorphisms between two polycyclically presented groups
- or a freely presented and a polycyclically presented group,
- several output formats are supported (generators, element lists,
polycyclic presentations for normalized automorphism groups)

The package can be used either as a GAP shared library via a special
interface that allows the program to be called from within GAP by
special GAP functions (see GAP documentation) or as a standalone
program with its own user interface. The first possibility only allows
access to the routines dealing with p-groups, but has the advantage that
the results can be processed by GAP without any conversions. The second
possibility gives access to all features of SISYPHOS, but though it is
still possible to have some of the routines produce output in a GAP
compatible format, you will have to reformat the output in general to
resue it in some other computer algebra package.
Like GAP, the standalone version of SISYPHOS is an interactive system
controlled by a command language. this command language, called 'Lapidar'
is rather simple and does not yet support any structures that alter the
flow of control, like branching instructions and loops. This language
is described in the SISYPHOS manual.

The following instructions refer to the standalone version only. If you
want to install SISYPHOS as GAP shared library, follow the instructions
in the GAP manual.

## Implementation

SISYPHOS is written in ANSI-C and should run on every UNIX system (and
some non-UNIX systems) that provides an ANSI-C compiler (e.g. GNU cc).
Compilers keeping to the old C standard will not be able to compile the
sources.

## Getting the sources

The sources for SISYPHOS, several group libraries and additional
programs are available via anonymous ftp from
http://web.mathematik.uni-stuttgart.de/sisyphos/

## Contact address

In any case of difficulties whether with the installation or the usage of
SISYPHOS, especially if you encounter any bugs send an email to the
following address `pluto@machnix.mathematik.uni-stuttgart.de`

.
It is very helpful if you include a copy of the input that produced the
bug and the (erroneous) output of SISYPHOS. Moreover any form of
constructive criticism is welcome. The program in its current state is
by no means finished but is developped further permanently.

Martin Wursthorn

Mathematisches Institut B

3. Lehrstuhl

Universitaet Stuttgart

70550 Stuttgart

Tel.: +49 (0)711 685 5517

Fax.: +49 (0)711 685 5322

Sisyphos has been encorporated into
GAP.

Special Purpose Systems

webmaster@can.nl

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Last updated: May 7, 1998