
The GAP 4 package `Polycyclic'
==============================

Introduction
------------

This is the package `Polycyclic' written for GAP 4.  It provides a
basis for working with polycyclic groups defined by polycyclic
presentations.

To have the  full functionality of the package  available you need the
GAP 4 package Alnuth and the Computer Algebra System Kant installed.

The features of this package include
        
        - creating a polycyclic group from a polycyclic presentation 

        - arithmetic in a polycyclic group

        - computation with subgroups and factor groups of a polycyclic
          group

        - computation of standard subgroup series such as the derived 
          series, the lower central series

        - computation of the first and second cohomology 

        - computation of group extensions

        - computation of normalizers and centralizers

        - solutions to the conjugacy problems for elements and subgroups

        - computation of Torsion and various finite subgroups

        - computation of various subgroups of finite index

        - computation of teh Schur multiplicator, the non-abelian
          exterior square and the non-abelian tenor square

There is a manual in the subdirectory 'doc' written in plain TeX which
describes the available functions in detail.

If you have used `Polycyclic', please let  us know by sending an email
to one (or both) of us.  If you  have found important features missing
or if there is a bug, we would appreciate it very much  if you send us
an email.

Bettina Eick  <beick@tu-bs.de>
Werner Nickel <nickel@mathematik.tu-darmstadt.de>

You  can also reach  us by sending an email   to the general GAP email
address for problems with GAP:

                     gap-trouble@dcs.st-and.ac.uk

Contents
--------

With this version you should have obtained the following files and
directories:

        README          this file

        init.g          the file that initializes this package
        read.g          the file that reads in the package        

        PackageInfo.g   the file for the new package loading mechanism

        doc             the manual

        htm             the manual as web pages, start with the page
                        htm/chapters.htm 

        gap             the GAP code, it contains

                action   actions of polycyclic groups and orbit-stabilizer
                basic    basic stuff for pcp groups
                cohom    cohomology for pcp groups
                exam     examples of pcp groups
                matrep   matrix representations for pcp groups
                matrix   basic stuff for matrices and lattices
                pcpgrp   higher level functions for pcp groups

        etc              developers' stuff



Installation
------------

Make sure  that the GAP 4 package  Alnuth is installed to  have the full
range of methods available in polycyclic.

There are two ways of installing the package.  If you have permission
to add files to the installation directory of GAP 4 on your system,
you may install polycyclic in the pkg subdirectory of the GAP
installation tree.  If you do not, you can also install polycyclic in
a directory where you have write permissions.  For general advice, see
also the GAP 4 manual about the installation of GAP packages.

--  Installation in the GAP 4 pkg subdirectory on a Unix system.

    We assume that the archive file polycyclic.tar.gz or
    polycyclic.tar is present in pkg and that the current directory is
    pkg.  All that needs to be done is to unpack the archive.

    sh > gunzip polycyclic.tar.gz        # for the gzipped tar-archive
                                         # skip if you have the .tar version
    sh > tar xf polycyclic.tar 

    The tar-command has unpacked the code into a directory called
    'polycyclic' in the current directory. You can check if GAP
    recognizes the polycyclic package by starting GAP and doing the
    following:

    sh > gap4
    [... startup messages ...]
    gap> RequirePackage("polycyclic");
    true
    gap>     


--  Installation in a private directory

    Let's say you would like to install polycyclic in a directory
    called mygap.  Create a subdirectory 'pkg' in mygap and move the
    polycyclic archive into that subdirectory.

    sh > cd mygap
    sh > mkdir pkg
    sh > mv polycyclic.tar.gz pkg
    sh > gunzip polycyclic.tar.gz        # for the gzipped tar-archive
                                         # skip if you have the .tar version

    sh > tar xf polycyclic.tar 

    The tar-command has unpacked the code into a directory called
    'polycyclic' in the current directory. You can check if GAP
    recognizes the polycyclic package by starting GAP and doing the
    following.  GAP needs to be told that it should scan the directory
    mygap/pkg for GAP packages.  This is achieved by calling gap with
    the option -l.  Note the semicolon and the single quotes.

    sh > gap4 -l ';mygap/'
    [... startup messages ...]
    gap> RequirePackage("polycyclic");
    true
    gap>     

