# Semigroups

Version 2.8.0

This project is maintained by J. D. Mitchell

## Getting Semigroups

To get the latest version of the package download the archive file semigroups-x.x.x.tar.gz from the Semigroups webpage, and inside the pkg subdirectory of your GAP installation unpack semigroups-x.x.x.tar.gz, by, for example, doing:

gunzip semigroups-x.x.x.tar.gz; tar xvf semigroups-x.x.x.tar


This will create a subdirectory semigroups-x.x.x.

## Issues

For questions, remarks, suggestions, and issues please use the issue tracker.

## Installation

It is assumed that you have a working copy of GAP with version number 4.8.0 or higher. The most up-to-date version of GAP and instructions on how to install it can be obtained from the main GAP page.

The following is a summary of the steps that should lead to a successful installation of Semigroups:

• get the IO package version 4.4.4 or higher

• get the Orb package version 4.7.3 or higher. Both Orb and Semigroups perform better if Orb is compiled, so compile Orb!

• this step is optional: certain functions in Semigroups require the Grape package to be available and fully compiled; a full list of these functions can be found in the first chapter of the manual. To use these functions make sure that the Grape package version 4.5 or higher is available.

If Grape is not fully installed, then Semigroups can be used as normal with the exception that the functions listed in the first chapter of the manual will not work.

• this step is optional: the non-deterministic version of the function Normalizer requires the genss package to be loaded. If you want to use this function, then please ensure that the genss package version 1.5 or higher is available.

• download the package archive semigroups-x.x.x.tar.gz from the Semigroups webpage.

• unzip and untar the file semigroups-x.x.x.tar.gz, for example, using

 gunzip semigroups-x.x.x.tar.gz; tar xvf semigroups-x.x.x.tar 

this should create a directory called semigroups-x.x.x.

• locate the pkg directory of your GAP directory, which contains the directories lib, doc and so on. Move the directory semigroups-x.x.x into the pkg directory (if it is not there already).

• start GAP in the usual way.

• type LoadPackage("semigroups");

Enjoy!