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<TitlePage>
  <Title>
    idrel
  </Title>
  <Subtitle>
    Identities among relations
  </Subtitle>
  <Version>
    2.47
  </Version>
  <Author>
    Anne Heyworth<Alt Only="LaTeX"><Br/></Alt>

  </Author>
  <Author>
    Chris Wensley<Alt Only="LaTeX"><Br/></Alt>
<Email>cdwensley.maths@btinternet.com</Email>
<Homepage>https://github.com/cdwensley</Homepage>

  </Author>
  <Date>
    2 June 2024
  </Date>
  <Abstract>
    &IdRel; is a &GAP; package originally implemented in 1999, using the &GAP; 3 language, when the first author was studying for a Ph.D. in Bangor.
<P/>
This package is designed to compute a minimal set of generators for the module of the identities among relators of a group presentation.
It does this using
<List>
<Item>
rewriting and logged rewriting: a self-contained implementation of the Knuth-Bendix process using the monoid presentation associated to the group presentation;
</Item>
<Item>
monoid polynomials: an implementation of the monoid ring;
</Item>
<Item>
module polynomials: an implementation of the right module over this monoid generated by the relators.
</Item>
<Item>
Y-sequences: used as a <E>rewriting</E> way of representing elements of a free crossed module (products of conjugates of group relators and inverse relators).
</Item>
</List>
<P/>
&idrel; became an accepted &GAP; package in May 2015.
<P/>
Bug reports, suggestions and comments are, of course, welcome.
Please contact the last author at <Email>cdwensley.maths@btinternet.com</Email> or submit an issue at the GitHub repository <URL>https://github.com/gap-packages/idrel/issues/</URL>.
  </Abstract>
  <Copyright>
    &copyright; 1999-2024 Anne Heyworth and Chris Wensley<P/>
The &IdRel; package is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
  </Copyright>
  <Acknowledgements>
    This documentation was prepared using the &GAPDoc; <Cite Key='GAPDoc'/> and &AutoDoc; <Cite Key='AutoDoc'/> packages.<P/>
The procedure used to produce new releases uses the package <Package>GitHubPagesForGAP</Package> <Cite Key='GitHubPagesForGAP' /> and the package <Package>ReleaseTools</Package>.<P/>
  </Acknowledgements>
  </TitlePage>