<!-- #################################################################### -->
<!-- ##                                                                ## -->
<!-- ##  abstract.xml      ResClasses documentation       Stefan Kohl  ## -->
<!-- ##                                                                ## -->
<!-- ##  $Id: abstract.xml,v 1.9 2005/05/17 13:03:50 stefan Exp $      ## -->
<!-- ##                                                                ## -->
<!-- #################################################################### -->

<Abstract>

  This package for &GAP; 4 (at least version 4.4) implements set-theoretic
  unions of residue classes of the ring <M>\mathbb{Z}</M> of the integers,
  of its semilocalisations <M>\Z_{(\pi)}</M> at some finite set of primes
  <M>\pi</M> and of the polynomial rings GF(<M>q</M>)[<M>x</M>] for some
  prime power <M>q</M> as &GAP; domains. <P/>

  It provides basic functionality for computing with these sets, like
  forming intersections, unions and differences. Any of this is also
  supported in the case that one of the operands is a finite set of elements.
  The package also implements the mentioned rings <M>\Z_{(\pi)}</M> as &GAP;
  domains.

</Abstract>

<!-- #################################################################### -->
