[GAP Forum] Update of GAP to version 4.4.5

[Max Neunhoeffer]

Dear Forum,

This is to announce the "Update" to GAP version 4.4.5.

The priority to install this Update is "high", because some of the now
fixed bugs in version 4.4.4 could produce wrong results without warning.

Compared to former "Bugfix" releases, this Update contains not only
bugfixes, but also some new features and extended or fixed documentation.
On the other hand, it is not a full "Release", such that one does not
have to install GAP anew.

The idea behind this new concept is to transfer some new developments or
improvements earlier to the GAP users than it would be possible with full
Releases. This concerns for example package developers who sometimes
have wishes for extensions of the GAP kernel or library.

A small drawback compared to former Bugfixes is the size of the download
archive containing the fixes and extensions. But we hope that for almost
all GAP users this is not a problem nowadays.

For information about fixed bugs and new features see the section about
Release 4.4.5 in

  http://www.gap-system.org/Download/bugs.html

See below for an excerpt.

GAP Bugfixes and Updates are comprehensive, i.e. you can upgrade
from any version of GAP 4.4 to 4.4.5 using this Update.
You should not apply this fix to any version of GAP before GAP 4.4.
(If you run such an old version, please install GAP 4.4.5 directly!)

For download and installation instructions see

  http://www.gap-system.org/Download/upgrade.html

There you also find instructions how to test whether the Update has
been installed successfully. Note that the same page has a section
which describes how to check whether all your installed GAP packages 
are up to date. It might be a good idea to check this after an
upgrade to GAP 4.4.5, as new versions of packages might have been 
released independently of GAP.

For the GAP Group,
  Thomas Breuer, Frank Luebeck, and Max Neunhoeffer

-----------------------------------------------------------------------------

=================================
Excerpt from the list of changes:
=================================

Fixed Bugs
==========

  - An error in the intersection routine for PC groups.

  - Computing the closure of a permutation group by a normalizing element
    could produce a corrupt stabilizer chain.

  - When computing preimages under an embedding into a direct product
    of permutation groups, if the element was not in the image of the
    embedding then a permutation had been returned instead of fail.

  - Two errors in `PowerMod' for polynomials. [Reported by Jack Schmidt]

  - Some methods for computing the sum of ideals returned the first summand
    instead of the sum.

  - InducedPcgs(pcgs,H) sometimes returned a pcgs which is not induced wrt.
    the parent pcgs of pcgs. This led to unpredictable behaviour,
    e. g. when SiftedPcElement was used subsequently.

All of these bugs can cause wrong results.


New or improved mathematical functionality
==========================================

  - The small groups library has been extended by
    - the groups of order p^4, p^5, p^6 for arbitrary primes p,
    - the groups of square-free order, and
    - the groups of cube-free order at most 50000.

  - A new function `StructureDescription' for computing
    structure descriptions for finite groups.

  - The database of precomputed Conway polynomials has been extended
    considerably, and the performance of `ConwayPolynomial' and
    `IsPrimitivePolynomial' for p < 256 has been improved significantly.
    New functions `IsCheapConwayPolynomial' and `RandomPrimitivePolynomial'
    have been added.

  - New functions `ContinuedFractionExpansionOfRoot' and
    `ContinuedFractionApproximationOfRoot' for computing continued fraction
    expansions and continued fraction approximations of real roots of
    polynomials with integer coefficients.

  - A method for `NormalBase' for finite fields has been added.