Dear Forum,

This is to announce bugfix number 4 for GAP 4.2. The priority of this fix
is high.

You should not apply this fix to any version of GAP3, nor to any
version of GAP4.1.

This fix corrects:
1) a problem with the `\in' method for equivalence relations,
2) a problem with `IsReesCongruence',
3) a problem with `NormalIntersection',
4) a problem with calculating irreducible characters,
5) a problem with calculating preimages of group homomorphisms,
6) a problem with the help system.

Errors 1), 2), 5) may cause GAP to produce wrong results.
We note that they also occur in GAP4.1.

Errors 3), 4), 6) may cause GAP to signal an error.

Many thanks to:
Robert Morse for reporting and fixing error 1),
Isabel Araujo for reporting and fixing error 2),
Andy Tonks for reporting error 3),
Leonard Soicher for reporting errors 5) and 6).

Installing the bugfix.
======================

Load the zoo archive `fix4r2n4.zoo' from the bugfixes web page
http://www-gap.dcs.st-and.ac.uk/~gap/Info4/bugfixes.html
Alternatively you can find this file in the `bugfixes' directory of the
GAP4 ftp distribution.

Unpack the file in the home directory of your GAP distribution (the
directory containing the `lib' and `grp' directories) using `unzoo -x
fix4r2n4.zoo'. `unzoo' may ask you for permissions to overwrite files,
answer this with Y)es or A)ll. This will replace the erroneous files by
fixed versions.

(On a PC or a Mac you will have to copy `unzoo' in the same directory and
enter the argument line after the call to `unzoo'.)
Make sure you have write permissions when applying the fix.

This fix does not change the kernel. Therefore you do *not* have to recompile.

You can remove the file `description4' afterwards.

After installing the bugfix you can test whether
the bugfix has been applied correctly by starting GAP from the `gap4r2'
directory and issuing

gap> ReadTest("tst/bugfix.tst");
+ bugfixes test
+ GAP4stones: 835
true

(The output should be like this if the bugfixes have been installed
correctly. The number of GAP4stones may vary according to your system.)

Willem de Graaf, 20-July-00