Dear Forum,

This is to announce bugfix number 1 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 calculating the gcd of rational functions.
2) A problem with the function `SimpleLieAlgebra' when used with
a field of characteristic 2.
3) Compilation problems on IRIX 6.5, and on some versions of UNIX on alphas.
4) A problem with `CharacterDegrees'.
5) A problem with `Exec' on Solaris2.5 (which caused a segmentation fault).
6) Compilation problems on FreeBSD.
7) A problem with equality testing for conjugacy classes.
8) A problem with computing the gcd of integers, when one of the
arguments is negative, and the other is zero.
9) A problem with `PrintCharacterTable' for tables whose `InfoText'
value contains line breaks.
10) A problem with the enumeration of semigroups.

Error 1) may cause GAP to signal an error.
Error 2) may cause GAP to enter an infinite loop.
Errors 4), 7) and 8) may produce wrong results.

Many thanks to:
J"urgen M"uller for reporting error 1).
Scott Murray for reporting error 2).
Franz Gaehler, Greg Gamble and Joseph Haig for reporting error 3).
Greg Gamble for reporting error 5).
Chris Wensley for reporting error 6).
Ulrike Muthmann for reporting error 7).
J"urgen M"uller for reporting error 8).
Manuel Delgado for reporting error 10).
Burkhard H"ofling for the Macintosh binaries.

Errors 1), 4), 7) and 8) also occur in GAP4.1. 

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

Load the zoo archive `fix4r2n1.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
fix4r2n1.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 changes the kernel. You have to recompile by calling `make' in the
directory in which you unpacked the fix.

Windows users can find a new binary in the file `wbin4r2n1.zoo' in the
`bugfixes' directory: Extract this archive in the same place as the fix
archive to get a new `gapw95.exe' file.

Unfortunately we are not able to provide new Macintosh binaries at the
moment. We hope that, since the kernel change on the Macintosh only affects
Error 8), this will not cause problems for many people. We will try to
provide the new binaries as soon as possible.

You can remove the file `description1' 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, 17-Mar-00

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