Dear Forum,

This is to announce bugfix number 4 for GAP 4.1. The priority of this fix
is high.

One of the errors fixed by this fix turns also up in the versions
of GAP3, see below. However we do not have a fix for GAP3.

We note that bugfix number 3 was only applicable to the Macintosh versions
of GAP4.

You should not apply this fix to any version of GAP3.

This fix corrects problems with:

1) `EpimorphismNilpotentQuotient',
2) `CyclicGroup',
3) computing powers of some finite field elements,
4) `SaveWorkspace',
5) `NumberFFVector',
6) `PrimePowerComponents' for pc groups,
7) `time' on the Macintosh.

Error 3, 5, and 6 might produce wrong results.

Many thanks to:
Michael Reed for reprting error 1),
Stefan Kohl for reporting error 2),
David Bowen for reporting 3),
Craig Struble for reporting error 4),
Max NeunHoeffer for reporting error 5),
Bettina Eick for reporting error 6),
Charles Wright for reporting error 7).

Burkhard H"ofling for fixing error 7 and for the Macintosh binaries.

Error 3) also turns up in GAP3. Computing `( Z( q )^m )^n' may give
wrong results. In GAP3.4.4 for example:

gap> ( Z(3^10)^36369 )^59048;
Z(3^10)^13568

and this last answer should be identity of the field with 3^10
elements.

Load the zoo archive 'fix4r1n4.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
fix4r1n4.zoo'. `unzoo' may ask you for permissions to overwrite files,
answer this with Y)es or A)ll. This will replace the erroneous file 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 wbin4r1n4.zoo in the
`bugfixes' directory: Extract this archive in the same place as the fix
archive to get a new gapw95.exe file.

Macintosh users should download the file `bin4r1n4-PPC.sit' (for PPC
machines) or `bin4r1n4-68k.sit' (for 68k machines), from the `bugfixes'
directory.

If you get one of these precompiled binaries you do not need to get any
precompiled binaries that would have come with earlier fixes (these old
binaries are obsolete now). Similarly, if you cannot find these binaries but
have further, newer, fixes to install check whether new binaries with these
fixes did not make the binaries of this fix obsolete.

You can remove the file 'description4' afterwards.

Willem de Graaf, 1-Oct-99

#############################################################################
##
## These commands should run without trouble or error if the fix has been 
## applied.
##

v := [1,0]*Z(4)^0;
MakeImmutable(v);
ConvertToVectorRep(v,4);
if not NumberFFVector(v,4)=4 then Print("Error_1\n"); fi;

code := 42000196945440135986257788391020509453777404676419;
H := PcGroupCode( code, 1008 );
list := Pcgs(H);;
g := Comm( list[2], list[1] );;
p:=PrimePowerComponents( g );
li:= List( p, Order );
if li <> [ 4, 9, 7 ] then Print( "Error2\n"); fi;

F:= GF(3^10);
r:= PrimitiveRoot( F );
qq:= Size( F ) - 1;
if (r^36369)^qq <> One(F) then Print("Error3\n"); fi;

f := FreeGroup(1);
g := f / [f.1^4];
EpimorphismNilpotentQuotient(g);

CyclicGroup( NextPrimeInt(1000000000) );