> < ^ Date: Wed, 02 Jul 1997 10:45:52 +0100 (BST)
> < ^ From: Alexander Hulpke <hulpke@math.colostate.edu >
^ Subject: Fix #5

This is to announce a bugfix for the GAP library. The priority
of this fix is medium.

This fix corrects:
1) An error in the homomorphism test for mappings from finitely presented
groups.

2) An error in the homomorphism test for mappings to finitely presented
groups (it is not possible to simply evaluate relators).

3) An error in 'PermChars'.

Errors 1 and 2 may give wrong results, error 3 may cause GAP to issue an error
message.

Many thanks to Cosimo Fornaro for finding and fixing error 1, to Gunter Malle
for reporting error 3 and to Goetz Pfeiffer for fixing it.

To apply the fix, load the zoo archive 'fix5.zoo' from the
bugfixes web page
http://www-groups.dcs.st-and.ac.uk/~gap/Info/bugfixes.html
Alternatively you can find this file in the 'bugfixes' directory of the
GAP ftp distribution.

Unpack the file in the home directory of your GAP distribution (the
directory containing the 'lib' and 'etc' directories) using 'unzoo -x
fix5.zoo' (On a PC or a Mac you will have to enter the argument line after
the call to 'unzoo'.) This will replace the erraneous files by fixed versions.
Make sure you have write permissions when applying the fix.

You can remove the file 'description5' afterwards.

You won't need to recompile anything.

Best regards,

Alexander Hulpke

#############################################################################
# these commands should run without error if fix5 has been applied.
# note that the second part of the test requires the CHEVIE share package!
#
F := FreeGroup (2);
rels := [ F.1^2, F.2^3, (F.1*F.2)^5 ];
G := F / rels;
phi := GroupHomomorphismByImages (G, Group((1,2)), [G.1, G.2], [(1,2),(1,2)]);
if IsGroupHomomorphism(phi) then
  Error("is not homomorphism");
fi;
phi := GroupHomomorphismByImages (G, Group((1,2,3),(1,2,3,4,5)),
  [G.1, G.2], [(1,4)(3,5),(1,2,3)]);
if not IsGroupHomomorphism(phi) then
  Error("is homomorphism");
fi;
phi := GroupHomomorphismByImages (G, G,G.generators,G.generators);
if not IsGroupHomomorphism(phi) then
  Error("is homomorphism");
fi;
phi := GroupHomomorphismByImages (G, G,G.generators,Reversed(G.generators));
if IsGroupHomomorphism(phi) then
  Error("is not homomorphism");
fi;

#
# THIS PART OF THE TEST REQUIRES CHEVIE TO BE INSTALLED!
RequirePackage("chevie");
H4:=CoxeterGroup("H",4);
tt:=CharTable(H4);
PermChars(tt,75);


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