Dear Forum,

Davide Ferrario wrote

I'm working on some small programs in gap, and I have the following 2 questions:
(I'm running a gap4r1 bugfix 1 version, compiled on a linux box
i686-pc-linux-gnu-gcc, with pargapmpi installed)

1. Consider the following strange behavior:

---BEGIN

gap> G:=DihedralGroup(6);
<pc group of size 6 with 2 generators>
gap> tm:=TableOfMarks(G);
TableOfMarks( Group( [ f1, f2 ] ) )
gap> H:=RepresentativeTom(tm,2);
Group([ f2 ])
gap> th:=CharacterTable(H);
CharacterTable( Group([ f2 ]) )
gap> Size(H);
2
gap> SizesConjugacyClasses(th);
[ 1, 2/3, 2/3 ]

[...]

---END

What am I doing wrong? What does it mean? How can I avoid this problem?

The above behaviour is due to a bug in the code for tables of marks.
It may happen that the two arguments of `RepresentativeTom' refer to
different orderings of subgroups, which leads to inconsistencies;
For example, the group `H' that claims to have order 2 has in fact order 3.

This will be corrected with the next bugfix.
Thanks for reporting this bug.

Thomas Breuer