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Dear GAP-Forum,

Akihiro Munemasa noticed a bug (politely denoted by him only as 'strange

behaviour') in the 'CharTable' routine.

It will arise, if there is no 'freedom' for the degrees of the non

linear characters, i.e. if the character degrees are determined exactly

by the number of classes and the number of linear characters.

In this case, due to a forgotten '=', the largest character

degrees are accidently thrown away, leading to problems.

Fixing this bug fortunately is very easy (though I hope, this fix will also

be included in the next patch): In the library file grpctbl.g change

line 272 (which also is identified uniquely by its contents) from

D.degreePool:=Filtered(D.degreePool,i->i[1]>1 and i[1]<z/2);

to

D.degreePool:=Filtered(D.degreePool,i->i[1]>1 and i[1]<=z/2);

GAP successfully computed the character table of all solvable

nonabelian groups of order at most 100, except those of order 27.

With this fix, GAP will compute the character tables of all these

groups (and also the non solvable ones).

Side remark: 27 is a prime power. For groups of prime power order,

CharTablePGroup normally works somehow faster than CharTable. As we were

planning to use CharTablePGroup in these cases instead of the standard

Dixon/Schneider algorithm, I never checked the two nonabelian groups of

size 27. I better had. Please excuse this stupid bug.

Yours

Alexander Hulpke

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