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Dear Gap-Forum,

This is to announce bugfix number 5 for GAP 4b4. The priority of this fix

is high.

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

To apply the fix, you must have installed bugfixes 1 to 4 first.

This fix corrects:

1) An error in computing coefficients of a multivariate polynomail that

happens to be univariate.

2) A Problem with `GQuotient' when applied to free groups.

3) A too generous method installation for `MinimalGeneratingSet'. It also

adds redispatch methods for solvable permutation groups as a convenience.

4) A problem with forming factor groups of direct products

5) An error when creating finite fields by special polynomials

6) An error in `CharacterTableDirectProduct'

7) Recursion problems when computing with algebras.

8) A misleading error message in `ApplicableMethod'

Error 1 may lead to wrong results in the polynomial arithmetic.

Errors 2-8 lead to error messages.

Many thanks to:

David Hough for reporting error 1.

Esteban Crespi for reporting error 2 and problem 3.

Russell Blyth for reporting error 4.

Jacob Hirbawi for reporting error 5 and 6.

Craig Struble for reporting error 7.

Burkhard H"ofling for reporting problem 8.

Load the zoo archive 'fix4b4n5.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 fix4b4n5.zoo'

(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'.) This will replace the

erraneous file by fixed versions.

Make sure you have write permissions when applying the fix.

This fix does not change the kernel. You do not need to recompile. (Windows

users however should get the latest compiled binary in the file

`winbin2a.zoo' from the bugfixes page.)

You can remove the file 'description4' afterwards.

Alexander Hulpke, 6-Nov-98

############################################################################# ## ## These commands should run without error if the fix has been applied. ## m:=[[3,3,3,3,3],[3,2,3,2,3],[3,3,2,2,3],[3,2,2,1,2],[3,3,3,2,2]]; r := Indeterminate(Rationals,"r"); mm := List(m,x->List(x,y->r^y)); d:=Determinant(mm); if Length(Factors(d))<>15 then Error("arithmetic bug!"); fi; G := Group((1,2,3),(1,2)); F := FreeGroup("a","b"); GQuotients(F,G); G:=Group((1,4)(2,6)(3,5),(1,4)(2,5)(3,6),(1,3,2)(4,5,6),(1,2,3)(4,5,6)); MinimalGeneratingSet(G);

G:=DirectProduct(AlternatingGroup(4),DihedralGroup(4));

C:=Centre(G);

F:=FactorGroup(G,C);

GF(2,UnivariatePolynomial(GF(2),Z(2)*[1,1,1,0,0,0,0,1,1],1));

c2:=CharacterTable("Cyclic",2);

c4:=CharacterTableDirectProduct(c2,c2);

A := FreeAlgebra(GF(7), 2); x := GeneratorsOfAlgebra(A)[1]; y := GeneratorsOfAlgebra(A)[2]; I := Ideal(A, [x*y - y*x, x*x, y*y]); B := A/I;

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