Hi,

I guess I can do this. There is the GAP3 file PrimitiveInvariant.g which
contains programs to compute primitive invariants, polynomials that
characterize subgroups of the symmetric group and that are of use in
Galois theory. The main algorithms encoded by the programs generalize
methods of K. Girstmair for calculating minimal primitive invariants.

PrimitiveInvariant.g is available in the "deposit" ftp subdirectory, as
pub/gap/gap-3.4.4/deposit/gap/priminv.g
or by following the links "Get GAP...more" and "GAP3 User contributions"
from the GAP main Web page, to arrive at the URL
www-history.mcs.st-and.ac.uk/~gap/Info/deposit.html.
The article "Calculs d'Invariants Primitifs de Groupes finis" which gives
the theory behind the algorithms will appear in RAIRO -Informatique
Theorique et Programmation and is also available at
www-calfor.lip6.fr/~abdeljao.

I hope that you will find these programs useful. I would be glad to
correspond further with anybody who has questions about them or has
applications for them.

Ines Abdeljaoued

< Ines.Abdeljaoued@insat.rnu.tn >