I know this isn't really a GAP question, but does anyone out there know if
there's a package available that will calculate the invariants of the
action of a (small) finite group on a purely transcendental field
extension over some (arbitrary but infinite) base field? The action can be
given explicitly as the action on the transcendental generators, but ISN'T
a permutation action. (Even though the group is often the symmetric group.)

Hopeful thanks,

Dave Donaghy