Fabrizio,
In summary: I think you want load(grobner); demo("grobner.demo");
> The example shown by the command demo(grobner)
> does not produce anything:
> grobner_basis ([3*x^2+1, y*x])$
> polysimp (y^2*x + x^3*9 + 2)
I believe you mean describe(grobner) here.
The problem is that there are two distinct packages for Groebner basis
computations.
One is share/affine and the other is share/contrib/Grobner.
describe(grobner) prints some info about share/affine,
and load(grobner) loads stuff from share/contrib/Grobner.
demo("grobner.demo") shows a demo for share/contrib/Grobner.
share/contrib/Grobner/grobner-demo.output shows the demo output.
There is no texinfo documentation for share/contrib/Grobner,
which is a shame, since it seems to work better than share/affine.
Hope this clarifies the situation.
Robert