Maxima Function
poly_grobner_member (poly, polylist, varlist)
Returns true if a polynomial poly belongs to the ideal generated by the
polynomial list polylist, which is assumed to be a Groebner basis. Returns false otherwise.
poly_grobner_member tests whether a polynomial belongs to an ideal generated by a list of polynomials,
which is assumed to be a Groebner basis. Equivalent to normal_form being 0.