The degree of the forms defining the returned map is 10 in the case of cubic fourfolds, and 26 in the case of GM fourfolds.
i1 : K = ZZ/10000019; S = ideal(random(3,Grass(0,5,K)), random(1,Grass(0,5,K)), random(1,Grass(0,5,K))); o2 : Ideal of K[p ..p ] 0 5 |
i3 : X = specialCubicFourfold S; -- computing number of nodes using a probabilistic method... -- got 0 nodes o3 : SpecialCubicFourfold (Cubic fourfold containing a surface of degree 3 and sectional genus 1) |
i4 : time f = unirationalParametrization X; -- used 0.59106 seconds o4 : RationalMap (rational map from PP^4 to PP^5) |
i5 : describe f o5 = rational map defined by forms of degree 10 source variety: PP^4 target variety: PP^5 image: smooth cubic hypersurface in PP^5 dominance: false birationality: false coefficient ring: K |
i6 : image f == ideal X o6 = true |
i7 : degreeMap f o7 = 2 |
The object unirationalParametrization is a method function.