-- -*- M2-comint -*- hash: 13114819483214090177

i1 : K = ZZ/10000019;

i2 : -- map defined by the cubics through the secant variety to the rational normal curve of degree 6
     Phi = multirationalMap rationalMap(ring PP_K^6,ring GG_K(2,4),gens ideal PP_K([6],2));

o2 : MultirationalMap (rational map from PP^6 to GG(2,4))

i3 : time Psi = inverse2 Phi;
 -- used 0.334196s (cpu); 0.296342s (thread); 0s (gc)

o3 : MultirationalMap (birational map from GG(2,4) to PP^6)

i4 : assert(Phi * Psi == 1)

i5 : Phi' = Phi || Phi;

o5 : MultirationalMap (rational map from PP^6 x PP^6 to GG(2,4) x GG(2,4))

i6 : time Psi' = inverse2 Phi';
 -- used 1.40617s (cpu); 1.09116s (thread); 0s (gc)

o6 : MultirationalMap (birational map from GG(2,4) x GG(2,4) to PP^6 x PP^6)

i7 : assert(Phi' * Psi' == 1)

i8 : 
