i1 : X = specialGushelMukaiFourfold "tauquadric";
o1 : ProjectiveVariety, GM fourfold containing a surface of degree 2 and sectional genus 0

i2 : describe X
o2 = Special GushelMukai fourfold of discriminant 10(')
containing a surface in PP^8 of degree 2 and sectional genus 0
cut out by 6 hypersurfaces of degrees (1,1,1,1,1,2)
and with class in G(1,4) given by s_(3,1)+s_(2,2)
Type: ordinary
(case 1 of Table 1 in arXiv:2002.07026)

i3 : time U' = associatedK3surface X;
 used 17.1826 seconds
o3 : ProjectiveVariety, K3 surface associated to X

i4 : (mu,U,C,f) = building U';

i5 : ? mu
o5 = multirational map consisting of one single rational map
source variety: 5dimensional subvariety of PP^8 cut out by 5 hypersurfaces of degree 2
target variety: PP^4
dominance: true

i6 : ? U
o6 = surface in PP^4 cut out by 5 hypersurfaces of degrees 3^1 4^4

i7 : first C  two disjoint lines
o7 = curve in PP^4 cut out by 5 hypersurfaces of degrees 1^1 2^4
o7 : ProjectiveVariety, curve in PP^4 (subvariety of codimension 1 in U)

i8 : assert(image f == U')
