i1 : X = specialFourfold(PP_(ZZ/65521)[2,2]);
o1 : ProjectiveVariety, cubic fourfold containing a surface of degree 4 and sectional genus 0
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i2 : W = mirrorFourfold X;
o2 : ProjectiveVariety, fourfold in PP^5 containing a surface of degree 10 and sectional genus 7
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i3 : U = surface W;
o3 : ProjectiveVariety, surface in PP^5 (subvariety of codimension 2 in hypersurface in PP^5 defined by a form of degree 2)
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i4 : mirrorFourfold W
o4 = X
o4 : ProjectiveVariety, cubic fourfold containing a surface of degree 4 and sectional genus 0
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i5 : (building associatedK3surface X)_1
o5 = U
o5 : ProjectiveVariety, surface in PP^5 (subvariety of codimension 2 in hypersurface in PP^5 defined by a form of degree 2)
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i6 : assert(oo === U)
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i7 : X' = specialFourfold "tau-quadric";
o7 : ProjectiveVariety, GM fourfold containing a surface of degree 2 and sectional genus 0
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i8 : W' = mirrorFourfold X';
o8 : ProjectiveVariety, a PP^4 containing a surface of degree 8 and sectional genus 6
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i9 : U' = surface W';
o9 : ProjectiveVariety, surface in PP^4
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i10 : mirrorFourfold W'
o10 = X'
o10 : ProjectiveVariety, GM fourfold containing a surface of degree 2 and sectional genus 0
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i11 : (building associatedK3surface X')_1
o11 = U'
o11 : ProjectiveVariety, surface in PP^4
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i12 : assert(oo === U')
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