A normal toric variety is complete if any of the following equivalent conditions hold:
Affine varieties are not complete.
i1 : AA1 = affineSpace 1 o1 = AA1 o1 : NormalToricVariety |
i2 : assert (not isComplete AA1 and isSmooth AA1 and # max AA1 === 1) |
i3 : AA3 = affineSpace 3 o3 = AA3 o3 : NormalToricVariety |
i4 : assert (not isComplete AA3 and isSmooth AA3 and # max AA3 === 1) |
i5 : U = normalToricVariety ({{4,-1,0},{0,1,0}},{{0,1}}); |
i6 : assert (not isComplete U and isDegenerate U and # max U === 1) |
i7 : Q = normalToricVariety ({{1,0,0},{0,1,0},{0,0,1},{1,1,-1}},{{0,1,2,3}}) o7 = Q o7 : NormalToricVariety |
i8 : assert (not isComplete Q and not isSmooth Q and # max Q === 1) |
Projective varieties are complete.
i9 : PP1 = toricProjectiveSpace 1; |
i10 : assert (isComplete PP1 and isProjective PP1 and isSmooth PP1) |
i11 : FF7 = hirzebruchSurface 7; |
i12 : assert (isComplete FF7 and isProjective FF7 and isSmooth FF7 and not isFano FF7) |
i13 : X = smoothFanoToricVariety (4,120); |
i14 : assert (isComplete X and isProjective X and isSmooth X and isFano X) |
i15 : P12234 = weightedProjectiveSpace {1,2,2,3,4}; |
i16 : assert (isComplete P12234 and isProjective P12234 and not isSmooth P12234 and isSimplicial P12234) |
i17 : Y = normalToricVariety ( id_(ZZ^3) | - id_(ZZ^3)); |
i18 : assert (isComplete Y and isProjective Y and not isSmooth Y and not isSimplicial Y) |
There are also complete non-projective normal toric varieties.
i19 : X1 = normalToricVariety ({{1,0,0},{0,1,0},{0,0,1},{0,-1,-1},{-1,0,-1},{-2,-1,0}},{{0,1,2},{0,1,3},{1,3,4},{1,2,4},{2,4,5},{0,2,5},{0,3,5},{3,4,5}}); |
i20 : assert (isComplete X1 and not isProjective X1 and not isSmooth X1 and isWellDefined X1) |
i21 : X2 = normalToricVariety ({{1,0,0},{0,1,0},{0,0,1},{0,-1,2},{0,0,-1},{-1,1,-1},{-1,0,-1},{-1,-1,0}},{{0,1,2},{0,2,3},{0,3,4},{0,4,5},{0,1,5},{1,2,7},{2,3,7},{3,4,7},{4,5,6},{4,6,7},{5,6,7},{1,5,7}}); |
i22 : assert (isComplete X2 and not isProjective X2 and isSmooth X2 and isWellDefined X2) |
i23 : X3 = normalToricVariety ({{-1,2,0},{0,-1,0},{1,-1,0},{-1,0,-1},{0,0,-1},{0,1,0},{0,0,1},{1,0,-2}},{{0,1,3},{1,2,3},{2,3,4},{3,4,5},{0,3,5},{0,5,6},{0,1,6},{1,2,6},{2,4,7},{4,5,7},{2,6,7},{5,6,7}}); |
i24 : assert (isComplete X3 and not isProjective X3 and isSmooth X3 and isWellDefined X3) |
The nonprojective examples are taken from [Osamu Fujino and Sam Payne, Smooth complete toric threefolds with non nontrivial nef line bundles, Proc. Japan Acad. Ser. A Math. Sci. 81 (2005), no. 10, 174-179].