The numerical-dimension conjecture for pseudo-effective divisors orthogonal to ample-normal curves

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Let XX be a projective manifold, let C⊂XC\subset X be a curve with ample normal sheaf, and let LL be a pseudo-effective line bundle. The numerical dimension ν(L)\nu(L) measures the numerical positivity of LL.

Numerical-dimension conjecture. If

L⋅C=0,L\cdot C=0,

then

ν(L)=0.\nu(L)=0.

This would describe the only expected obstruction to a curve with ample normal bundle lying in the interior of the movable cone. The paper proves that under the same orthogonality hypothesis one has κ(L)≤0\kappa(L)\leq 0, and relates the conjecture to the corresponding statement for divisors nef in codimension one; the full assertion remains open.

References

Primary source

Thomas Peternell, “Compact subvarieties with ample normal bundles, algebraicity and cones of cycles”, arXiv:1106.4433 (2011).

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