The generically nef tangent bundle conjecture for nef anticanonical manifolds

Let XX be a projective manifold, with tangent bundle TXT_X. A vector bundle is generically nef if its restriction to a general complete-intersection curve associated with a polarization is nef; it is sufficiently nef if through every point there is a covering family of curves on whose general member the bundle is nef. A projective manifold is rationally connected if any two general points can be joined by a rational curve.

Generically nef tangent bundle conjecture.

  1. If KX-K_X is nef, then TXT_X is generically nef.
  2. If KX-K_X is nef, then TXT_X is sufficiently nef.
  3. If XX is rationally connected, then TXT_X is generically ample, and hence sufficiently ample.

These assertions propose positivity properties of tangent bundles in two central classes of projective manifolds: those with nef anticanonical divisor and those that are rationally connected. The source presents them as conjectural, without giving a resolution.

Sources & referencesView supporting material

Primary source

Thomas Peternell, “Varieties with generically nef tangent bundles”, arXiv:0807.0982 (2008).

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