On Numerical Nonvanishing for Generalized Log Canonical Pairs

  • Jingjun Han

    Department of Mathematics, Johns Hopkins University, Baltimore, MD 21218, USA
  • Wenfei Liu

    School of Mathematical Sciences, Xiamen University, Fujian 361005, P. R. China
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Abstract

The nonvanishing conjecture for projective log canonical pairs plays a key role in the minimal model program of higher dimensional algebraic geometry. The numerical nonvanishing conjecture considered in this paper is a weaker version of the usual nonvanishing conjecture, but valid in the more general setting of generalized log canonical pairs. We confirm it in dimension two. Under some necessary conditions we obtain effective versions of numerical nonvanishing for surfaces. Several applications are also discussed.

In higher dimensions, we mainly consider the conjecture for generalized klt pairs , and reduce it to lower dimensions when is not pseudo-effective. Up to scaling the nef part, we prove the numerical nonvanishing for pseudo-effective generalized lc threefolds with rational singularities.

Cite this article

Jingjun Han, Wenfei Liu, On Numerical Nonvanishing for Generalized Log Canonical Pairs. Doc. Math. 25 (2020), pp. 93–123

DOI 10.4171/DM/739