English

Abundance for uniruled pairs which are not rationally connected

Algebraic Geometry 2025-08-22 v4

Abstract

One of the central aims of the Minimal Model Program is to show that a projective log canonical pair (X,Δ)(X,\Delta) with KX+ΔK_X+\Delta pseudoeffective has a good model, i.e.\ a minimal model (Y,ΔY)(Y,\Delta_Y) such that KY+ΔYK_Y+\Delta_Y is semiample. The goal of this paper is to show that this holds if XX is uniruled but not rationally connected, assuming the Minimal Model Program in dimension dimX1\dim X-1. Moreover, if XX is rationally connected, then we show that the existence of a good minimal model for (X,Δ)(X,\Delta) follows from a nonexistence conjecture for a very specific class of rationally connected pairs of Calabi--Yau type.

Keywords

Cite

@article{arxiv.1908.06945,
  title  = {Abundance for uniruled pairs which are not rationally connected},
  author = {Vladimir Lazić},
  journal= {arXiv preprint arXiv:1908.06945},
  year   = {2025}
}

Comments

v4: Theorems 2.1 and 2.2 added; to appear in Enseign. Math