English

Rational connectedness modulo the Non-nef locus

Algebraic Geometry 2009-01-29 v1

Abstract

It is well known that a smooth projective Fano variety is rationally connected. Recently Zhang (and later Hacon and McKernan as a special case of their work on the Shokurov RC-conjecture) proved that the same conclusion holds for a klt pair (X,\D)(X,\D) such that (KX+\D)-(K_X+\D) is big and nef. We prove here a natural generalization of the above result by dropping the nefness assumption. Namely we show that a klt pair (X,\D)(X,\D) such that (KX+\D)-(K_X+\D) is big is rationally connected modulo the non-nef locus of (KX+\D)-(K_X+\D). This result is a consequence of a more general structure theorem for arbitrary pairs (X,\D)(X,\D) with (KX+\D)-(K_X+\D) pseff.

Keywords

Cite

@article{arxiv.0901.4494,
  title  = {Rational connectedness modulo the Non-nef locus},
  author = {Amaël Broustet and Gianluca Pacienza},
  journal= {arXiv preprint arXiv:0901.4494},
  year   = {2009}
}
R2 v1 2026-06-21T12:05:35.261Z