English

Conic-connected Manifolds

Algebraic Geometry 2012-09-11 v3

Abstract

We study a particular class of rationally connected manifolds, X\pNX\subset \p^N, such that two general points x,xXx,x' \in X may be joined by a conic contained in XX. We prove that these manifolds are Fano, with b22b_2\leq 2. Moreover, a precise classification is obtained for b2=2b_2=2. Complete intersections of high dimension with respect to their multi-degree provide examples for the case b2=1b_2=1. The proof of the classification result uses a general characterization of rationality, in terms of suitable covering families of rational curves.

Keywords

Cite

@article{arxiv.math/0701885,
  title  = {Conic-connected Manifolds},
  author = {Paltin Ionescu and Francesco Russo},
  journal= {arXiv preprint arXiv:math/0701885},
  year   = {2012}
}

Comments

12 pages; v2: Theorem 1.3 with weaker formulation; more refined version of Theorem 1.5 (new numbering); more details proof Main Theorem 2.2;v3: Proposition 2.4 added. Final version to appear in Crelle's Journal