English

Gonality of curves on general hypersurfaces

Algebraic Geometry 2019-04-15 v2

Abstract

This paper concerns the existence of curves with low gonality on smooth hypersurfaces of sufficiently large degree. It has been recently proved that if XPn+1X\subset \mathbb{P}^{n+1} is a hypersurface of degree dn+2d\geq n+2, and if CXC\subset X is an irreducible curve passing through a general point of XX, then its gonality verifies gon(C)dn\mathrm{gon}(C)\geq d-n, and equality is attained on some special hypersurfaces. We prove that if XPn+1X\subset \mathbb{P}^{n+1} is a very general hypersurface of degree d2n+2d\geq 2n+2, the least gonality of an irreducible curve CXC\subset X passing through a general point of XX is gon(C)=d16n+112\mathrm{gon}(C)=d-\left\lfloor\frac{\sqrt{16n+1}-1}{2}\right\rfloor, apart from a series of possible exceptions, where gon(C)\mathrm{gon}(C) may drop by one.

Keywords

Cite

@article{arxiv.1707.07252,
  title  = {Gonality of curves on general hypersurfaces},
  author = {Francesco Bastianelli and Ciro Ciliberto and Flaminio Flamini and Paola Supino},
  journal= {arXiv preprint arXiv:1707.07252},
  year   = {2019}
}

Comments

24 pages. We corrected various inaccuracies pointed out by the referee