Israel Journal of Mathematics

, Volume 164, Issue 1, pp 303–315

Jacobians with a vanishing theta-null in genus 4


    • Mathematics DepartmentPrinceton University
  • Riccardo Salvati Manni
    • Dipartimento di MatematicaUniversità “La Sapienza”

DOI: 10.1007/s11856-008-0031-4

Cite this article as:
Grushevsky, S. & Salvati Manni, R. Isr. J. Math. (2008) 164: 303. doi:10.1007/s11856-008-0031-4


In this paper we prove a conjecture of Hershel Farkas [11] that if a 4-dimensional principally polarized abelian variety has a vanishing theta-null, and the Hessian of the theta function at the corresponding 2-torsion point is degenerate, the abelian variety is a Jacobian.

We also discuss possible generalizations to higher genera, and an interpretation of this condition as an infinitesimal version of Andreotti and Mayer’s local characterization of Jacobians by the dimension of the singular locus of the theta divisor.

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© The Hebrew University of Jerusalem 2008