Izadi's base-locus conjecture for Prym second-order theta divisors

Let (P,Ξ)(P,\Xi) be a Prym variety associated with a double cover π:C~C\pi:\widetilde C\to C, and let Σ\Sigma be the relevant Prym-theta subvariety. Let Γ00\Gamma_{00}' consist of sections in Γ00\Gamma_{00} whose restriction to Σ\Sigma vanishes, let 2Ξ00|2\Xi|_{00}' be its projectivized linear system, and let V00V_{00}' be its base locus. Let Q00{\cal Q}_{00}' be the corresponding system of quartic tangent cones at the origin, with base locus Vinf,00V_{\inf,00}'. Let χC\chi C denote the Prym-canonical image of CC in ωCα|\omega_C\otimes\alpha|^*, where α\alpha is the square-trivial invertible sheaf associated with π\pi. Izadi's Prym base-locus conjecture. If (P,Ξ)(P,\Xi) is not a Jacobian, then

  1. V00=ΣV_{00}'=\Sigma as a set if p6p\geq 6;
  2. Vinf,00=χCV_{\inf,00}'=\chi C as a set if p6p\geq 6.

This conjecture asks whether the restricted second-order theta systems detect precisely the Prym-theta subvariety and its Prym-canonical tangent-cone curve away from the Jacobian locus. The source poses it after proving dimension and codimension bounds; no resolution is specified here.

Sources & referencesView supporting material

Primary source

E. Izadi, “Second order theta divisors on Pryms”, arXiv:alg-geom/9704020 (1997).

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