On the $S_n$-invariant F-conjecture

Abstract

By using classical invariant theory, we reduce the $S_n$-invariant F-conjecture to a feasibility problem in polyhedral geometry. We show by computer that for $n\le 19$, every integral $S_n$-invariant F-nef divisor on the moduli space of genus zero stable pointed curves is semi-ample, over arbitrary characteristic. Furthermore, for $n\le 16$, we show that for every integral $S_n$-invariant nef (resp. ample) divisor $D$ on the moduli space, $2D$ is base-point-free (resp. very ample). As applications, we obtain the nef cone of the moduli space of stable curves without marked points, and the semi-ample cone that of the moduli space of genus 0 stable maps to Grassmannian for small numerical values.

14 pages. The proof of the base-point-freeness result (Theorem 6.2) of the earlier version had a gap

References in corpus (1)

• A simplicial approach to effective divisors in ${\overline{M}}_{0,n}$