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arXiv · 1309.7229

Extremal divisors on moduli spaces of rational curves with marked points

Morgan Opie
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Abstract

We study effective divisors on $\overline{M}_{0,n}$, focusing on hypertree divisors introduced by Castravet and Tevelev and the proper transforms of divisors on $\overline{M}_{1,n-2}$ introduced by Chen and Coskun. Results include a database of hypertree divisor classes and closed formulas for Chen--Coskun divisor classes. We relate these two types of divisors, and from this construct extremal divisors on $\overline{M}_{0,n}$ for $n \geq 7$ that furnish counterexamples to the conjectural description of the effective cone of $\overline{M}_{0,n}$ given by Castravet and Tevelev.

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Morgan Opie. 2013-09-27. Extremal divisors on moduli spaces of rational curves with marked points. https://arxiv.org/abs/1309.7229

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