The Final Log Canonical Model of the Moduli Space of Stable Curves of Genus Four
نویسنده
چکیده
We describe the GIT quotient of the linear system of (3, 3) curves on P × P as the final non-trivial log canonical model of M4, isomorphic to M4(α) for 8/17 < α ≤ 29/60. We describe singular curves parameterized by M4(29/60), and show that the rational map M4 99K M4(29/60) contracts the Petri divisor, in addition to the boundary divisors ∆1 and ∆2. This answers a question of Farkas.
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