Double Points of Plane Models in Mg,1
Abstract
The aim of this paper is to compute the class of the closure of the effective divisor in M6,1 given by pointed curves [C,p] with a sextic plane model mapping p to a double point. Such a divisor generates an extremal ray in the pseudoeffective cone of M6,1 as shown by Jensen. A general result on some families of linear series with adjusted Brill-Noether number 0 or -1 is introduced to complete the computation.
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