SELF MAPS OF P WITH PRESCRIBED RAMIFICATION IN CHARACTERISTIC p
نویسنده
چکیده
Using limit linear series and a result controlling degeneration from separable maps to inseparable maps, we give a formula for the number of selfmaps of P with ramification to order ei at general points Pi, in the case that all ei are less than the characteristic. Unlike the case of characteristic 0, the answer is not given by Schubert calculus, nor is the number of maps always finite for distinct Pi, even in the tamely ramified case. However, finiteness for general Pi, obtained by exploiting the relationship to branched covers, is a key part of the argument.
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