比利时vs摩洛哥足彩
,
university of california san diego
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math 209 - number theory
andrew obus
columbia university
good reduction of three-point galois covers
abstract:
we study galois covers of the projective line branched at three points with galois group $g$. when such a cover is defined over a $p$-adic field, it is known to have potentially good reduction to characteristic $p$ if $p$ does not divide the order of $g$. we give a sufficient criterion for good reduction, even when $p$ does divide the order of $g$, so long as the $p$-sylow subgroup of $g$ is cyclic and the absolute ramification index of a field of definition of the cover is small enough. this extends work of (and answers a question of) raynaud. our proof depends on working very explicitly with kummer extensions of complete discrete valuation rings with imperfect residue fields.
host: kiran s. kedlaya
january 16, 2013
3:00 pm
ap&m 7218
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