arXiv subjects

Jonathan Lubin

Publications and source records attributed to Jonathan Lubin.

2 recordsLinked to original sources

arXiv2014

A characterization of strictly APF extensions

Let K denote a finite extension of Qp. We give necessary and sufficient conditions for an infinite totally wildly ramified extension L/K to be strictly APF in the sense of Fontaine-Wintenberger. Our conditions are phrased in terms of the existence of a certain tower of intermediate subfields. These conditions are well-suited to producing examples of strictly APF extensions, and in particular, our main theorem proves that the phi-iterate extensions previously considered by the first two authors are strictly APF.

math.NT↗

arXiv2006

Raynaud's group-scheme and reduction of coverings

The structure of the reduction of an admissible $G$-covering $Y \to X$ at primes $p$ dividing $|G|$ is investigated. Assume $|G|$ is not divisible by $p^2$ and the $p$-Sylow group is normal. Following Raynaud it is shown that there is a group scheme $\cG$ over the smooth locus of $X$ for which $Y$ is still a principal bundle away from the special points. A structure at the nodes involving Artin twisted curves is discussed.

math.AG↗