2010/04/19 by Yanhong Yang, Yang, Yanhong
Mathematics · Physics and Astronomy · #Advanced Algebra and Geometry #Algebraic structures and combinatorial models #Nonlinear Waves and Solitons #math.AG #msc:11F80 #msc:14F30 #msc:14H30
paper · pdf · doi:10.48550/arxiv.1004.3090
arxiv created 2010/04/19 · arxiv updated 2010/04/20
Consider an F-crystal over a noetherian scheme S. De Jong--Oort's purity theorem states that the associated Newton polygons over all points of S are constant if this is true outside a subset of codimension bigger than 1. In this paper we show an improvement of the theorem, which says that the Newton polygons over all points of S have a common break point if this is true outside a subset of codimension bigger than 1.