%0 Journal Article
%T Canonical subgroups via Breuil-Kisin modules
%A Shin Hattori
%J Mathematics
%D 2010
%I arXiv
%R 10.1007/s00209-012-1102-0
%X Let p>2 be a rational prime and K/Q_p be an extension of complete discrete valuation fields. Let G be a truncated Barsotti-Tate group of level n, height h and dimension d over O_K with 0<d<h. In this paper, we show that an upper ramification subgroup G^j+ is free of rank d over Z/p^nZ if the Hasse invariant of G is less than 1/(2p^(n-1)). We also prove the usual properties as the canonical subgroup.
%U http://arxiv.org/abs/1012.1110v5