Tame-blind extension of morphisms of truncated Barsotti-Tate group schemes

J. Math. Sci. Univ. Tokyo
Vol. 16 (2009), No. 1, Page 23--54.

Hoshi, Yuichiro
Tame-blind extension of morphisms of truncated Barsotti-Tate group schemes
The purpose of the present paper is to show that morphisms between the generic fibers of truncated Barsotti-Tate group schemes over mixed characteristic complete discrete valuation rings extend in a tame-blind'' fashion --- i.e., under a condition which is unaffected by passing to a tame extension --- to morphisms between the original truncated Barsotti-Tate group schemes. The tame-blindness'' of our extension result allows one to verify the analogue of the result of Tate for isogenies of Barsotti-Tate groups over the ring of integers of the $p$-adic completion of the maximal tamely ramified extension.