Regular formal modules in one-dimensional local fields

Аннотация

This paper considers the problem of the description of unramified extensions of a local field which, together with the main field, do not contain nontrivial roots of isogeny of the corresponding formal group defined over a ring of integers of this field. This problem originated from investigation of extensions without higher ramification for multiplicative formal groups in the paper by Z.I. Borevich (1962).