Schreier split extensions of preordered monoids

Gröbner-Shirshov bases for Schreier extensions of groups

In this paper, by using the Gröbner-Shirshov bases, we give characterizations of the Schreier extensions of groups when the group is presented by generators and relations. An algorithm to find the conditions of a group to be a Schreier extension is obtained. By introducing a special total order, we obtain the structure of the Schreier extension by an HNN group.

Extensions and submonoids of automatic monoids

On the Schreier Theory of Nonabelian Extensions: Generalisations and Computations

We use presentations and identities among relations to give a generalisation of the Schreier theory of nonabelian extensions of groups. This replaces the usual multiplication table for the extension group by more efficient, and often geometric, data. The methods utilise crossed modules and crossed resolutions.

Artin-schreier Extensions in Dependent and Simple Fields

We show that dependent elds have no Artin-Schreier extension, and that simple elds have only a nite number of them.

Ramification groups in Artin - Schreier - Witt extensions par Lara

Let K be a local field of characteristic p > 0. The aim of this paper is to describe the ramification groups for the prop abelian extensions over K with regards to the Artin-SchreierWitt theory. We shall carry out this investigation entirely in the usual framework of local class field theory. This leads to a certain non-degenerate pairing that we shall define in detail, generalizing in this way...