×

Approximation properties for orderings on \({}^*\)-fields. (English) Zbl 0706.12005

Summary: The goal of this paper is to extend the main theorems on approximation properties of the topological space of orderings from formally real fields to skew fields with an involution \({}^*\). To accomplish this the concept of \({}^*\)-semiordering is developed and new theorems are obtained for lifting \({}^*\)-orderings from the residue class field of a real valuation.

MSC:

12J15 Ordered fields
16K40 Infinite-dimensional and general division rings
12E15 Skew fields, division rings
16W10 Rings with involution; Lie, Jordan and other nonassociative structures
12D15 Fields related with sums of squares (formally real fields, Pythagorean fields, etc.)
Full Text: DOI