1. The algebra and model theory of tame valued fields
- Author
-
Franz-Viktor Kuhlmann
- Subjects
Algebraic function field ,Applied Mathematics ,General Mathematics ,010102 general mathematics ,Normal extension ,Field (mathematics) ,Commutative Algebra (math.AC) ,Mathematics - Commutative Algebra ,01 natural sciences ,Algebraic closure ,Algebra ,Residue field ,Algebraic theory ,0103 physical sciences ,FOS: Mathematics ,12J10, 12J15 ,010307 mathematical physics ,0101 mathematics ,Algebraically closed field ,Valuation (algebra) ,Mathematics - Abstract
A henselian valued field K is called a tame field if its algebraic closure K ~ ${\tilde{K}}$ is a tame extension, that is, the ramification field of the normal extension K ~ | K ${\tilde{K}|K}$ is algebraically closed. Every algebraically maximal Kaplansky field is a tame field, but not conversely. We develop the algebraic theory of tame fields and then prove Ax–Kochen–Ershov Principles for tame fields. This leads to model completeness and completeness results relative to value group and residue field. As the maximal immediate extensions of tame fields will in general not be unique, the proofs have to use much deeper valuation theoretical results than those for other classes of valued fields which have already been shown to satisfy Ax–Kochen–Ershov Principles. The results of this paper have been applied to gain insight in the Zariski space of places of an algebraic function field, and in the model theory of large fields.
- Published
- 2014