Model theory of differential-henselian pre--fields
arXiv:1910.12171 · doi:10.1017/jsl.2025.28
Abstract
Pre--fields are ordered valued differential fields satisfying some basic axioms coming from transseries and Hardy fields. We study pre--fields that are differential-Hensel-Liouville closed, that is, differential-henselian, real closed, and closed under exponential integration, establishing an Ax--Kochen/Ershov theorem for such structures: the theory of a differential-Hensel-Liouville closed pre--field is determined by the theory of its ordered differential residue field; this result fails if the assumption of closure under exponential integration is dropped. In a two-sorted setting with one sort for a differential-Hensel-Liouville closed pre--field and one sort for its ordered differential residue field, we eliminate quantifiers from the pre--field sort, from which we deduce that the ordered differential residue field is stably embedded and if it has NIP, then so does the two-sorted structure. Similarly, the one-sorted theory of differential-Hensel-Liouville closed pre--fields with closed ordered differential residue field has quantifier elimination, is the model completion of the theory of pre--fields with gap~, and is complete, distal, and locally o-minimal.
37 pages; v7: minor corrections and adjustments