Extension bases in Henselian valued fields

Abstract

We study the behaviour of forking in valued fields, and we give several sufficient conditions for parameter sets in a Henselian valued field of residue characteristic zero to be an extension base. Notably, we consider arbitrary (potentially imaginary) bases, whereas previous related results in the literature only focus on maximally complete sets of parameters. This enables us in particular to show that forking coincides with dividing in (the imaginary expansions of) the ultraproducts of the p-adic fields.