Relationships between Model Theory and Valuations of Fields

Abstract

This thesis explores some of the relationships between model theoretic and algebraic properties of fields, focusing on valuations of fields. We first show that the dp-rank of henselian valued fields admitting relative quantifier elimination is equal to the sum of the dp-ranks of the value group and of the residue field. Moreover, we give a characterization of henselianity of valued fields of finite dp-rank in terms of the dp-rank of definable sets. We also obtain partial results generalizing the work of Johnson in classifying fields of finite dp-rank. Finally, we consider fields with the property that the algebraic closure is an immediate extension with respect to every valuation. We show that under certain conditions these fields are dense in their algebraic closure with respect to every valuation and provide an example that demonstrates that this property does not hold in general.