The Geometry of Linear Regular Types

Abstract

This paper is concerned with extending results from "The Geometry of 1-Based Minimal Types" by Kim and the present author. We work in the more general context of the solution set D of a regular Lascar Strong Type defined over the empty set in a simple theory T. In Pillay's book "Geometric Stability Theory", a notion of p-weight is developed for regular types in stable theories. Here we show that the corresponding notion holds in simple theories and give a geometric analysis of associated structures G(D) and G(D)(large), the former of which appears in the above paper. We show that D is linear iff G(D) and G(D)(large) (localized, respectively) are both modular with respect to the p-closure operator. Finally, we show that modularity of G(D)(large) provides a local analogue of 1-basedness for the theory T.