We study the notion of dp-minimality, beginning by providing several essential facts about dp-minimality, establishing several equivalent definitions for dp-minimality, and comparing dp-minimality to other minimality notions. The majority of the rest of the paper is dedicated to examples. We establish via a simple proof that any weakly o-minimal theory is dp-minimal and then give an example of a weakly o-minimal group not obtained by adding traces of externally definable sets. Next we give an example of a divisible ordered Abelian (...) group which is dp-minimal and not weakly o-minimal. Finally we establish that the field of p -adic numbers is dp-minimal. (shrink)

Let ℱ be the class of complete, finitely axiomatizable ω-categorical theories. It is not known whether there are simple theories in ℱ. We prove three results of the form: if T∈ ℱ has a sufficently well-behaved definable set J, then T is not simple. All of our arguments assume that the definable set J satisfies the Mazoyer hypothesis, which controls how an element of J can be algebraic over a subset of the model. For every known example in ℱ, there (...) is a definable set satisfying the Mazoyer hypothesis. (shrink)

Clark and Krauss [1977] presents a classification of complete, satisfiable and o-categorical theories in first order languages with finite non-logical vocabularies. In 1988 the first author modified this classification and raised three questions about the distribution of finitely axiomatizable theories. This paper answers two of those questions.