\documentclass[a4paper]{article} \usepackage{amssymb} \pagestyle{empty} \hoffset=-40pt \voffset=-20pt \textwidth 15.3cm \textheight 22cm % to fit our printers \begin{document} \begin{center}{\huge On topological stability conjecture}\end{center} \begin{center}{\large Ludomir Newelski (Wroclaw)}\end{center} \bigskip The subject is related to Vaught's conjecture. Assume $T$ is a complete theory, $M$ is a countable model of $T$ and $Q$ is a $0$-definable subset of $M$. Then ${\rm Aut}(Q)$ acts on $S(Q)$, the orbits are called pseudo-types. Notice that this is a Borel action of a Polish group on a Polish space, and the orbits are Borel, too. The topological stability conjecture asserts that if $T$ has < continuum countable models, then all (good) pseudo-types are ``topologically nice'' ($t$-stable). I proved several special cases of this conjecture, mainly for stable and superstable theories. These special cases have interesting consequences, which I will discuss. \end{document}