In order to generalize Poizat's theory of belle paires to unstable theories, one needs to assume the amalgamation property for the class of global definable types. In the talk, we will highlight this connection, exhibit some important classes of theories in which definable types may be amalgamated, and exhibit an example of a theory in which they don't. This talk is based on joint work with Pablo Cubides and Jinhe Ye, and with Rosario Mennuni.
Keywords: model theory; definable type; beautiful pair; amalgamation property