Ward Henson (UIUC, UC Berkeley) On definability and interpretability in model theory Abstract: This will be an expository talk. Topics covered/mentioned will include: extension by definition and expansion/extension by interpretation (the eqconstruction), Beth's Theorem (characterizing definability), and Makkai's Theorem (characterizing the eqexpansion). The setting will be model theory of classical (discrete) structures and then of metric (realvalued) structures. In the metric setting, definability of sets/relations has some subtleties that do not arise in discrete structures. 
