Definable actions, weakly almost periodic actions, and continuous logic stability (joint work with E. Hrushovski and K. Krupiński)

Seminarium: 
Teoria modeli
Osoba referująca: 
Anand Pillay (University of Notre Dame)
Data: 
środa, 21. Listopad 2018 - 16:15
Sala: 
604
Opis: 
We show the connection between definability of an action of a definable group in a structure M on a compact space X, the notion of weakly almost periodic actions, and stability in continuous logic. As a consequence show that if M is sufficiently saturated and we are given a definable action of a group G definable in M on a compact space X, then X supports a G-invariant (Borel probability) measure. This yields to a negative answer to a question of Krupiński.