Andrzej Zuk (Université Paris 7, и Кафедра Ламе, СПбГУ)
Специальная лекция лаборатории им. Чебышева
Пятница 20 апреля 17:00 ауд. 14 (14-я линия В. О., 29)
In 1924 Banach and Tarski proved that a ball in 3‑dimensional space can be decomposed into finitely many pieces which one could reassemble by rotations to form two copies of the original ball. We relate this to two fundamental notions in group theory: amenability (introduced by von Neumann) and property (T) (defined by Kazhdan).
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