# セミナー

## 力学系セミナー

タイトル On the Ehrenfest wind-tree model 2018年7月27日 16:00 ～ 17:30 Serge Troubetzkoy 氏（Aix-Marseille University） 慶應義塾大学理工学部 14棟 733 (創想館 7階 ミーティング3) I will report on joint work with Alba Malaga Sabogal. In 1912 Paul Tatyana Ehrenfest proposed the wind-tree model in order to interpret the ergodic hypothesis of Boltzmann. In the Ehrenfest wind-tree model, a point particle (the wind’’) moves freely on the plane and collides with the usual law of geometric optics irregularly placed square scatterers (the trees’’). We show that for generic configurations (in the sense of Baire) the wind-tree model has very nice dynamics in a.e. direction: minimality, ergodicity, and infinite ergodic ind