Séminaire de théorie des groupes à l’ENS

Le séminaire sera dans salle W et retransmis sur Zoom : https://https://us02web.zoom.us/j/81313173812 Meeting ID: 813 1317 3812 Mot de passe: G est un Graphe de Cayley du groupe libre à 107 générateurs. Quel est le degré de ce graphe? Tapez le numéro à trois chiffres comme un mot de passe. 14.00-14.45 Yves Benoist (Orsay), Harmonic functions on the Heisenberg group 15.00-15.45 Nora Szakacs (Manchester), Inverse semigroups as metric spaces, and their uniform Roe algebras. 16.00-16.45 Richard Aoun (Marne-la-Vallée), Concentration inequalities for random walks on hyperbolic spaces, and applications.

Le séminaire sera dans salle W et retransmis sur Zoom : https://us02web.zoom.us/j/83940344109 Meeting ID: 839 4034 4109 Mot de passe: G est un Graphe de Cayley du groupe libre à 107 générateurs. Quel est le degré de ce graphe? Tapez le numéro à trois chiffres comme un mot de passe. 14.00-14.45 Emmanuel Breuillard (Oxford), Random character varieties. 15.00-15.45 Pierre Py (Strasbourg), Subgroups of hyperbolic groups, finiteness properties and complex hyperbolic lattices. 16.00-16.45 Olga Kharlampovich (Graduate Center and Hunter College CUNY), Equations and first-order sentences in random groups.

Le séminaire sera dans salle W et retransmis sur Zoom : https://us02web.zoom.us/j/83495836865 Meeting ID: 834 9583 6865 Mot de passe: G est un Graphe de Cayley du groupe libre à 107 générateurs. Quel est le degré de ce graphe? Tapez le numéro à trois chiffres comme un mot de passe. 14.00 -- 14.45 Alex Eskin (University of Chicago), On a theorem of Furstenberg 15.00 -- 15.45 (CANCELLED!) Alex Gamburd (Graduate Center, CUNY), Arithmetic and Dynamics on Varieties of Markoff Type 15.00 -- 15.45 Vadim Kaimanovich (University of Ottawa), Limit distributions […]

Le séminaire sera dans salle W et retransmis sur Zoom : https://us02web.zoom.us/j/82734674940 Meeting ID: 827 3467 4940 Mot de passe: G est un Graphe de Cayley du groupe libre à 107 générateurs. Quel est le degré de ce graphe? Tapez le numéro à trois chiffres comme un mot de passe.   14.00 -- 14.45 Jingyin Huang (Ohio State University), Labeled four wheels and the K(pi,1) problem for reflection arrangement complements 15.00 -- 15.45 Corentin Bodard (University of Geneva), Intermediate geodesic growth in virtually nilpotent groups 16.00 -- 16.45 Lopez Neumann […]

14.00 -- 14.45 Timothée Bénard (University of Warwick), "Limit theorems on nilpotent Lie groups". 15.00 -- 15.45 Panagiotis Tselekidis (ENS Paris),  "Asymptotic dimension of finitely generated groups". 16.15 -- 17.00 Andrey Alpeev (ENS Paris), "Invariant random order extension and amenability".

Nomember 15 (wednesday, unusual day)   14.00-14.45 Simon André (Paris VI)  "Sharply 2-transitive infinite finitely generated simple groups". 15.00-15.45  Ruiwen Dong (Saarland University)  "Decision problems in sub-semigroups of metabelian groups". 16.00-16.45  Emmanuel Rauzy (Munich University)  "Groups with presentations in EDT0L".   Simon André  "Sharply 2-transitive infinite finitely generated simple groups". A group G is said to be sharply 2-transitive if it has an action on a set X with at least 2 elements such that, for all pairs (x, x') and (y, y') of distinct elements in X, there exists […]

December  13 (wednesday, unusual day) 14.00--14.45 Reem Yassawi (Queen Mary University of London) "Tame or wild Toeplitz shifts" 15.00--15.45 Todor Tsankov (Lyon 1) "Gleason complete flows of locally compact groups" 16.15--17.00 Johannes Kellendonk (Lyon 1) "Which algebraic components of the Ellis semigroup of a non-tame dynamical system are especially big?" Reem Yassawi     "Tame or wild Toeplitz shifts" The Ellis semigroup E(X, T) of a topological dynamical system is defined to be the compactification of the action T in the topology of pointwise convergence on the space of all […]

January 31 (wednesday)   14.00 - 14.45 Valérie Berthé (Paris VII),  "Dendric subshifts  and groups" 15.00 - 15.45  Nguyen-Bac Dang, (Orsay) , "Variation of the Hausdorff dimension of limits set and degenerating Schottky groups" 16.15 - 17.00  Bruno Duchesne (Orsay), TBA   Valérie Berthé,   "Dendric subshifts  and groups"   We discuss a family of  symbolic dynamical systems  that have remarkable  group properties, the family of dendric words. This family  includes numerous classical families of   symbolic dynamical systems,   among others codings of interval exchanges. Their return words  form […]

March 12 (Tuesday) This seminar meeting will focus on interactions between groups and random walks, and will be dedicated to our beloved mentor and colleague, Anatoly Moiseevich Vershik, who pioneered this field.   14.00 - 14.45 Cyril Houdayer (ENS Paris)  ``The noncommutative factor theorem for lattices in product groups''. 15.00 - 15.45   Kunal Chawla (Princeton)   "The Poisson boundary of hyperbolic groups without moment conditions". 16.15 - 17.00   Sara Brofferio (Université Paris-Est Créteil Val-de-Marne),  "Uniqueness of  invariant measures for random homeomorphisms of the real line". ----   Cyril Houdayer  […]

April 16 (Tuesday) For this seminar we will have the pleasure of listening to three talks: 14.00 - 14.45 Andrei Jaikin-Zapirain (UAM), "Compressed subgroups in free groups are inert" 15.00 - 15.45 Timothée Marquis (UCL), "Amalgams of rational unipotent groups and residual nilpotence". 16.15 - 17.00 Olga Kharlampovich (CUNY), "Quantification of separability of cubically convex-cocompact subgroups of RAAGs via representations".  Andrei Jaikin-Zapirain  "Compressed subgroups in free groups are inert".   Let F be a free group. A finitely generated subgroup H is called compressed in F if it is not contained […]

An afternoon on random walks on groups. 14.00 - 14.45   Giulio Tiozzo (Toronto) ``Roots of Alexander polynomials of random positive braids'';   15.00 - 15.45   Amaury Freslon (Orsay)  ``How to (badly) shuffle cards?''; 16.15 - 17.00   Charles Bordenave (Marseille) ``Strong convergence of matrix algebras and applications to random walks''.   Giulio Tiozzo  ``Roots of Alexander polynomials of random positive braids'' As originally observed experimentally by Dehornoy, roots of Alexander polynomials of random knots display interesting patterns. In this work, joint with N. Dunfield, we prove several results […]