Commentaires pour Notes

Commentaires sur Groupes de Coxeter (notes de Stéphane Lamy préparées pour ses exposés) par Immeubles sphériques des groupes algébriques semisimples | Notes

Immeubles sphériques des groupes algébriques semisimples | Notes — Tue, 19 Mar 2019 16:58:41 +0000

[…] O(V) ) engendré par les réflexions ( s_alpha ). Par la théorie générale exposée dans les notes de Stéphane il existe un sous-ensemble ( Delta subset Phi ) ayant les propriétés suivantes […]

Commentaires sur The Neretin groups (Bruno Duchesne) par Lectures on the Stück–Zimmer Theorem | Notes

Lectures on the Stück–Zimmer Theorem | Notes — Thu, 14 Jun 2018 14:39:42 +0000

[…] Note that all examples above are ergodic, but none is properly ergodic, that is all are supported on a single conjugacy class. Properly ergodic IRSs do exist in some groups. The constructions above show that whenever a lcsc group ( G ) either is not simple, or has a proper nontrivial cofinite subgroup it has IRSs beyong the « trivial » ones ( delta_G ) and ( delta_{mathrm{Id}} ). There are discrete (Thompson groups) and non-discrete (see Adrien le Boudec’s talk) examples of totally disconnected groups where these are the only ergodic IRSs. There is however no known example of a nondiscrete, compactly generated group where this propert of « non nontrivial IRSs » holds. A candidate for this is the Neretin group, which we discuss in another series of lectures. […]

Commentaires sur Lectures on the Stuck–Zimmer Theorem par Locally compact groups whose ergodic or minimal actions are all free (Adrien le Boudec, joint work with Nicolas Matte-Bon) | Notes

Thu, 14 Jun 2018 14:37:21 +0000

[…] of ( G ) and the space ( mathrm{IRS}(G) ) of invariant random subgroups of ( G ) in the lectures on the Nevo–Stück–Zimmer theorem. A corresponding topological notion is given by the following objects introduced by Eli Glasner and […]

Commentaires sur Locally compact groups whose ergodic or minimal actions are all free (Adrien le Boudec, joint work with Nicolas Matte-Bon) par Lectures on the Stück–Zimmer Theorem | Notes

Lectures on the Stück–Zimmer Theorem | Notes — Thu, 14 Jun 2018 14:36:39 +0000

[…] ) and ( delta_{mathrm{Id}} ). There are discrete (Thompson groups) and non-discrete (see Adrien le Boudec’s talk) examples of totally disconnected groups where these are the only ergodic IRSs. There is however no […]

Commentaires sur Lp-cohomology (Marc Bourdon) par Measured group theory (Uri Bader) | Notes

Measured group theory (Uri Bader) | Notes — Sat, 19 Aug 2017 09:50:03 +0000

[…] numbers of ME-equivalent groups. A corollary which is easier to state is the following (see Marc Bourdon’s lectures for the definition of the reduced ( ell_2 )-cohomology groups ( overline H^k(cdot, […]

Commentaires sur Ingredients and consequences of quasi-isometric rigidity of lattices in certain solvable Lie groups (Tullia Dymarz) par Lp-cohomology (Marc Bourdon) | Notes

Lp-cohomology (Marc Bourdon) | Notes — Wed, 02 Aug 2017 09:58:18 +0000

[…] saw in Tullia Dymarz’s lectures that negatively curved homogeneous spaces are obtained as Heintze groups, for example: [ G = […]

Commentaires sur Quasi-isometric rigidity of nonuniform lattices (Misha Kapovich) par Ingredients and consequences of quasi-isometric rigidity of lattices in certain solvable Lie groups (Tullia Dymarz) | Notes

Fri, 14 Jul 2017 16:52:16 +0000

[…] the definition of a ( (K, C) )-quasi-isometry of ( X ) from Kapovich’s lectures: it is a map ( X to X ) which is a ( (K, C) )-quasi-isometruc embedding, that is [ frac 1 K […]

Commentaires sur L2-invariants and 3–manifolds, II (Stefan Friedl) par ( L^2 )-Alexander torsions of 3–manifolds (Yi Liu) | Notes

( L^2 )-Alexander torsions of 3–manifolds (Yi Liu) | Notes — Sat, 15 Oct 2016 12:57:23 +0000

[…] In the case where ( G = {mathbb Z}^m ) is a free Abelian group then the Fuglede-Kadison determinant can be computed to be the Mahler measure of the classical determinant. In particular, when ( G = {mathbb Z} ) and for the complex in ( (ast) ) above the ( L^2 )-Alexander torsion is given by: [ tau^{(2)}(N; phi, phi) = Ct^d prod_{i=1}^d max(1, t^{-1}|z_i|) ] where the ( z_i ) are roots of the polynomial ( det(phi(A)) ) (see Stefan Friedl’s second lecture). […]

Commentaires sur The center-valued Atiyah conjecture (Thomas Schick) par Alexander and Thurston norms, and the Bieri–Neumann–Strebel invariants for free-by-cyclic groups (Dawid Kielak, notes by Steffen Kionke) | Notes

Sat, 15 Oct 2016 12:23:31 +0000

[…] Let ( G ) have a finite, ( L^2 )-acyclic ( K(G, 1) ), and in addition satisfy the Atiyah conjecture. Let ( {mathbb Z} G subset mathcal DG ) be the division closure of ( {mathbb Z} G ) in the algebra of affiliated operators (see Thomas Schick’s talk). […]

Commentaires sur L2-invariants of locally symmetric spaces, II (Nicolas Bergeron) par Notes » L2-invariants of locally symmetric spaces, III (Nicolas Bergeron)

Notes » L2-invariants of locally symmetric spaces, III (Nicolas Bergeron) — Sun, 09 Oct 2016 13:46:59 +0000

[…] applications to the growth of torsion homology via the Cheeger–Müller theorem one needs in addition to control the regulators ( overline R^q ), which might be feasible only […]