Recordings

"Midrasha on Groups" lectures, 2024 - 2025

 

Fall Semester

Here is a link to the playlist of all the talks in the learning seminar Measured Group Theory.

For talks in the afternoon sessions go to this link

Recordings which do not appear in the above playlists may be available upon request.

 

"Midrasha on Groups" lectures, 2023 - 2024

Prof. Uri Bader and Prof. Alex Lubotzky 
 

Spring Semester

Here is a link to the playlist of all the talks in the learning seminar On Expanders, Ramanujan Graphs, Property Testing, Stability, and Group Approximation.

For research talks in the morning sessions go to this link

Recordings which do not appear in the above playlists may be available upon request. 

Autumn Semester

Here is a link to the playlist of all the talks in the learning seminar The Spectrum of Hyperbolic Surfaces.

For talks in the afternoon sessions go to this link

Recordings which do not appear in the above playlists may be available upon request. 

"Midrasha on Groups" lectures, 2022 - 2023

Prof. Uri Bader and Prof. Alex Lubotzky 

Spring Semester

Midrasha lecture 26.6.23

Yuval Grofine (Weizmann) - Ends of hyperbolic Manifolds (based on Benedetti and Petronio’s book, pages 143–159). Recording

Yair Hartman (BGU) - Stationary Random Subgroups. Recording

Midrasha lecture 26.6.23

  • Polina Zakorko (Weizmann) - Margulis’ Lemma and the local geometry of a hyperbolic manifold (based on Benedetti and Petronio’s book, pages 133–143). Recording

  • Benjamin Bachner (Weizmann) - Stability of groups in the rank metric. Recording

     

Midrasha lecture 12.6.23

  • Michael Glasner (Weizmann) - The Rigidity Theorem: the Gromov norm and the volume are proportional (based on Benedetti and Petronio’s book, pages 105–121). Recording

  • Amir Behar (HUJI) - Profinite non-rigidity of arithmetic groups. Recording

Midrasha lecture 5.6.23

  • Idan Pazi (Weizmann) - The Rigidity Theorem volume of ideal simplices and the Gromov norm (based on Benedetti and Petronio’s book, pages 94–105). Recording

  • Bharat Rangarjan (HUJI) - Asymptotic bounded cohomology and uniform stability of high rank lattices. Recording

Midrasha lecture 29.5.23

  • Amos Kaminski (Weizmann) - The Rigidity Theorem extension of pseudo-isometries (based on Benedetti and Petronio’s book, pages 83–94). Recording

  • Itamar Vigdorovich (Weizmann) - Algebraic actions, Borel's density theorem, and applications. Recording

Midrasha lecture 22.5.23

  • Leonardo Lerer (Weizmann) - An introduction to strata of abelian differentials and their bi-algebraic geometry. Recording

  • Tom Meyerovitch (BGU) - Well-distribution of Polynomial maps on locally compact groups. Recording

Midrasha lecture 15.5.23

  • Arielle Leitner (Afeka) - Hyperbolic manifolds and the two-dimensional case (based on Benedetti and Petronio’s book, pages 45–61). Recording

  • Biao Ma (Technion) - On boundary representations of mapping class groups. Recording

Midrasha lecture 8.5.23

  • Guy Kapon (Weizmann) - Hyperbolic space models, isometries, geodesics, subspaces and curvature (based on Benedetti and Petronio’s book, pages 1–44). Recording

  • Andrei Alpeev (Weizmann) - Amenability is equivalent to the invariant random extension property. Recording

Midrasha lecture 17.4.23

  • Igor Spiridonov (Weizmann and the National Research University Higher School of Economics) - On the homology of the Torelli group. Recording

  • Uri Bader (Weizmann) - Algebras, their C-envelopes and the associated positivstellensatz. Recording

 

Fall semester

Midrasha lecture 16.1.23

  • Idan Pazi (Weizmann) - Analysis on compact groups and the Peter–Weyl theorem (based on Folland’s book, pages 144–160). Recording

  • Orr Shalit (Technion) - Dilation theory in action. Recording

Midrasha lecture 9.1.23

  • Yuval Grofine (Weizmann) - Analysis on compact groups and the Peter–Weyl theorem (based on Folland’s book, pages 135–144). Recording

  • Arie Levit (TAU) - Stationary random subgroups in negative curvature. Recording

Midrasha lecture 2.1.23

  • Nikolay Bogachev (Institute for Information Transmission Problems & Moscow Institute of Physics and Technology) - From geometry to arithmetic of hyperbolic orbifolds. Recording 1 Recording 2 (Shared screen)

  • Dani Weiss (McGill) - Nonpositive Towers in Bings Neighborhood. Recording

Midrasha lecture 26.12.22

  • Tobias Hartnick (Karlsruher Institut für Technologie) -Introduction to transverse point processes. Recording 1 Recording 2 (Shared screen)

Midrasha lecture 19.12.22

  • Peleg Bar Sever (WIS) - Closed ideals in L¹(G). Recording

  • Carlos De La Cruz Mengual (WIS) - Bounded cohomology and the isomorphism conjecture. Recording

Midrasha lecture 12.12.22

  • Guy Kapon (WIS) - The Pontryagin duality and the representation theory of locally compact abelian groups. Part 1 Part 2

  • Joshua Frisch (École Normale Supérieure) - The Liouville property for linear groups. Recording

Midrasha lecture 5.12.22

  • Amos Kaminski (WIS) - Fourier analysis on locally compact abelian groups. Recording

  • Ilan Hirshberg (BGU) - Dimension theory for discrete group actions and the nuclear dimension of their crossed products. Recording 1 recording 2 (shared screen)

Midrasha lecture 21.11.22

  • Yuval Salent (WIS) - Functions of positive type and the Gelfand–Raikov Theorem.  Recording

  • Or Landesberg (Yale) - Non-Rigidity of Horocycle Orbit Closures in Geometrically Infinite Surfaces. Recording

Midrasha lecture 14.11.22

  • Guy Salomon (WIS) - Introduction to harmonic analysis and unitary group representations. Recording

  • Alon Dogon (WIS) - Hyperlinearity versus flexible Hilbert Schmidt stability for property T groups. Recording

 

"Midrasha on Groups" lectures, 2021 - 2022

Prof. Uri Bader, Prof. Alex Lubotzky and Prof. Tsachik Gelander.

Spring Semester

Midrasha lecture, 09.05.22:

  • Tsachik Gelander (Weizmann Institute): Linear representations of the free group. Recording

  • Hanna Oppelmayer (BGU): Random walks in view of commensurated subgroups. Recording

Midrasha lecture, 25.04.22:

  • Tsachik Gelander (Weizmann Institute):  A series of lectures around the Weigold conjecture (Lecture 1). Recording

  • Tattwamasi Amrutan (BGU): Invariant Subalgebras of 'Singular' crossed products. Recording

Midrasha lecture, 11.04.22:

  • Alex Lubotzky (Weizmann Institute): The dynamics of Aut(Fn) actions on group presentations and representations. Recording

  • Roman Sauer (Karlsruhe Institute of Technology): Cohomology of arithmetic groups in degrees up to the rank Recording

 

Fall Semester

Midrasha lecture, 22.02.22:

  • Alon Dogon (Weizmann): Lück’s approximation theorem part 2 Finishing off by determinants.  Recording

  • Aviv Taller (Weizmann): Actions on median spaces and algebras and the Poisson boundary. Recording

Midrasha lecture, 15.02.22:

  • Alon Dogon (Weizmann): Lück’s approximation theorem part 1 motivation and statement Recording

  • Shaked Bader (Technion): CAT(0) polygonal complexes are 2-median Recording

Midrasha lecture, 03.01.22:

  • Gil Goffer (Weizmann): Uniformly recurrent subgroups Recording

  • Daniel Wise (McGill): A graph coloring problem and the virtual fibering of right-angled coxeter groups. Recording

Midrasha lecture, 27.12.21:

  • Oren Becker (Cambridge): Character varieties of random groups Recording

  • Amitay Kamber (Cambridge): Closed Orbits in Combinatorics Recording

Midrasha lecture, 13.12.21:

  • Andreas Wieser (HUJI): Equidistribution of rational subspaces of R^n Recording

  • Thomas Vidick (Caltech): Efficient stability for the Pauli (Weyl-Heisenberg) group Recording

Midrasha lecture, 06.12.21:

  • Carlos De la Cruz : l2-Betti numbers of groups, with computations Recording

  • Uri Bader : Locally compact subgroups of algebraic groups Recording

Midrasha lecture, 29.11.21:

  • Benjamin Bachner : l2-Betti numbers of spaces, with computations Recording

  • Nir Lazarovich : Volume vs. complexity of hyperbolic groups Recording

Midrasha lecture, 22.11.21:

  • Jonathan Zin : G-CW-complexes Recording

  • Eli Shamovich : Noncommutative convexity and group actions Recording

Midrasha lecture, 15.11.21:

  • Yeari Vigder : Von Neumann dimension Part 1 Part 2

  • Alon Dogon :  ​​​Failure of flexible HS-stability and Kirchberg’s Lifting Property for group C*-algebras Part 1 Part 2

Midrasha lecture, 08.11.21:

  • Michael Glasner : Background talk on von Neumann algebras Part 1 Part 2

  • Alon Dogon :  ​​​On uniform Hilbert Schmidt stability of groups Part 1 Part 2

Midrasha lecture, 01.11.21:

  • Aviv Taller: Crash course on cellular homology and group homology.  Part 2

  • Edgar Bering:  ​​​Topological models of abstract commensurators Part 1 Part 2

Midrasha lecture, 26.10.21:

  • Carlos Alberto De La Cruz Mengual: What are l2-invariants and why do we care? Recording

  • Itamar Vigdorovich:  ​​​Amenable invariant random subgroups Recording

 

"Midrasha on Groups" lectures, 2020 - 2021

Prof. Uri Bader and Prof. Tsachik Gelander.

Fall Semester

Midrasha lecture, 13.01.21:

  • Sheve Leibtag : Minimal topology og Aut(T).

  • Bruno Duchense:  ​​​A group with Property (T) acting on the circle.

Recording (of both lectures)

Midrasha lecture, 06.01.20:

  •  Raz Slutsky : On the Asymptotic Number of Generators of High-Rank Arithmetic Lattices.

  • Gil Goffer:  : Is invariable generation hereditary?

Recording (of both lectures)

Midrasha lecture, 30.12.20:

  • Itamar Vigodorovich: Furstenberg's proof for stiffness of actions on tori.

  • Ilya Ghektman:  Probabilistic and deterministic compactifications of groups.

Recording (of both lectures)

Midrasha lecture, 23.12.20:

  • Alexey Norkin: The nerve lemma.

  • Guy Salomon:  Amenability, proximality, and higher order syndeticity

Recording (of both lectures)

Midrasha lecture, 16.12.20:

  • Paul Volrath: Flat Strips and assorted Theorems.

  • Adam Dor-On : Operator algebras for subshifts and random walks

Recording (of both lectures)

Midrasha lecture, 09.12.20:

  • Anna's Rohova: Overview on the Morse theory.

  • Yair Hartman: Random walks on dense subgroups (continued).

Recording (of both lectures)

 

Midrasha lecture, 02.12.20:

  • Aviv's Taller: Median Algebras

 

  • Yair's Hartman: Random walks on dense subgroups.

Recording (of both lectures)

 

Midrasha lecture, 25.11.20: 

 

  • Guy Salomon: Operator theoretic methods in dynamics (3/3) Recording

  • Pierre-Emmanuel caprace: Hyperbolic groups, property (T) and finite simple quotients: a naturalist approach

Midrasha lecture, 18.11.20:

  • Guy Salomon: Operator theoretic methods in dynamics (2/3)

  • Martin Bobb: Codimension-1 Flats in Divisible Convex Sets 

  • Recording (of both lectures)

Midrasha lecture, 11.11.20:

Midrasha lecture, 04.11.20:

Midrasha lecture, 28.10.20:

  • Bader Gelander: Itroduction to Midrasha.  Video

 

Spring Semester 

Midrasha lecture, 22.07.20:

  • Elyasheev Leibtag: Algebraic Rings and Non-Linearity.

  • León's Carvajales: Growth of quadratic forms under Anosov subgroups.

  • Recording (of both lectures)

Midrasha lecture, 15.07.20:

  • Yaniv Shahar: Introduction to Exponential Growth of Groups.

  • Bakul Sathaye: Obstructions to Riemannian smoothings of locally CAT(0) manifolds.

  • Recording (of both lectures)

Midrasha lecture, 08.07.20:

  •  Paul Vollrath: Arithmetic lattices in simple Lie Groups.

  • Or Landesberg: Horospherically invariant measures and ends of hyperbolic 3-manifolds.  

    Recording (of both lectures)

Midrasha lecture, 01.07.20:

  • Bertrand Deroin: Non left-orderability of lattices in higher rank semi-simple Lie groups.

    Recording

Midrasha lecture, 24.06.20:

  • Steve Terttel: Intrinsic views of the Thurston Geometries. Recordings

Midrasha lecture, 17.06.20:

Midrasha lecture, 10.06.20:

  • Zohar Reizis : Decomposition Theorem in Hilbert spaces and vanishing of cohomology for groups acting on simplicial complexes.

  • Elia Fioravanti: Cubulations are determined by their length function. Lecture notes.

    Recording (of both lectures)

Midrasha lecture, 27.05.20:

  • Raz Slutsky: Growth in algebraic groups over finite fields.

  • Tali Pinsky: New Anosov flows from the modular surface.

    Recording (of both lectures)

Midrasha lecture, 20.05.20:

Midrasha lecture, 13.05.20:

  • Itamar Vigodorovich:Introduction to quantum ergodicity.

  • Maria Gerasimova: Isoperimetry, Littlewood functions, and Unitarisability of Groups.

    Recording (of both lectures)

Midrasha lecture, 06.05.20:

  • Tsachik Gelander: 3 proofs for the Kazhdan-Margulis Theorem. video
  • Yannick Krifka :The IRS compactification of moduli space. Talk slides

Midrasha lecture, 19.04.20:

  • Tsachik Gelander: 3 proofs for the Kazhdan-Margulis Theorem.
  • Arie Levitt: Quantitative weak uniform discreteness.
     video (both lectures)

Fall Semester

Midrasha lecture, 15.01.20:

  • Kevin Boucher: Introduction to weak amenability. 

Midrasha lecture, 08.01.20:

  • Aviv Taller: Quasi-Isometries!

Midrasha lecture, 01.01.20:

  • Claire Burrin: Discrete orbits in the plane and automorphic forms. Video

Midrasha lecture, 18.11.19:

  • Shamgar Gurevich: Harmonic analysis on GL(n) over finite fields.

Midrasha lecture, 11.11.19:

  • Carlos De la Cruz: Actions on the circle and bounded euler class.

Midrasha lecture, 04.12.19:

  • Carlos De la Cruz: Actions on the circle and bounded euler class.

Midrasha lecture, 27.11.19:

  • Yair Hartman: Z-ameanable actions.

Midrasha lecture, 20.11.19:

Midrasha lecture, 13.11.19:

  • Uri Bader: Property T and group rings.

Midrasha lecture, 06.11.19:

  • Nir Avni: Schroedinger Operators on Trees. Video

"Midrasha on Groups" lectures, 2018-2019.

Prof. Uri Bader and Prof. Tsachik Gelander.

Spring Semester

Midrasha lectures, 26.6.19:

  • Aviv Taller: Gromov-Hausdorff convergence, Gromov's compactness criterion and Tsachik's proof why the sphere can't be approximated by finite homogeneous metric spaces. Video

Midrasha lectures, 19.6.19:

  • Anton Hase: Fiber bundles connections and holonomies. Video

  • Arielle Leitner : Projective geometric structures and generalized cusps.

Midrasha lectures, 29.5.19:

  • Paul Vollrath: The model space M_k^n and isometries of hyperbolic spaces.Video

  • Uri Bader: What is a proper action on a non-proper quasi-tree. Video

  • Kuji Fujiwara: Group actions on quasi-trees. Video 

Midrasha lectures, 13.5.19:

  • Chen Meiri: On hyperbolic reflection groups and quadratic forms. Video 1  Video 2

  • Vikram Aithal: On spherical buildings.

Midrasha lectures, 1.5.19:

  • Raz Slutsky: Integral simplicial volume Video 

  • Uri Bader: Introduction to arithmetic groups Video 

Midrasha lectures, 24.4.19:

  • Ido Grayevsky: Combinatorial introduction to buildings Video 

  • Itamar Vigdorovich: Quantum homological codes  Video 

Fall Semester

Midrasha lectures, 13.2.19:

  • Raz Slutsky: Bounded cohomology - an introduction Video 

  • Omer Lavi: An example of a group with property (T) - the Steinberg group
     

Midrasha lectures, 30.1.19:

Midrasha lectures, 6.2.19:

  • Elyasheev Leibtag: Homomorphic images of algebraic groups. Video 

  • Gil GOffer: On uniform structures and completions of groups.

Midrasha lectures, 23.1.19:

  • Aviv Shalit: On bilinear forms.

  • Tsachik Gelander: exposition on the thick-thin decomoposition Part 1/1

  • Uri Bader: Mapping torus Part 1/1

Midrasha lectures, 16.1.19:

  • Kevin Boucher: Freeness inside of Gromov hyperbolic group.

  • Gil Goffer: Almost-Automorphisms of Trees

Midrasha lectures, 9.1.19:

  • Itai Glazer: Word maps and (probabilistic) Waring type problems (continued).
  • Eitan Amos: P-adic fields and their extensions.

Midrasha lectures, 2.1.19: (Action Now)

  • Yair Hartman: Which groups have bounded harmonic functions? Video

  • Nir Lazarovich: Flexible Stability of Surface Group Video

  • Barak Weiss: A crash course on Ratner's theorems Video

Midrasha lectures, 26.12.18:

  • Tsahik Gelander: survey on the Thin-Thick decomposition.
  • Uri Bader: Coarse spaces.

  • Itai Glazer: Word maps and (probabilistic) Waring type problems (continued).

Midrasha lectures, 19.12.18:

Midrasha lectures, 12.12.18:

  • Gil Goffer: Bass-Serre theory and discuss PSL_2(Z) and other tree lattices. Part 1 Part 2 Part 3

  • Tsachik Gelander: Thurston's thick-thin decomposition.

Midrasha lectures, 05.12.18:

  • Federico (continued) 

  • Anna: Oseledec Theorem and Lyapunov exponents.

  • Manuel (continued)

  • Daniel: The Fundamental group in Nonpositive Curvature

Midrasha lectures, 28.11.18:

  • Federico: An invitation to hyperbolic surfaces: the Dehn-Nielsen-Baer Theorem  Part 1 Part 2

  • Manuel: Counting primitive integer vectors using Eskin-Mcmullen  Part 1 Part 2

Midrasha lectures, 21.11.18:

  • Kyle: C* algerbas, vector bundles and the Serre-Swan theorem  lecture videos

  • Arielle: on Thurston geometries and more Part 1 Part 2

Midrasha lectures, 14.11.18:

  • Pierre-Emannuel Caprace: In a group every couple is irreducibly faithfull 

  • Itamar Vigdorovich: Constructions of aspherical manifolds, and asphericalization of polyhedra

Midrasha lectures, 7.11.18:

  • Itamar Vigdorovich: Constructions of aspherical manifolds, and asphericalization of polyhedra Part 1a Part 1b

 

ICM 2018

  • Asymptotic invariants of locally symmetric spaces –Talk by Tsachik Gelander.

 

"Midrasha on Groups" lectures, 2017-2018.

Spring semester 

 

Midrasha lectures, 4.7.18:

Midrasha lectures, 19.6.18:

  • Alex Furman: Multiplicative Ergodic Theorems and Lyapunov Exponents.

Midrasha lectures, 13.6.18:

  • Anish Gosh and Shreyasi Data discuss "Connections between dynamics and number theory". lecture videos (Shreyasi)

Midrasha lectures, 6.6.18:

Midrasha lectures, 30.5.18:

Midrasha lectures, 16.5.18:

  • Leonid Potyagalio: Martin and Floyd boundaries of finitely generated groups. lecture videos

  • Nadav Gropper: Property (T) -  Continued. 

Midrasha lectures, 9.5.18:

Midrasha lectures, 2.5.18:

Midrasha lectures, 25.4.18:

  • Yaniv Shahar: Lattices in locally compact groups.  part a part b

  • Itamar Vigdorovich: Codes and locally symmetric spaces. part a part b

Midrasha lectures, 11.4.18:

  • Itamar Vigdorovich: Locally symmetric spaces, Lie groups, and quantum codes. part a part b

  • Gili Mitki: Nielsen Theorem, graphic proof. part a part b

Midrasha lectures, 28.3.18:

  • Kyle Austin: Applications of Coarse Geometry and its Evolution to Dynamics. part a part b

  • Elyasheev Leibtag: An Introduction to Coarse Geometry and Asymptotic Dimension. Lecture notes

 

 

Fall Semester

Midrasha lectures, 31.1.18:

 

Midrasha lectures, 24.1.18:

 

Midrasha lectures, 17.1.18:

  • Ido Grayevsky: Universal subgroups of Aut(T)   part a  part b

  • Jonathan Bauch: A survey on Aut(F_n) 2

 

Midrasha lectures, 10.1.18:

  • Michael Magee: Integrals over unitary groups, maps on surfaces, and Euler characteristics    part a  part b

  • Jonathan Bauch: A survey on Aut(F_n) 1

 

Midrasha lectures, 3.1.18

  • Raz Slutsky: the Siegel transform and the lattice SL2(Z)

  • Elyasheev Leibtag: Uniform spaces   part a  part b

 

Midrasha lectures, 27.12.17

  • Tsachik Gelander: Automorphism groups on representation varieties   part a  part b

  • Gil Goffer: Groups acting freely on a tree   part a  part b

 

Midrasha lectures, 20.12.17

  • Yaniv Shahar: SL2(Z) and its action on the hyperbolic plane   part a  part b

  • Gil Goffer: Introduction to AutT   part a  part b

 

    Midrasha lectures, 13.12.17

    • Nir Avni: Width of words   part a  part b

    • Yaniv Shahar: SL2(R) and its action on the hyperbolic plane   part a  part b

     

    Midrasha lectures, 6.12.17

    • Anna Rohova: Hyperbolic plane geometry 2   part a  part b

    • Uri Bader: Positive definite functions and characters 2   part a  part b

     

    Midrasha lectures, 30.11.17

    • Anna Rohova: Hyperbolic plane geometry 1   part a  part b

    • Uri Bader: Positive definite functions and characters 1   part a  part b

     

    Midrasha lectures, 22.11.17

     

    Midrasha lectures, 15.11.17

     

    Midrasha lectures, 8.11.17

     

    Tsachik's Jazz concerts (recommended!!)