Seminars and Workshops
Past seminars and workshops
Hot Topics: MIP* = RE and the Connes’ Embedding Problem
Amitsur Algebra Seminar
2019-2022 -- The Hebrew University
I organized the seminar under the instruction of Professors Lubotzky, Mann and Shalev. Link to the calendar.
Graduate students seminar
2018-2022 -- The Hebrew University
This seminar is currently organized by Shai Evra, Ziv Maayan and George Peterzil.
Past organizers: Amichai Lampert and I organized the seminar under the supervision of Cy Maor. Other past organizers: Or Landsberg, Yatir Halevi.
Topics in group theory students seminar
The Hebrew University
Alon Dogon and I organized a graduate student's seminar on topics in group theory.
Other past organizers: Oren Becker, Bharatram Rangarajan, Amitay Kamber.
2022 Fall semester
The topic of this semester is algebraic and arithmetic groups. We work in parallel to the IAS seminar organized by Alex Lubotzky and Peter Sarnak.
2021 Spring semester
Profinite rigidity. Notes. (Amir Behar)
Commuting probabilities of finite groups. Notes 1,2 (Tzoor Plotnikov)
Buildings in the context of symmetric spaces. (Ido Grayevsky)
Introduction to character theory. (Itamar Vigdorovich)
Classical rigidity theorems via characters on groups. Notes (Alon Dogon)
Topological full groups and local embeddings into finite groups. (Danielle Dona)
The seminar takes place on Wednesdays 16:00 to 17:30 in room 110 Manchester building
2021 Fall semester
Invariant Random Subgroups: Stuck-Zimmer Theorem Notes. (Amitay Kamber)
Simple groups of dynamical origin. Notes. Additional notes (Alon Dogon)
Bounded cohomology and simplicial volume. Notes. (Bharatram Rangarajan)
Amenable groups and actions: Characterizations, Connes-Feldman-Weiss. Notes. (Hagai Levner)
Crash course in algebraic topology. (Danil Akhtiamov)
Rates of growth in hyperbolic groups. Notes1. Notes2. Notes3. Fujiwara--Sela. (MIchael Chapman)
Introduction to K theory. Notes (another link). (Alon Dogon)
Vertex expansion and spectral expansion. Notes1. Notes2. (Amitay Kamber)
The seminar takes place on Tuesdays, 14:00 to 15:45 on ZOOM.
2019 Spring semester
Kazhdan's Property (T): characterizations, proofs for various groups and applications -- [Notes] (Oren Becker)
Ozawa's proof method of Property (T) for Aut(Fn). (Hagai Levner)
Garland's method in the combinatorial setting -- [Notes] (Amitay Kamber)
Broder-Shamir's theorem on the expansion of random graphs. (Michael Chapman)
The seminar took place on Sundays, 17:00 to 20:00, at the Junior Staff Room, Ross Building (near the kitchen).
Possible future topics
Introduction to algebraic and arithmetic groups.
Group Actions on Trees and Bass-Serre theory.
The profinite topology on abstract groups with interesting examples.
Hyperbolic groups.
Growth in groups: subgroup growth, Dehn function, Gromov's polynomial growth theorem.
The talks are meant to be highly accessible to all graduate students.
2020-2021 fall and spring semesters -- The Hebrew university
Nati Linial, Alex Lubotzky and I organized a seminar dedicated to the recent refutation of Connes' embedding problem.
Relevant links
Fall semester 2020-2021 content:
ZOOM links, slides and video recordings:
Lec1, October 18, 2020, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec2, October 25, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec3, November 1, 16:00-18:00 Jerusalem time. Slides. YouTube. This lecture is dedicated to my grandfather Zvi Luz who passed away on Nov 1 2020.
Lec4, November 8, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec5, November 15, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec6, November 22, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec7, November 29, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec8, December 6, 16:00-18:00 Jerusalem time. Slides. Slides annotated. YouTube. (Alon Dogon)
Lec9, December 20, 16:00-18:00 Jerusalem time. Slides. YouTube. (Guy Kindler)
Lec10, December 27, 16:00-18:00 Jerusalem time. Slides. YouTube. (Guy Kindler)
Lec11, January 3, 2021, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec12, January 10, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec13, January 17, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec14, April 11, 16:00-18:00 Jerusalem time. Slides 1 , 2. YouTube. (Alon Dogon & Danil Akhtiamov)
Lec15, April 18, 16:00-18:00 Jerusalem time. Slides 1, 2. YouTube. (Alon Dogon)
Lec16, April 25, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec22, June 20, 16:00-18:00 Jerusalem time. Slides. YouTube.
Lec23, June 27, 16:00-18:00 Jerusalem time. Slides. YouTube.
Papers we follow
MIP*=RE, Quantum soundness of the classical low individual degree test, NEEXP in MIP*, A multi-prover interactive proof for NEXP sound against entangled provers, Interactions with Quantum Devices.
Talks and links we like
This talk by Anand Natarajan
This seminar on Operator Algebras and Quantum Information
The talks about MIP*=RE as well as the self testing talk in Quantum Protocols: Testing & Quantum PCPs
These talks by Henry Yuen: 1,2,3
Undergraduate summer workshop at HUJI
Aug 22 - Sep 3, 2021
TAs
Links
Expander graphs survey by Hoory, Linial & Wigderson
Algebraic coding theory course on YouTube by Wootters
A survey on Expanders and Kazhdan property (T) by Giles Gardam
Small diameter Cayley graphs for finite simple groups by Babai, Kantor and Lubotzky
Expansion in simple groups by Breuillard and Lubotzky
A short proof of Jacobi's 4 squares formula by E. Andrews, Shalosh B. Ekhad (funny) and D. Zeilberger
Super Strong Approximation in Groups
2018-2019 Spring semester -- The Hebrew University
Dates: 17-21.2.2019 Tomer Schlank, Oren Becker and I organized a workshop whose goal was to study Super Strong Approximation in Groups:
The goal of the workshop was to study the proof of super-strong approximation via the Bourgain-Gamburd expansion machine, the classification of approximate subgroups of semisimple algebraic groups over finite fields, and random matrix products. We followed the paper Approximate subgroups and super-strong approximation by Emmanuel Breuillard. The talks were given by graduate students and post-docs.
Stallings' Foldings and their applications
2017-2018 spring semester -- The Hebrew University
Noam Kolodner and I, with help from Ori Parzanchevski, organised a seminar centred around Stallings' foldings and their applications. The goal of the seminar was to study the paper Measure Preserving Words are Primitive by Puder and Parzanchevski. Lecture notes (Partially Hebrew): [1] [2] [3] [4] [5] [6] [7] [8]
July 2019 update: Recently Ofir David uploaded to arXiv a paper related to what we have done in the seminar and specifically to the talk he gave (link to the paper on arXiv)
Announcement June 2021: There is a second round of this amazing workshop. YouTube. Website. This year the topics are
Isoperimetry.
Cubulated groups and virtual specialness.
The Poisson boundary and bounded harmonic functions on groups.
Anosov representations of hyperbolic groups.
Acylindrically and relatively hyperbolic groups.
Artin groups
July 20-31, 2020
I mentored the "Expander Graphs" exercise session.
Videos from the workshop are available in the following link: GGTWB YouTube. If you want to learn either of the following subjects, the videos are highly recommended:
Expander graphs.
Bass-Serre theory.
The mapping class group.
Automorphisms of free groups and outer space.
Incoherence.
Hierarchically hyperbolic groups.