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DTSTART:20211031T020000
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BEGIN:VEVENT
UID:calendar.3059966.field_date.0@mathematics.huji.ac.il
DTSTAMP:20220124T002219Z
CREATED:20211014T190024Z
DESCRIPTION:Date: \n\nThu\, 14/10/202111:00-13:00\nRepeats every week   eve
 ry Thursday 52 times   \n\n\nSee also: Kazhdan Sunday Seminars\, Events & 
 Seminars\, Seminars\n\n\n\n\n\n	NOTE UNUSUAL DAYLink: Topics in Model Theor
 y (Teams) 0.1. Provisional syllabus. This course is intended to cover thre
 e main results.They neighbour a large number of existing theorems and conc
 epts that there isno room to detail here\, and I will try to learn and exp
 lain some connections. See[1] and [2]\, and references there for adjacent 
 material. The proof of (3) dependslogically on (2)\, and (2) on (1)\; but 
 we may cover them in reverse order.1) The Hausdorff core of a theory.This 
 is a construction of a compact topological structure J canonically associa
 tedwith a given theory T\, along with a compact automorphism group G actin
 gon it. One view way to view G is as the group of self-interpretations of 
 a canonicalminimal expansion of the theory enjoying a structural Ramsey pr
 operty. Thusfor instance the proof of Ramsey’s original theorem requires t
 he use of a linearordering . The core and its automorphism group G become 
 locally compact if T is presented locally\; this locally compact group is 
 the starting point of the analysis of approximate subgroups in (2).2) Appr
 oximate subgroups.An approximate subgroup of a group G is a symmetric subs
 et X G\, suchthat the product set XX is commensurable to X\, i.e. is conta
 ined in a finiteunion of translates of X. Homomorphisms from f from a subg
 roup H of G into a Lie group L provide one source of approximate subgroups
 \; namely f^{-1}(U) where U is a compactneighborhood of the identity in L.
  Here L can be taken to be connected with nocompact normal subgroups\, and
  is then uniquely determined by the correspondingcommensurability class of
  approximate subgroups.Quasimorphisms g : H\to R also give rise\, by pullb
 ack of a bounded set\, toapproximate subgroups. These only arise for non-a
 menable G.Theorem 5.16 (or 5.19) in [1] shows that an approximate subgroup
  of any groupdecomposes into the above two special classes\, belonging to 
 Lie theory in the firstcase and bounded cohomology in the second.3) Approx
 imate lattices.An approximate subgroup X of a 2nd countable locally compac
 t group G iscalled an approximate lattice if it is discrete (and closed)\,
  and has finite covolumein the sense that there exists a Borel subset B of
  finite volume in G\, with XB = G.Assume G is an algebraic group over a lo
 cal field. The classical adelic construtionof arithmetic lattices in G ada
 pts to giving additional approximate lattices.The simplest example is the 
 approximate lattice {a/p^n\in Z[1/p] : |a|\leq  p^n} in(Q_p\; +)\, analogo
 us to the lattice Z in R\; both can be described as the set of  rationals 
 in a completion of Q\, whose norm in every other completion is bounded by 
 1. Theorem 8.4 of [1] shows that when G is semisimple\, this arithmetic co
 nstruction is the only additional source of approximate lattices. For inst
 ance any number field contained in R gives rise to an approximate lattice 
 in SL_2(R)\, and all approximate lattices of SL_2(R) are either commensura
 ble to one of these orto a lattice.References[1] arXiv:2011.12009[2] arXiv
 :1911.01129---------------------------------------------------------------
 -----------------------------------------------------------------Dear all\
 ,Now the text\, handwritten notes and video are all available here\, and w
 ill be updated:http://people.maths.ox.ac.uk/hrushovski/autumn2021.htmlThe 
 video at the moment is only of lecture 2\, thanks to Arturo\, but I think 
 this will be updated soon too.\n\n\nThu\, 14/10/202111:00-13:00\nRepeats e
 very week   every Thursday 52 times
DTSTART;TZID=Asia/Jerusalem:20211014T110000
DTEND;TZID=Asia/Jerusalem:20211014T130000
LAST-MODIFIED:20220118T120010Z
RRULE:FREQ=WEEKLY;COUNT=52;INTERVAL=1;BYDAY=TH;WKST=SU
SUMMARY:Kazhdan seminar: Ehud Hrushovski and Itay Kaplan - Topics in Model 
 Theory
URL;TYPE=URI:https://mathematics.huji.ac.il/event/kazhdan-seminar-ehud-hrus
 hovski-and-itay-kaplan-topics-model-theory
END:VEVENT
BEGIN:VEVENT
UID:calendar.3075447.field_date.0@mathematics.huji.ac.il
DTSTAMP:20220124T002219Z
CREATED:20220123T200031Z
DESCRIPTION:Date: \n\nThu\, 27/01/202211:00-12:00\n\n\nSee also: Amitsur Al
 gebra\, Seminars\, Events & Seminars\n\nLocation: \n\nZOOM\, https://huji.
 zoom.us/j/82813766376?pwd=VFl2a3YrVmthMUtFd2d2TE9Gd3pRQT09\n\n\nSpeaker: M
 ichael Chapman (HUJI)Title: Cutoff: new results and new methods.Abstract: 
  In recent years\, random walks on simplicial complexes proved extremely u
 seful. They were used\, for example\, to uniformly sample matroid bases\, 
 and to define high dimensional analogues of expansion. Meanwhile\, the cut
 off phenomenon for random walks received lots of attention as well. A rand
 om walk exhibits the cutoff phenomenon if the transition from being far fr
 om mixed to being very mixed happens (relatively) abruptly. In this talk w
 e plan to: Survey cutoff results and proof methods for graphs and for quot
 ients of Bruhat-Tits buildings.Discuss generalizations of a recent entropi
 c approach due to Ozawa. Apply these generalizations to Ramanujan complexe
 s that were not known previously to exhibit cutoff. Deduce cutoff results 
 on Cayley graphs arising from high dimensional theory.This talk is based o
 n a joint work with Ori Parzanchevski and Yuval Peled.ZOOM details:Linkhtt
 ps://huji.zoom.us/j/82813766376?pwd=VFl2a3YrVmthMUtFd2d2TE9Gd3pRQT09Meetin
 g ID: 828 1376 6376Passcode: 649336\n\nAdd to CalendarOutlook\nGoogle
DTSTART;TZID=Asia/Jerusalem:20220127T110000
DTEND;TZID=Asia/Jerusalem:20220127T120000
LAST-MODIFIED:20220123T200031Z
SUMMARY:Amitsur Seminar: Michael Chapman (HUJI)
URL;TYPE=URI:https://mathematics.huji.ac.il/event/amitsur-seminar-michael-c
 hapman-huji
END:VEVENT
BEGIN:VEVENT
UID:calendar.3075284.field_date.0@mathematics.huji.ac.il
DTSTAMP:20220124T002219Z
CREATED:20220121T190009Z
DESCRIPTION:Date: \n\nThu\, 03/03/202216:00-17:15\n\n\nSee also: Seminars\,
  Events & Seminars\, Basic Notions\n\nLocation: \n\nZoom\n\n\n Abstract:\n
  I will describe joint work with Constantin Teleman\, in which we cast top
 ological eyes on a well-studied system in condensed matter physics.  In pa
 rticular\, we use the symmetry in a strong  form and apply the technology 
 of extended topological field theory.  We obtain a proof of duality\, cons
 truct a new dual theory for models based on a nonabelian group\, and make 
 dynamical predictions.  The lecture will not assume any physics background
 .\n\nAdd to CalendarOutlook\nGoogle
DTSTART;TZID=Asia/Jerusalem:20220303T160000
DTEND;TZID=Asia/Jerusalem:20220303T171500
LAST-MODIFIED:20220121T190009Z
SUMMARY:Basic Notions: Dan Freed (U of Texas) - The two-dimensional Ising m
 odel revisited
URL;TYPE=URI:https://mathematics.huji.ac.il/event/basic-notions-dan-freed-u
 -texas-two-dimensional-ising-model-revisited
END:VEVENT
BEGIN:VEVENT
UID:calendar.3070449.field_date.0@mathematics.huji.ac.il
DTSTAMP:20220124T002219Z
CREATED:20211229T200022Z
DESCRIPTION:Date: \n\nThu\, 10/03/202216:00-17:15\n\n\nSee also: Seminars\,
  Events & Seminars\, Basic Notions\n\nLocation: \n\nRoss 70\n\nAdd to Cale
 ndarOutlook\nGoogle
DTSTART;TZID=Asia/Jerusalem:20220310T160000
DTEND;TZID=Asia/Jerusalem:20220310T171500
LAST-MODIFIED:20211229T200022Z
SUMMARY:Basic Notions: Dorit Aharonov (HUJI)
URL;TYPE=URI:https://mathematics.huji.ac.il/event/basic-notions-dorit-aharo
 nov-huji-0
END:VEVENT
BEGIN:VEVENT
UID:calendar.3075270.field_date.0@mathematics.huji.ac.il
DTSTAMP:20220124T002219Z
CREATED:20220121T060001Z
DESCRIPTION:Date: \n\nTue\, 22/03/202214:00-15:00\n\n\nSee also: Dynamical 
 & Probability\, Events & Seminars\, Seminars\n\nAdd to CalendarOutlook\nGo
 ogle
DTSTART;TZID=Asia/Jerusalem:20220322T140000
DTEND;TZID=Asia/Jerusalem:20220322T150000
LAST-MODIFIED:20220121T060001Z
SUMMARY:Andreas Wieser (HUJI)
URL;TYPE=URI:https://mathematics.huji.ac.il/event/andreas-wieser-huji
END:VEVENT
BEGIN:VEVENT
UID:calendar.3070448.field_date.0@mathematics.huji.ac.il
DTSTAMP:20220124T002219Z
CREATED:20211229T200022Z
DESCRIPTION:Date: \n\nThu\, 24/03/202216:00-17:15\n\n\nSee also: Seminars\,
  Events & Seminars\, Basic Notions\n\nLocation: \n\nRoss 70\n\nAdd to Cale
 ndarOutlook\nGoogle
DTSTART;TZID=Asia/Jerusalem:20220324T160000
DTEND;TZID=Asia/Jerusalem:20220324T171500
LAST-MODIFIED:20211229T200022Z
SUMMARY:Basic Notions: Dorit Aharonov (HUJI)
URL;TYPE=URI:https://mathematics.huji.ac.il/event/basic-notions-dorit-aharo
 nov-huji
END:VEVENT
BEGIN:VEVENT
UID:calendar.3072044.field_date.0@mathematics.huji.ac.il
DTSTAMP:20220124T002219Z
CREATED:20220103T050913Z
DESCRIPTION:Date: \n\nTue\, 29/03/202214:00-15:00\n\n\nSee also: Dynamical 
 & Probability\, Events & Seminars\, Seminars\n\nAdd to CalendarOutlook\nGo
 ogle
DTSTART;TZID=Asia/Jerusalem:20220329T140000
DTEND;TZID=Asia/Jerusalem:20220329T150000
LAST-MODIFIED:20220121T060001Z
SUMMARY:No dynamics seminar (Zabrotsky lecture)
URL;TYPE=URI:https://mathematics.huji.ac.il/event/shrey-sanadhya-bgu-0
END:VEVENT
BEGIN:VEVENT
UID:calendar.3075269.field_date.0@mathematics.huji.ac.il
DTSTAMP:20220124T002219Z
CREATED:20220121T060001Z
DESCRIPTION:Date: \n\nTue\, 12/04/202214:00-15:00\n\n\nSee also: Dynamical 
 & Probability\, Events & Seminars\, Seminars\n\nAdd to CalendarOutlook\nGo
 ogle
DTSTART;TZID=Asia/Jerusalem:20220412T140000
DTEND;TZID=Asia/Jerusalem:20220412T150000
LAST-MODIFIED:20220121T060001Z
SUMMARY:Dynamics seminar: Shrey Sandhaya (BGU)
URL;TYPE=URI:https://mathematics.huji.ac.il/event/dynamics-seminar-shrey-sa
 ndhaya-bgu
END:VEVENT
END:VCALENDAR