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The Elisha Netanyahu Memorial Lecture

High dimensional expanders and Ramanujan complexes

Professor Alex Lubotzky - Hebrew University of Jerusalem

April 1, 2015, at 17:00

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Faculty Activities
 Algebra Seminar - Darrell Haile
02/04/2015, Thursday, 13:30
Type Seminar Algebra Seminar On the Teichmuller map and a class of nonassociative algebras Darrell Haile Amado 814, Technion This work is joint with Yuval Ginosar. Let K/F be a finite Galois extension with Galois group G. The Teichmuller map is a function that associates to every central simple K-algebra B normal over F an element of $H^{3}(G,K^{\times})$. The value of the function is trivial precisely when the class of B is restricted from F. The classical definition of this map involves the use of a crossed-product algebra over B. This associativity of this algebra is also equivlaent to the class of B being restricted from F. The aim of this lecture is to elucidate the nature of the nonassociative algebras that arise when B is normal, but not restricted. It turns out that the resulting theory is remarkably similar to the theory of associiative algebras arising from the noninvertible cohomology of a Galois extension L/F such that L contains K and I want to explain that relationship. Yakov Karasik, yaakov@tx.technion.ac.il 1448 http://www.math.technion.ac.il/Site/events/EvntOffices/event.php?eid=tm1448
 Groups, dynamics and related topics - Oskar Hamlet
02/04/2015, Thursday, 14:45
Type Seminar Groups, dynamics and related topics Tight Maps and Homomorphisms II Oskar Hamlet Amada 814, Technion Abstract (s) : A homomorphism between Hermitian Lie groups is said to be tight if the norm of the bounded Kaehler class is preserved under the pullback. Parallell to tight homomorphisms is the notion of tight totally geodesic maps between the corresponding symmetric spaces. Tightness plays an important role in the study of maximal (with respect to the Toledo invariant) representations of surface groups in Hermitian Lie groups. In the first seminar I will give the basic definitions and introduce some of the tools used for studying tight maps/homomorphisms. In the second seminar I will present my work classifying tight maps. Parts of this work is joint with T. Okuda and M. B. Pozzetti. Dustin Mayeda, dmayeda@tx.technion.ac.il 1439 http://www.math.technion.ac.il/Site/events/EvntOffices/event.php?eid=tm1439
 Geometry and Topology seminar - Uri Bader (Technion)
02/04/2015, Thursday, 15:45
Type Seminar Geometry and Topology seminar Linearity vs. non-linearity of some automorphism groups of buildings Uri Bader (Technion) Amado 814, Technion An &quot;affine building&quot; is a geometric object attached to algebraic groups over local fields by a theory developed by Bruhat and Tits in way parallel to Cartan's more familiar theory of symmetric spaces. Nevertheless, there is a striking difference: in rank 1 and 2 one can find buildings which are not attached to any algebraic group (this never happens for symmetric spaces, nor for higher-rank affine buildings). One then asks: for such &quot;exotic&quot; buildings, could the automorphism group be linear at all? In a recent joint work with Caprace and Lecureux we give a negative answer to this question. Our method involves a combination of geometry, representation theory and ergodic theory. Tobias Hartnick, hartnick@tx.technion.ac.il 1441 http://www.math.technion.ac.il/Site/events/EvntOffices/event.php?eid=tm1441
 PDE and Applied Mathematics Seminar - Arik Yochelis (BGU)
14/04/2015, Tuesday, 14:30
Type Seminar PDE and Applied Mathematics Seminar Origin of finite pulse trains in reaction-diffusion PDEs: Homoclinic snaking in excitable media Arik Yochelis (BGU) Amado 814, Technion Spatially localized and stationary states have recently brought to the spotlight of mathematical analysis of nonlinear PDEs via analysis of models exhibiting free energy and/or conservation. However, many chemical and biological systems exhibit rather localized traveling pulses, such as action potentials in axons and cardiac muscles. We identify and describe a qualitative novel property of excitable media that enables us to generate a sequence of traveling pulses of any desired length, using a one-time initial stimulus. The existence of these states is related here to the presence of homoclinic snaking in the vicinity of a subcritical, finite wavenumber Hopf bifurcation. The pulses are organized in a slanted snaking structure resulting from the presence of a heteroclinic cycle between small and large amplitude traveling waves. Connections of this type require a multivalued dispersion relation. This dispersion relation is computed numerically and used to interpret the profile of the pulse group. The different spatially localized pulse trains can be accessed by appropriately customised initial stimuli thereby blurring the traditional distinction between oscillatory and excitable systems. The results reveal a new class of phenomena relevant to spatiotemporal dynamics of excitable media, particularly in chemical and biological systems with multiple activators and inhibitors. Ram Band, ramband@tx.technion.ac.il 51 http://www.math.technion.ac.il/Site/events/EvntOffices/event.php?eid=eo51
 Algebra Seminar - Efrat Bank
16/04/2015, Thursday, 13:30
Type Seminar Algebra Seminar Prime polynomial values of linear functions in short intervals Efrat Bank Amado 814, Technion In this talk I will present a function field analogue of a conjecture in number theory. This conjecture is a combination of several famous conjectures, including the Hardy-Littlewood prime tuple conjecture, conjectures on the number of primes in arithmetic progressions and in short intervals, and the Goldbach conjecture. I prove an asymptotic formula for the number of simultaneous prime values of n linear functions, in the limit of a large finite field. A key role is played by the computation of some Galois groups. Yakov Karasik, yaakov@tx.technion.ac.il 1432 http://www.math.technion.ac.il/Site/events/EvntOffices/event.php?eid=tm1432
Center for Mathematical Sciences Activities
 CMS Special Lecture Series - Prof. John Hinch
27/04/2015, Monday, 15:30 - 30/04/2015, Thursday, 15:30
Type Lecture series CMS CMS Special Lecture Series Prof. John Hinch Monday 27.4- Segoh 1, Tuesday 28.4- room 814, Thursday 30.4- room 231, Technion Center for Mathematical Sciences Supported by the Mallat Family Fund for Research in Mathematics Invites you to a SPECIAL LECTURE SERIES Professor John Hinch Department of Applied Mathematics and Theoretical Physics  University of Cambridge    Lecture I: Explaining the behavior of elastic liquids Monday, 27 April, 2015 at 15:30, Segoh, Segoh 1. Lecture II: Viscous `drops' falling on a coated vertical fibre (quite technical and mathematical) Tuesday, 28 April, 2015 at 15:30, Amado, Room 814. Lecture III: Fluctuations in the sedimentation of particles in a suspension (review including resolution of long standing paradox) Thursday 30 April, 2015 at 15:30, Amado, Auditorium 231. For further administrative information please contact: Shiri Kaplan- Shabat, CMS Coordinator Phone: +972-(0)4-8294276\8 Fax: +972-(0)4-8293388 E-mail: cms@math.technion.ac.il Prof. John Hinch cms@math.technion.ac.il 32 http://www.math.technion.ac.il/Site/events/EvntOffices/event.php?eid=eo32
18/05/2015, Monday, 09:00 - 21/05/2015, Thursday, 16:00
Type Conference CMS Conference in honor of Lin's 80th Birthday T.B.A, Technion Center for Mathematical Sciences Conference on Algebraic Geometry, Braids, Analysis Technion - Israel Institute of Technology, Haifa, Israel May 18 - May 21, 2015 The conference is held on the occasion of Professor Vladimir Lin's 80th birthday Registration is now open until April 1st.   The aim of this conference is to bring together researchers working on algebraic geometry, braids, and analysis, and to discuss some of the recent developments and to identify important problems and new research directions.   Participants include: M. Agranovsky         P. Kuchment                  A. Pinkus T. Bandman              A. Libgober                   P. Russell G. Belitskii                 V. Lin                            I. Scherbak V. Bergelson              M. Lyubich                   V. Tkachenko A. Brudnyi                  Y. Lyubich                    V. Vassiliev  A. Eremenko              L. Makar-Limanov         B. Wajnryb          S. Gindikin                  K. Masuda                    Y. Zarhin   V. Gurarii                    V. Milman                     M. Zaidenberg  S. Kaliman                  M. Miyanishi                V. Zinde-Walsh   A. Khovanskii               A. Olevskii                   N. Zobin M. Koras                     S. Orevkov                        The conference is supported by The Center for Mathematical Sciences at the Technion and The  Gelbart Institute for Mathematical Sciences, Bar-Ilan University   Scientific Committee: Joan Birman, Mikhail Sodin, Evgeniĭ Gorin Organization Committee: Yehuda Pinchover, Michail Zhitomirskii   For further information please contact: Shiri Kaplan-Shabat (Conference Coordinator), E-mail cms@math.technion.ac.il ; Phone: +972-(0)4-8294278 Conference Web page: http://www.math.technion.ac.il/cms/decade_2011-2020/year_2014-2015/Lin/ List of Participants , Poster , Transportation cms@math.technion.ac.il 33 http://www.math.technion.ac.il/Site/events/EvntOffices/event.php?eid=eo33
17/06/2015, Wednesday, 09:00 - 24/06/2015, Wednesday, 16:00
Type Workshop CMS Generalizations of Symmetric Spaces Nachsholim Resort, Technion ERC                CMS Workshop on Generalizations of Symmetric Spaces 17th-24th June, 2015 Registration is now open Important Note: When booking your flight, please take into consideration that the conference shuttle leaves on June 17th at 10 am from Binyamina railway station, which is one hour by train from Ben Gurion airport. We thus recommend that you arrive either in the early morning of the 17th, or at the 16th. In the latter case we can help you find accommodation in Tel Aviv or Haifa for the night. The  following mini-courses will be given: Michel Brion (Institute Fourier) "Spherical Varieties" Kai-Uwe Bux (Universität Bielefeld) "Finiteness Properties of Arithmetic Groups" Dima Gourevitch (Weizmann Institute) "Multiplicity One Spaces" Bertrand Rémy (École Polytechnique) "Compactifications of Buildings"   Additional research talks will be given by the participants Organizers: Tobias Hartnick (Technion), Aloysius Helminck (NC State University), Ralf Köhl (JLU Gießen), Amos Nevo (Technion) For further administrative information please contact: Shiri Kaplan- Shabat, Workshop Coordinator Phone: +972-(0)4-8294276\8 Fax: +972-(0)4-8293388 E-mail: cms@math.technion.ac.il Poster cms@math.technion.ac.il 34 http://www.math.technion.ac.il/Site/events/EvntOffices/event.php?eid=eo34