Eventss

2020 Mar 19

Colloquium: CANCELLED

2:30pm to 3:30pm

Location: 

Manchester Building (Hall 2), Hebrew University Jerusalem

Abstract: A spanning tree of a graph G is a subgraph with the same vertex set which is a tree. In 1981, McKay proved an asymptotic result regarding the number of spanning trees in random k-regular graphs. In this talk we will discuss an analogous result for certain random simplicial complexes (All terms will be explained in the talk).
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The talk is based on a joint work with Lior Tenenbaum.
2019 Oct 27

Kazhdan Sunday seminar: Elon Lindenstrauss "Arithmetic applications of diagonal flows"

Repeats every week every Sunday until Sat Feb 01 2020 except Sun Oct 27 2019.
11:00am to 1:00pm

11:00am to 1:00pm
11:00am to 1:00pm
11:00am to 1:00pm
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11:00am to 1:00pm
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11:00am to 1:00pm
11:00am to 1:00pm
11:00am to 1:00pm

Location: 

Ross 70
Elon Lindenstrauss "Arithmetic applications of diagonal flows"
I will give an introduction to the dynamics of higher rank diagonal flows on homogeneous spaces,
including both the rigidity theorems of such flows and their applications to orbits of arithmetic interest,
in particular CM points and integer points on spheres.
I hope to cover parts of the following papers:
Einsiedler, Manfred ; Lindenstrauss, Elon ; Michel, Philippe ; Venkatesh, Akshay . The distribution of closed geodesics
2019 Oct 27

Kazhdan Sunday seminar: "Computation, quantumness, symplectic geometry, and information" (Gil Kalai, Leonid Polterovich, with participation of Dorit Aharonov and Guy Kindler)

Repeats every week every Sunday until Sat Feb 01 2020 except Sun Dec 29 2019.
2:00pm to 4:00pm

2:00pm to 4:00pm
2:00pm to 4:00pm
2:00pm to 4:00pm
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2:00pm to 4:00pm
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2:00pm to 4:00pm
2:00pm to 4:00pm
2:00pm to 4:00pm
2:00pm to 4:00pm
2:00pm to 4:00pm

Location: 

Ross 70

Tentative syllabus
1. Mathematical models of classical and quantum mechanics.
2. Correspondence principle and quantization.
3. Classical and quantum computation: gates, circuits, algorithms
(Shor, Grover). Solovay-Kitaev. Some ideas of cryptography
4. Quantum noise and measurement, and rigidity of the Poisson bracket.
5. Noisy classical and quantum computing and error correction, threshold theorem- quantum fault tolerance (small noise is good for quantum computation). Kitaev's surface code.
2019 Oct 27

Kazhdan Sunday seminar: Tomer Schlank "Prismatic cohomology" (after Bhatt and Scholze)

Repeats every week every Sunday until Sat Feb 01 2020 except Sun Oct 27 2019.
4:00pm to 6:00pm

4:00pm to 6:00pm
4:00pm to 6:00pm
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4:00pm to 6:00pm
4:00pm to 6:00pm
4:00pm to 6:00pm
4:00pm to 6:00pm
4:00pm to 6:00pm

Location: 

Ross 70
Tomer Schlank "Prismatic cohomology" (after Bhatt and Scholze)
Abstract: We shall discuss (Weil) cohomology theories for algebraic varieties.
When working with schemes over p-complete rings and taking cohomologies with p-complete coefficients one gets a plurality of such cohomology theories (e'tale, De-Rahm, Crystalline, etc.. ). The comparison between these different cohomology theories is a subtle subject known as "p-adic hodge theory" .
2019 Dec 18

Analysis Seminar: Moshe Goldberg (Technion) "Extending the Spectral Radius to Finite-Dimensional Power-Associative Algebras"

12:00pm to 1:00pm

Location: 

Ross 70

Title: Extending the Spectral Radius to Finite-Dimensional Power-Associative Algebras
Abstract: The purpose of this talk is to introduce a new concept, the \textit{radius} of elements in arbitrary finite-dimensional power-associative algebras over the field of real or complex numbers. It is an extension of the well known notion of the spectral radius.
As examples, we shall discuss this new radius in the setting of matrix algebras, where it indeed reduces to the spectral radius, and then in the Cayley-Dickson algebras, where it is something quite different.
2019 Oct 31

Colloquium: Leonid Polterovich (TAU) - Quantum footprints of symplectic rigidity

2:30pm to 3:30pm

Location: 

Manchester Building (Hall 2), Hebrew University Jerusalem
Title: Quantum footprints of symplectic rigidity
Abstract: I'll discuss an interaction between symplectic topology, a rapidly developing mathematical area originated as a geometric language for problems of classical mechanics, and quantum mechanics. On one hand, ideas from quantum mechanics give rise to new structures on the symplectic side, and quantum mechanical insights lead to useful symplectic predictions. On the other hand, some phenomena discovered within symplectic topology admit a translation into the language of quantum mechanics.
2019 Dec 12

Colloquium: Menachem Lazar (Bar Ilan) - Spatial point sets, level set geometry, and Voronoi topology structure analysis

2:30pm to 3:30pm

Location: 

Manchester Building (Hall 2), Hebrew University Jerusalem
Physical systems are regularly studied as spatial point sets, and so understanding the structure in such sets is a very natural problem. However, aside from several special cases, describing the manner in which a set of points can be arranged in space has been historically challenging. In the first part of this talk, I will show how consideration of the configuration space of local arrangements of neighbors, and a few simple results in metric geometry, can shed light on essential challenges of this problem, and in the classification of data more generally.
2019 Nov 07

Colloquium: Boaz Klartag (Weizmann) - Needle decomposition and Ricci curvature

2:30pm to 3:30pm

Location: 

Manchester Building (Hall 2), Hebrew University Jerusalem
Title: Needle decomposition and Ricci curvature
Abstract: Needle decomposition is a technique in convex geometry,
which enables one to prove isoperimetric and spectral gap
inequalities, by reducing an n-dimensional problem to a 1-dimensional
one. This technique was promoted by Payne-Weinberger, Gromov-Milman
and Kannan-Lovasz-Simonovits. In this lecture we will explain what
needles are, what they are good for, and why the technique works under
lower bounds on the Ricci curvature.
2019 Dec 24

Zabrodsky Lecture 3: The symplectic topologist as a homotopy theorist

Lecturer: 

Paul Seidel (MIT)
1:00pm to 2:00pm

Location: 

Ross Building, Room 70

Modern symplectic topology deals with objects of symplectic geometry indirectly, by associating to them auxiliary moduli spaces. This complicates its relation with homotopy theory. I will explain the overall framework that describes this relation (going back to Cohen, Jones and Segal), and some of the directions that are under investigation.

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