2015 Dec 03

Amitsur Algebra: Boris Plotkin (Hebrew U)

12:00pm to 1:15pm

Location:

Manchester Building (room 209), Jerusalem, Israel
Title: Algebraic Geometry in an arbitrary variety of algebras and Algebraic Logic Abstract: I will speak about a system of notions which lead to interesting new problems for groups and algebras as well as to reinterpretation of some old ones.
2015 Dec 24

Amitsur Algebra: Michael Larsen (Indiana U)

12:00pm to 1:15pm

Location:

Manchester Building (room 209), Jerusalem, Israel
Title: Character values on compact simple Lie groups Abstract: This work is part of a joint project with Aner and others to find upper bounds for values of irreducible characters in two related settings: compact simple Lie groups and finite groups of Lie type. I will discuss the first case, presenting bounds of the form $$|\chi(g)| = O(\chi(1)^\alpha),$$
2015 Nov 19

Amitsur Algebra: Avinoam Mann (HUJI), "Irreducible characters of some p-groups"

12:00pm to 1:15pm

Location:

Manchester Building (room 209), Jerusalem, Israel
Abstract: We will discuss the characters of some classes of finite p-groups, in particular groups of maximal class and generalizations, and normally monomial groups.
2016 Mar 29

Dynamics & probability: Paul Nelson (ETH) - Microlocal lifts and quantum unique ergodicity on GL(2,Q_p)

2:00pm to 3:00pm

Location:

Manchester building, Hebrew University of Jerusalem, (Room 209)
Abstract: There are by now several celebrated measure classification results to the effect that a measure is uniform provided it possesses sufficient "invariance" as quantified by stabilizer, entropy, or recurrence. In some applications, part of the challenge is to identify or construct measures to which these hypotheses apply.
2016 Mar 08

Dynamics & probability: Elon Lindenstrauss (Mean dimension and embedding of Z^d actions)

2:00pm to 3:00pm

Location:

Manchester building, Hebrew University of Jerusalem, (Room 209)
2018 Jan 15

Michael Farber: "Robot motion planning and equivariant Bredon cohomology"

9:00am to 11:00am

Location:

IIAS, Feldman Building, Givat Ram

Abstract: The motion planning problem of robotics leads to an interesting invariant of topological spaces, TC(X), depending on the homotopy type of X = the configuration space of the system. TC(X) is an integer reflecting the complexity of motion planning algorithms for all systems (robots) having X as their configuration space. Methods of algebraic topology allow to compute or to estimate TC(X) in many examples of practical interest. In the case when the space X is aspherical the number TC(X) depends only on the fundamental group of X.

2018 Mar 05

HD-Combinatorics Special Day: Samplers in Computer Science (organised by Amnon Ta-Shma)

10:00am to 5:00pm

Location:

IIAS, Feldman Building, Givat Ram
2018 Jan 22

HD-Combinatorics: Frank Calegari, "Methods for computing homology and cohomology"

9:00am to 11:00am

Location:

IIAS, Feldman Building, Givat Ram
2018 Mar 12

HD-Combinatorics Special Day: Cohomology on Sheafs for graphs and complexes (organised by Uriya First)

10:00am to 5:00pm

Location:

IIAS, Feldman Building, Givat Ram
2017 Nov 21

T&G: Semyon Alesker (Tel Aviv University), Calabi type problem for Monge-Ampere equations on HKT manifolds

12:00pm to 1:30pm

Location:

Room 70A, Ross Building, Jerusalem, Israel
Real and complex Monge-Ampere equations play a central role in several branches of geometry and analysis. We introduce a quaternionic version of a Monge-Ampere equation which is an analogue of the famous Calabi problem in the complex case. It is a non-linear elliptic equation of second order on so called HyperKahler with Torsion (HKT) manifolds (the latter manifolds were introduced by physicists in 1990's). While in full generality it is still unsolved, we will describe its solution in a special case and some
2015 Nov 15

Game Theory & Math Economics: Liad Blumrosen (HUJI) - "(Almost) Efficient Mechanisms for Bilateral Trading" (joint work with Shahar Dobzinski)

3:30pm to 4:30pm

Location:

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
We study the simplest form of two-sided markets: one seller, one buyer and a single item for sale. It is well known that there is no fully-efficient mechanism for this problem that maintains a balanced budget. We characterize the quality of the most efficient mechanisms that are budget balanced, and design simple and robust mechanisms with these properties. We also show how minimal use of statistical data can yield good results. Finally, we demonstrate how solutions for this simple bilateral-trade problem can be used as a "black-box" for constructing mechanisms in more general environments.
2016 May 29

Game Theory & Math Economics: Eilon Solan (Tel Aviv University) - "Acceptable Strategy Profiles in Stochastic Games"

4:00pm to 5:00pm

Location:

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
I will present a new solution concept for multiplayer stochastic games, namely, acceptable strategy profiles. For each player $$i$$ and state $$s$$ in a stochastic game, let $$w_i(s)$$ be a real number.
2015 Nov 29

Game Theory & Math Economics: Ran Spiegler (Tel Aviv University and University College London) - "On the "Limited Feedback" Foundation of Boundedly Rational Expectations"

4:00pm to 5:00pm

Location:

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
A common justification for boundedly rational expectations is that agents receive partial feedback about the equilibrium distribution. I formalize this idea in the context of the "Bayesian network" representation of boundedly rational expectations, presented in Spiegler (2015). According to this representation, the decision maker forms his beliefs as if he Öts a subjective causal model - captured by a directed acyclic graph (DAG) over the set of variables - to the objective distribution.
2015 Dec 27

Game Theory & Math Economics: Eyal Winter (HUJI) - "Rule Rationality" (Joint work with Yuval Heller)

4:00pm to 5:00pm

Location:

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
We study the strategic advantages of following rules of thumb that bundle different games together (called rule rationality) when this may be observed by one’s opponent. We present a model in which the strategic environment determines which kind of rule rationality is adopted by the players. We apply the model to characterize the induced rules and outcomes in various interesting environments. Finally, we show the close relations between act rationality and “Stackelberg stability” (no player can earn from playing first). Refreshments available at 3:30 p.m.
2016 Mar 20

Game Theory & Math Economics: Gilad Bavly and Ron Peretz (Bar-Ilan) - "Limits of Correlation with Bounded Complexity"

4:00pm to 5:00pm

Location:

Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
Peretz (2013) showed that, perhaps surprisingly, players whose recall is bounded can correlate in a long repeated game against a player of greater recall capacity. We show that correlation is already impossible against an opponent whose recall capacity is only linearly larger. This result closes a gap in the characterisation of min-max levels, and hence also equilibrium payoffs, of repeated games with bounded recall.