2016 Jan 20

Topology & geometry, Matan Prasma (Radboud University), "Model-categorical cotangent complex formalism"

11:00am to 12:45pm


Ross building, Hebrew University (Seminar Room 70A)
Abstract: One of the first applications of model categories was Quillen homology. Building on the notion of Beck modules, one defines the cotangent complex of an associative or commutative (dg)-algebras as the derived functor of its abelianization. The latter is a module over the original algebra, and its homology groups are called the (Andre'-)Quillen homology. The caveat of this approach is that the cotangent complex is not defined as a functor on the category of all algebras.
2017 Jun 13

Topology and Geometry Seminar: Alexander Caviedes Castro (Tel-Aviv University), "Symplectic capacities and Cayley graphs"

1:00pm to 1:50pm


Ross 70A
Abstract: The Gromov non-squeezing theorem in symplectic geometry states that is not possible to embed symplectically a ball into a cylinder of smaller radius, although this can be done with a volume preserving embedding. Hence, the biggest radius of a ball that can be symplectically embedded into a symplectic manifold can be used as a way to measure the "symplectic size'' of the manifold. We call the square of this radius times the number \pi the Gromov width of the symplectic manifold. The Gromov width as a symplectic invariant is extended through the notion of "Symplectic Capacity".
2018 Apr 16

Combinatorics: Imre Leader (Cambridge) "Decomposing the Complete r-Graph"

11:00am to 12:30pm


IIAS, room 130, Feldman Building, Givat Ram
Speaker: Imre Leader, Cambridge
Title: Decomposing the Complete r-Graph
The Graham-Pollak theorem states that to decompose the complete graph K_n into complete bipartite subgraphs we need at least n−1 of them. What happens for hypergraphs? In other words, suppose that we wish to decompose the complete r-graph on n vertices into complete r-partite r-graphs; how many do we need?
In this talk we will report on recent progress on this problem.
This is joint work with Luka Milicevic and Ta Sheng Tan.
2016 Feb 28

Game theory & economics: Itzhak Gilboa (Tel Aviv, HEC Paris)

3:30pm to 4:30pm


Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
Topic: Weighted Utilitarianism, Edgeworth, and the Market (joint work with Rossella Argenziano)
Place: Elath Hall, 2nd floor, Feldman Building, Edmond Safra Campus
Time: Sunday, March 6, 2016 at 4:00 p.m.
Refreshments available at 3:30 p.m.
2015 Jan 11

Game Theory & Math Economics: Gaëtan FOURNIER (Paris-Sorbonne University) - "Efficiency of Equilibria in Hotelling Games" (joint with Marco Scarsini)

4:00pm to 5:00pm


Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We consider a Hotelling game where a finite number of retailers choose a location, given that their potential customers are distributed on a network. Retailers do not compete on price but only on location. We show that when the number of retailers is large enough, the game admits a pure Nash equilibrium and we construct it. We then compare the equilibrium cost bore by the consumers with the cost that could be achieved if the retailers followed the dictate of a benevolent planner. We look at this efficiency of equilibrium asymptotically in the number of retailers.