I will explain the notion of a homotopy quotient of an operad providing different examples of operads of compactified moduli spaces of genus zero curves with marked points: including the space of complex curves (math.arXiv:1206.3749), the real loci of the complex one (arXiv:math/0507514) and the noncommutative …
Salmon and Cayley proved the celebrated 19th century result that a smooth cubic surface over the complex numbers contains exactly 27 lines. By contrast, the count over the real numbers depends on the surface, and these possible counts were classified by Segre. A number of researchers have recently made the striking observation that Segre’s work shows a certain signed count is always 3. In my talk, I will explain how to extend this result to an arbitrary field.
Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We consider the problem of maximizing the revenue from selling a number of goods (or items). In this talk we will focus on approximation results and on the "menu-size" as a measure of auction complexity which affects the revenue. * All the relevant concepts will be introduced in the talk.* The talk is mostly independent of the talk given earlier this year.
Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
Guided by several key examples, we formulate a definition of essential sequential equilibrium for multi-stage games with infinite type sets and infinite action sets, and we prove its general existence.
Elath Hall, 2nd floor, Feldman Building, Edmond J. Safra Campus
We discuss a new class of indices taking into account agents'preferences to coalesce.An axiomatization of these indices are presented.These indices are used to evaluate power distribution in Russian parliament in new era and in Empire period, in the Reichstag of Weimar Republic, in IMF, in Russian banks.
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.
Abstract: In this talk, I will introduce diffeological spaces and some (co)homology theories on these spaces. I will also talk on Thom-Mather spaces and their (co)homology in the diffeological context.
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".
Speaker: Imre Leader, Cambridge
Title: Decomposing the Complete r-Graph
Abstract:
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.
