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Autumn Semester 2013

Date / Time Speaker Title Location
* 20 September 2013
14:00-18:00
Details

Algebraic Geometry and Moduli Seminar

Title ETH-ITS Mathematical physics meeting
Speaker, Affiliation
Date, Time 20 September 2013, 14:00-18:00
Location HG G 43
ETH-ITS Mathematical physics meeting
HG G 43
27 September 2013
16:00-17:00 		Dr. Alexandr Buryak
ETH Zürich
Details

Algebraic Geometry and Moduli Seminar

Title Dubrovin-Zhang hierarchy for Hodge integrals
Speaker, Affiliation Dr. Alexandr Buryak, ETH Zürich
Date, Time 27 September 2013, 16:00-17:00
Location HG G 43
Abstract In the talk I will explain that the generating series of the Hodge integrals over the moduli space of stable curves is a solution of a certain deformation of the KdV hierarchy. This hierarchy is constructed in the framework of the Dubrovin-Zhang theory of the hierarchies of the topological type.
Dubrovin-Zhang hierarchy for Hodge integralsread_more
HG G 43
4 October 2013
16:00-17:00 		Iman Setayesh
IPM, Tehran
Details

Algebraic Geometry and Moduli Seminar

Title The combinatoriality of the kappa ring
Speaker, Affiliation Iman Setayesh, IPM, Tehran
Date, Time 4 October 2013, 16:00-17:00
Location HG G 43
Abstract In this talk I will discuss some results about the structure of the kappa ring of \bar{M}_{g,n}, and also some evidence for the combinatoriality of the kappa ring.
The combinatoriality of the kappa ringread_more
HG G 43
* 11 October 2013
09:00-17:00
Details

Algebraic Geometry and Moduli Seminar

Title FIM conference: Moduli space of curves
Speaker, Affiliation
Date, Time 11 October 2013, 09:00-17:00
Location HG G 43
FIM conference: Moduli space of curves
HG G 43
18 October 2013
16:00-17:00 		Prof. Dr. Joseph Ayoub
Universität Zürich
Details

Algebraic Geometry and Moduli Seminar

Title Foliated cohomology
Speaker, Affiliation Prof. Dr. Joseph Ayoub, Universität Zürich
Date, Time 18 October 2013, 16:00-17:00
Location HG G 43
Foliated cohomology
HG G 43
* 22 October 2013
13:30-14:30 		Prof. Dr. Bernd Sturmfels
UC Berkeley and MPI Bonn
Details

Algebraic Geometry and Moduli Seminar

Title Tropicalization of Classical Moduli Spaces
Speaker, Affiliation Prof. Dr. Bernd Sturmfels, UC Berkeley and MPI Bonn
Date, Time 22 October 2013, 13:30-14:30
Location HG G 19.2
Abstract Algebraic geometry is the study of solutions sets to polynomial equations. Solutions that depend on an infinitesimal parameter are studied combinatorially by tropical geometry. Tropicalization works especially well for varieties that are parametrized by monomials in linear forms. Many classical moduli spaces (for curves of low genus and few points in the plane) admit such a representation, and we here explore their tropical geometry. Examples to be discussed include the Segre cubic, the Igusa quartic, the Burkhardt quartic, and moduli spaces of marked del Pezzo surfaces. Matroids, hyperplane arrangements, and Weyl groups play a prominent role. Our favorites are E6, E7 and G32. This is joint work with Qingchun Ren and Steven Sam.
Tropicalization of Classical Moduli Spacesread_more
HG G 19.2
* 22 October 2013
15:00-16:00 		Dr. Noah Giansiracusa
UC Berkeley
Details

Algebraic Geometry and Moduli Seminar

Title A non-reductive GIT approach to the effective cone of \M_{0,n}
Speaker, Affiliation Dr. Noah Giansiracusa, UC Berkeley
Date, Time 22 October 2013, 15:00-16:00
Location HG G 19.2
Abstract I'll discuss joint work with Brent Doran and Dave Jensen in which we introduce a method for systematically studying the effective cone of \bar{M}_{0,n}. An "algebraic uniformization" of this space that we previously constructed translates information about all effective divisors (i.e. the Cox ring) into equivariant information about affine space, and to study effectivity of the rays spanned by divisor classes (i.e. the effective cone) translates naturally into non-reductive GIT stability analysis for this group action on affine space. We see in particular that there are numerous counterexamples to the Castravet-Tevelev hypertree conjecture on Eff(M_{0,n}) and that for all n \ge 7 a surprising discrepancy between the Cox ring and the effective cone emerges.
A non-reductive GIT approach to the effective cone of \M_{0,n}read_more
HG G 19.2
1 November 2013
16:00-17:00 		Prof. Dr. Ivan Smith
Cambridge University
Details

Algebraic Geometry and Moduli Seminar

Title Quadratic differentials as stability conditions
Speaker, Affiliation Prof. Dr. Ivan Smith, Cambridge University
Date, Time 1 November 2013, 16:00-17:00
Location HG G 43
Abstract We will explain why moduli spaces of meromorphic quadratic differentials on Riemann surfaces arise as spaces of stability conditions on triangulated categories. This talk reports on joint work with Tom Bridgeland.
Quadratic differentials as stability conditionsread_more
HG G 43
15 November 2013
16:00-17:00 		Prof. Dr. Stefan Kebekus
Université de Fribourg
Details

Algebraic Geometry and Moduli Seminar

Title Differential forms on singular spaces
Speaker, Affiliation Prof. Dr. Stefan Kebekus, Université de Fribourg
Date, Time 15 November 2013, 16:00-17:00
Location HG G 43
Abstract The talk is concerned with differential forms on log canonical varieties. It is shown that any p-form defined on the smooth locus of a variety with canonical or klt singularities extends regularly to any resolution of singularities. In fact, a much more general theorem for log canonical pairs is established. The proof relies on vanishing theorems for log canonical varieties and on methods of the minimal model program. In addition, a theory of differential forms on dlt pairs is developed. It is shown that many of the fundamental theorems and techniques known for sheaves of logarithmic differentials on smooth varieties also hold in the dlt setting. Applications will be discussed in some detail.
Differential forms on singular spacesread_more
HG G 43
22 November 2013
16:00-17:00 		Dr. Victoria Hoskins
Universität Zürich
Details

Algebraic Geometry and Moduli Seminar

Title Symplectic methods for non-reductive group actions
Speaker, Affiliation Dr. Victoria Hoskins, Universität Zürich
Date, Time 22 November 2013, 16:00-17:00
Location HG G 43
Abstract For complex reductive group actions, the geometric invariant theory quotient is often identified with the symplectic reduction for the associated maximal compact group via the Kempf-Ness Theorem. For non-reductive groups, one can ask whether there is an analogous symplectic picture. In this talk, we describe an approach for certain non-linear actions of the complex additive group on affine spaces. This is joint work in progress with Brent Doran.
Symplectic methods for non-reductive group actionsread_more
HG G 43
29 November 2013
16:00-17:00 		Prof. Dr. Bernd Siebert
Universität Hamburg
Details

Algebraic Geometry and Moduli Seminar

Title Generalized theta functions
Speaker, Affiliation Prof. Dr. Bernd Siebert, Universität Hamburg
Date, Time 29 November 2013, 16:00-17:00
Location HG G 43
Abstract The reconstruction theorem provides canonical maximal degenerations of polarized varieties with effective anticanonical divisor. The starting data is purely combinatorial, a cell complex of integral polyhedra along with charts for the affine structure at the vertices. The construction can be viewed as a non-linear generalization of toric geometry. In the talk I will explain how such degenerations come with a canonical basis of the homogeneous coordinate ring, which in the case of degenerations of abelian varieties agree with classical theta functions. I will also discuss why I believe that these generalized theta functions are the key to understanding many properties of varieties admitting maximal degenerations, including all of the properties relevant to mirror symmetry.
Generalized theta functionsread_more
HG G 43
6 December 2013
16:00-17:00 		Arend Bayer
University of Edinburgh
Details

Algebraic Geometry and Moduli Seminar

Title Birational geometry of moduli of sheaves on K3s via wall-crossing
Speaker, Affiliation Arend Bayer, University of Edinburgh
Date, Time 6 December 2013, 16:00-17:00
Location HG G 43
Abstract A basic question about moduli spaces is to understand its birational geometry and relate it to the geometry of the underlying moduli problem. For moduli spaces of sheaves on K3 surfaces, this can be done completely systematically in terms of wall-crossing for deformations of Bridgeland stability conditions: any minimal model of the moduli space appears as a moduli space of Bridgeland-stable objects in some chamber. As applications, we can answer several open questions on these moduli spaces, e.g. we determine their nef cones, and we prove a conjecture on existence of Lagrangian fibrations. This is based on joint work with E. Macri.
Birational geometry of moduli of sheaves on K3s via wall-crossingread_more
HG G 43
13 December 2013
16:00-17:00 		Dr. Christian Böhning
Universität Hamburg
Details

Algebraic Geometry and Moduli Seminar

Title Rationality problems: a bird's eye view
Speaker, Affiliation Dr. Christian Böhning, Universität Hamburg
Date, Time 13 December 2013, 16:00-17:00
Location HG G 43
Rationality problems: a bird's eye view
HG G 43

Notes: red marked events are important and events marked with an asterisk (*) indicate that the time and/or location are different from the usual time and/or location.

Organisers: Rahul Pandharipande

Archive: SS 25 AS 24 SS 24 AS 23 SS 23 AS 22 SS 22 AS 21 SS 21 AS 20 SS 20 AS 19 SS 19 AS 18 SS 18 AS 17 SS 17 AS 16 SS 16 AS 15 SS 15 AS 14 SS 14 AS 13 SS 13 AS 12 SS 12 AS 11

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