# Events

# Events 2007

**Intercity Seminar Algebra and Geometry
**

*December 14th, 2007*

**Schedule**

11:00-12:45, Daniel Huybrechts: *Derived equivalences and stability conditions (mainly for K3 surfaces)*

14:00-15:45, Michel van den Bergh: *3-dimensional flops and non-commutative algebras*.

In the evening of the 14th we plan to have dinner in Amsterdam with the speakers. If you want to join us, please let me know (bmoonen@science.uva.nl), preferably before Wednesday 12 December.

**2007 Twente Conference on Lie Groups: Dec 12-14
**

*December 12th, 2007*

The 2007 Twente Conference on Lie Groups will take place on December 12-14, 2007 at Twente University

Organizer : Gerard Helminck

Confirmed speakers include:

V. Golovko, D. Gurevich, A.G. Helminck, E. Horozov, M. Iorgov, M. Kazarian, A. Khoroshkin, S. Khoroshkin, S. Lando, A. Marshakov, O. Morozov, Yu. Neretin, A. Unterberger.

To register for the 2007 Twente Conference on Lie Groups, please send an e-mail to Gerard Helminck: helminckgf@ewi.utwente.nl

**GQT-Colloquium
**

*November 30th, 2007*

KdV Institute room P.227

11:15-12:15 Elmar Schrohe: Index Theory for Boundary Value Problems via Continuous Fields of C*-algebras.

13:30-14:30 Eric Rains: Elliptic hypergeometric integrals

15:00-16:00 Claus Hertling: Oscillating integrals and tt* geometry.

**Speaker: Claus Hertling
**

*November 29th, 2007*

Geometry and Topology seminar: Time: 11.00, Location: Room 611B

Speaker: Claus Hertling (Mannheim, Germany)

Title: Distinguished bases and Stokes matrices for the simple and the simple-elliptic singularities.

**Intercity Seminar Algebra and Geometry
**

*November 23rd, 2007*

University of Amsterdam, KdV Institute (= Euclides building, = Building P)

**Schedule**

11:00-12:45, Jan Stienstra: *Stability conditions*

14:00-15:45, Eduard Looijenga: *The Bondal-Orlov conjecture, and Bridgeland’s theorem for 3-folds*

**Intercity Seminar Algebra and Geometry
**

*November 2nd, 2007*

Radboud University Nijmegen, Huygens Building, Room HG00.310

**Schedule**

11:00-12:45, Jochen Heinloth: *Semi-orthogonal decompositions and t-structures*

14:00-15:45, Alex Quintero: *The McKay correspondence*

**Intercity Seminar Algebra and Geometry
**

*October 12th, 2007*

Leiden University

**Schedule**

11:00-12:45, Ben Moonen: *Orlov’s theorem and reconstruction results*

14:00-15:45, Jozef Steenbrink: *An introduction to the minimal model program*

**Intercity Seminar Algebra and Geometry
**

*September 28th, 2007*

The IC-seminar Algebraic Geometry is devoted to Derived categories and stability conditions will meet in Utrecht:

**Schedule**

11:00-12:45 Bas Edixhoven: General Introduction

14:00-15:45 Gerard van der Geer: Mukai’s results for abelian varieties and K3 surfaces

Location: Buys Ballot Laboratory , Room BBL 106, For more information see the seminar list or click on the header.

**Promotie Rogier Bos
**

*September 28th, 2007*

On Friday 28 September, 15:30, Rogier Bos will defend his thesis at the Radboud University Nijmegen with the title “Groupoids in Geometric Quantization”. Promotor: Prof. dr. Klaas Landsman. Before the ceremony there will be a small symposium with three talks: 10:00-10:45 Jean Renault (Orleans): Cartan subalgebras in C*-algebras 11:00-11:45 Gijs Tuynman (Lille): The Lagrange formalism: a human mistake? 14:00-14:45 Ieke Moerdijk (Utrecht): Lie algebroids and the Milnor-Moore Theorem The talks will be in room HG 00.065.

**Farewell symposium Rainer Kaenders
**

*September 27th, 2007*

Dr. Rainer Kaenders wordt per 1 oktober hoogleraar in Keulen, en zal Nijmegen dus verlaten. Zijn vertrek zal worden opgeluisterd met een Wiskunde Onderwijs middag.

Programma:

15:00 uur: Ontvangst met koffie en thee in de hal van het Huygensgebouw

15:45-17:30: Voordrachten in HG00.303 . Prof. dr. Jan van de Craats, Het nieuwe rekenen, Drs. Aad Goddijn, Het misverstand, Wiskunde Dr. Leon van den Broek, Het beweegt

17:30-19:00: Borrel in de vide van het Huygensgebouw

**Day on Algebraic Topology in Utrecht
**

*September 19th, 2007*

On September 19, a small symposium will be held on topics in Algebraic Topology.

**Schedule**

9.45 – 10.00 : Coffee

10.00 – 11.00 : Kathryn Hess (Lausanne): “Koszul complexes and homotopy morphisms”

11.15 – 12.15 : Tom Leinster (Glasgow): “Homotopy algebras for operads”

Lunch

14.00 – 15.00 : Jiri Rosicky (Brno): “Combinatorial model categories”

Tea

15.30 – 16.30 : Clemens Berger (Nice): “The lattice path operad”

The lectures will take place in BBL (Buys-Ballot Lab) , zaal 361. All interested are welcome to attend!

**Promotie Ittay Weiss
**

*September 18th, 2007*

Ittay Weiss will defend his thesis “Dendroidal Sets” at 14.30 in the Academiegebouw Promotor is Prof.dr. I. Moerdijk.

**GQT-Colloquium
**

*September 14th, 2007*

GQT colloquium, and kickoff of the Intercity Seminar on “Derived categories and stability conditions”

Location: RU Nijmegen, Huygensgebouw and Linnaeusgebouw

**Speakers**

Richard Thomas (Imperial College, London)

Lutz Hille (Univ. Bielefeld)

Eric Opdam (UvA)

**Schedule**

10:30 – 11:00 Coffee

11:00 – 12:15 Lutz Hille: Strongly exceptional sequences of line bundles on toric varieties, Huygensgebouw, HG00.062

12:15 – 14:00 Lunch break

14:00 – 15:15 Eric Opdam: Category O for rational Cherednik algebras, Linnaeusgebouw, N6

15:15 – 15:30 Coffee

15:30 – 16:45 Richard Thomas: Counting curves and stability of ideal sheaves, Linnaeusgebouw, N6

16:45 – 18:00 Reception

**Geometric Aspects of Analysis and Mechanics, Hans Duistermaat 65th Birthday Conference
**

*August 20th, 2007*

Speakers include: Michael Atiyah, Nicole Berline, Jean-Michel Bismut, Yves Colin de Verdire, Richard Cushman, Nils Dencker, F. Alberto Grunbaum, Victor Guillemin, Tara Holm, Lisa Jeffrey, Eugene Lerman, Eckhard Meinrenken, Jiang-Hua Lu, Richard Melrose, Paul-Emile Paradan, Isadore Singer, Reyer Sjamaar, Johannes Strand, Gunther Uhlmann, San Vũ-Ngọc, Alan Weinstein

**Talk Christian Blohmann: Differentiable stacks and noncommutative geometry
**

*June 28th, 2007*

Christian Blohmann (University of California, Berkeley) will speak on `Differentiable stacks and noncommutative geometry’

**Abstract**: Differentiable stacks and noncommutative geometry are alternative methods to study geometric situations which are considered to be pathological in the sense of ordinary differential geometry, such as non-smooth quotients of differentiable manifolds or singularities of gauge fields. I will show how viewing these two approaches as dual to each other leads to a generalization of Hopf algebras and to Lie theory on differentiable stacks.

**Talk Sergey Shadrin: Givental symmetries of tautological equations.
**

*June 26th, 2007*

Dr Sergey Shadrin (University Zurich) speaks Tuesday June 26 11:00-12:00 in Room K8b on “Givental symmetries of tautological equations”.

**Abstract**: I am going to dicsuss the system of PDEs that is called tautological equations. It comes from relations among natural classes in the cohomology of the moduli spaces of curves, and it can serve as a system of axioms for the correlators of topological conformal field theory. This system of PDEs has a huge group of symmetries that was discovered by Givental in genus 0. He proposed to quantize its action, and it was proved by Faber, myself, and Zvonkine that the quantized action also preserves the whole system of tautological relations in all genera.

**Talk Boris Shoikhet: “Koszul duality in deformation quantization”
**

*June 20th, 2007*

Boris Shoikhet (Univ de Luxembourg) will speak on Wednesday June 20 (14:00-15:00) in Room K8b on “Koszul duality in deformation quantization”,

**Abstract**: Let alpha be a polynomial Poisson bivector on a vector space V. Then Kontsevich constructs a star-product f * g on S(V^*), polynomial functions on V. We construct from alpha another algebra by generators and relations. We prove that this algebra obeys the Poincare-Birkhoff-Witt property. Even in the classical case we found a new, cohomological, proof of the PBW theorem, which shares some light on this theorem. We conjecture that the constructed algebra is isomorphic to the Kontsevich star-algebra. We discuss this conjecture, and its relation on our recent preprint math.0706.1333 on an explicit construction of the Quillen localization.

**Talk Sergey Natanzon : Singularities and noncommutative Frobenius manifolds
**

*June 14th, 2007*

Thursday June 14 from 13:00-14:00 in K11 there is a talk:

Speaker: Sergey Natanzon (Independent University Moscow) will speak on “Singularities and noncommutative Frobenius manifolds”

**Abstract**: We prove that quaternion miniversal deformations of the A_n singularity possess a structure of noncommutative Frobenius manifold in the sense of an extended cohomological field theory.

**From Tate Curves to Zariski-Riemann Spaces: A Crash Course in Rigid Geometry by Fumiharu Kato (Kyoto)
**

*June 7th, 2007*

This series of lectures provides an introduction to rigid geometry with special emphasis on its birational-geometric aspects.

Rigid geometry, often spelled as rigid analytic geometry, is an algebro-geometric framework that allows one to mimic the usual analytical approach to varieties over the complex numbers for varieties defined over, say, p-adic fields. The typical `analytical’ features of rigid geometry can be seen in Tate’s uniformization of elliptic curves, the so-called Tate curves, in which certain infinitudes, such as quotient by infinite groups, infinite power series, etc., make perfect sense. Later, M. Raynaud discovered that rigid geometry has a strong relationship with the geometry of formal schemes.

Even after this historic shift from analytic geometry to algebraic geometry, rigid geometry still suffered from a serious deficiency of `visualization’, which would bring an intuitive understanding of the spaces that appear. The original rigid geometry failed to have a correct notion of `points’. The correct `points’, have been found independently by several people, such as R. Huber and K. Fujiwara. Fujiwara’s theory, in particular, takes up Zariski’s viewpoint of classical birational geometry, and provides the desired visualization by a formal geometric analogue of the so-called Zariski-Riemann spaces.

**Plan for the lectures**

(1) Introduction: Tate curves;

(2) Playing around with the analytic projective line;

(3) Rigid geometry by Tate and Raynaud;

(4) Coherent topological spaces and valuative topological spaces;

(5) Zariski’s birational geometry;

Nagata’s embedding theorem;

Flattening theorem;

(6) Formal geometry and rigid geometry: Zariski-Riemann triple;

(7) GAGA.

**Schedule** The five lectures take place from 10-12 a.m. in room K8b (basement) of the Mathematical Institute of the University of Utrecht on the following days: Thursday 7th, Tuesday 12th, Thursday 14th, Tuesday 19th, Thursday 21st of June, 2007.

Everybody is welcome! More information: contact Gunther Cornelissen at cornelis@math.uu.nl.

**Talk by Raf Blockland: An introduction to Calabi Yau Algebras
**

*June 7th, 2007*

Raf Bocklandt (Universiteit Gent) will talk this Thursday, June 7, 10:00-11:00 in Utrecht Room M204 (Minnaert Building) on: An introduction to Calabi Yau Algebras. Abstract: We will show how Calabi Yau Algebras naturally turn up in geometrical problems connected to Kleinian Singularities and String theory. Also we will give some classification results for these algebra

**Nijmegen Singularity Days, June 4th-5th
**

*June 4th, 2007*

Organizers: Dirk Siersma, Joseph Steenbrink

This workshop will also be a meeting point of the

* INTAS project Singularities, Bifurcations and Monodromy

* NWO, Russia project, Geometry and Singularity Theory in Mathematical Physics

The workshop is funded by these projects and has additional funding from the Mathematical Research Institute MRI and the Fellowship for Geometry and Quantum Theory GQT.

**Nijmegen Geometry Days May 31th-June 2nd (in honour of Joseph Steenbrink)
**

*May 31st, 2007*

In honour of Joseph Steenbrink on his 60th birthday.

**Speakers
**Robbert Dijkgraaf, Amsterdam

Luc Illusie, Parijs

Theo de Jong, Mainz

Eduard Looijenga, Utrecht

Andras Nemethi, Columbus

Frans Oort, Utrecht

Chris Peters, Grenoble

Morihiko Saito, Kyoto

Duco van Straten, Mainz

Orsola Tommasi, Hannover

Claire Voisin, Parijs

Steve Zucker, Baltimore

**Scientific Commitee:**

Gerard van der Geer, Amsterdam

Gert Heckman, Nijmegen

Eduard Looijenga, Utrecht

Ben Moonen, Amsterdam

Dirk Siersma, Utrecht

**Local Organisers:**

Gert Heckman, G.Heckman@math.ru.nl

Frans Clauwens, F.Clauwens@math.ru.nl

Roel Willems, R.Willems@math,ru.nl

**Secretary:**

Greta Oliemeulen, maths@math.ru.nl

024-3652986

All lectures will be held in the Huygens Building (HG00.307) of the Radboud University of Nijmegen.

**A. Gorinov in UU geometry and topology seminar NOTE: 10/5
**

*May 10th, 2007*

**Title:** Rational cohomology of the moduli spaces of pointed genus 1 curves

**Time:** Thursday May 10, 14:00-15:00

**Place:** Room 611B of the Mathematics Building, Utrecht

**S. Duzhin in UU geometry and topology seminar 26/4
**

*April 26th, 2007*

**Title:** Geometrization conjecture and Perelman’s work

**Time:** Thursday April 26, 14:00-15:00

**Place** Room 611B of the Mathematics Building, Utrecht

**Special Seminar talk by Konstantin Styrkas 19/4 at UU
**

*April 19th, 2007*

**Title:** Resonance relations, holomorphic trace functions and hypergeometric solutions to qKZB equations.

**Time:** Thursday April 19, 10:00-11:00

**Place:** Room 611B of the Mathematics Building, Utrecht

**Joint Math-Physics seminar in Utrecht
**

*April 13th, 2007*

**Program**

14:00 **Vicente Cortes** (Univ. Hamburg)

*Cones over pseudo-Riemannian manifolds
*By a classical theorem of Gallot (1979), a Riemannian cone over a complete Riemannian manifold is either flat or has irreducible holonomy. We consider metric cones with reducible holonomy over pseudo-Riemannian manifolds and obtain local and global structure theorems.

15:00 Coffee Break

15h15

**J. Stienstra**(Univ. Utrecht)

*Geometric structures related to AdS/CFT*

I will discuss connections (found in physics papers) between Sasaki-Einstein 5-folds on the one hand and quivers on the other hand. This will also involve intrigueing viewpoints on zero loci of 2-variable Laurent polynomials.

16:15 Borrel

**Conference in honour of Richard Cushman (March 26-30)
**

*March 26th, 2007*

**GQT colloquium (Amsterdam). Speakers: S. Kato, E. Looijenga, B. Nienhuis.
**

*March 23rd, 2007*

**Location:** University of Amsterdam, KdV Institute for Mathematics, Plantage Muidergracht 24, lecture room P.017.

**Schedule**

**11.15-12.15** Bernard Nienhuis (UvA)

Title: Statistical lattice models on a cylinder.

**12-15-13.30** Lunch

**13.30-14.30** Syu Kato (University of Tokyo, Japan)

Title: An exotic Deligne-Langlands correspondence for symplectic groups.

**14.30-15.00** Coffee and tea.

**15.00-16.00** Eduard Looijenga (UU)

Title: The moduli space of curves—a meeting point of algebraic geometers and geometric topologists.

**16.00–** Reception

**Conference on Combinatorics and Physics
**

*March 19th, 2007*

Date: **March 19-23, 2007**

If you want to participate please send a short message to: combphys07@mpim-bonn.mpg.de

More information: see website

**ymposium at the closing of the FOM/GBE programme on Mathematical Physics (speakers include Atiyah, Penrose, Yoccoz, Werner)
**

*March 9th, 2007*

On 9 March 2007 the FOM/GBE programme Mathematical Physics will end festively with an international symposium in the Keizersgrachtkerk in Amsterdam.

Speakers include **Sir Michael Atiyah, Sir Roger Penrose, Jean-Christophe Yoccoz** and **Wendelin Werner**.

The final programma will be announced mid-January. Registration will open around that time too. More information can be found in due time on the FOM-website.

**Two talks in Amsterdam (KdV); speakers Vicor Nistor and Ralf Meyer
**

*March 6th, 2007*

On March 6 Victor Nistor and Ralf Meyer will each give a talk at the KdV institute.

**Schedule
**15-16: Victor Nistor (Penn State University), “Analysis on Lie manifolds, well posedness on polyhedral domains, and optimal rates of convergence”.

16-17: Ralf Meyer (Georg-August-Universitt Goettingen), Embeddings of derived categories.

**Place**: Room 3.85, building J/K Valckenierstraat 65, 1018 XE Amsterdam.

**Utrecht General Colloquium talk by Arthemy Kiselev (IHES): Pre-Hamiltonian formalism for integrable nonlinear systems**

*February 22nd, 2007*

**Schedule**

15:00 (Eigenruimte) Tea/Coffee and cookies

15:3–16:30 (K11) General Mathematical Colloquium

**Arthemy Kiselev** (IHES):* Pre-Hamiltonian formalism for integrable nonlinear systems*

**Lecture by Yuri Berest (Cornell University and IHES)
**

*February 22nd, 2007*

**Title:** Ideals of rings of differential operators on algebraic curves.

**Time:** 11.00-12.00

**Location:** Amsterdam, KdV Institute, room P.016.

**GQT colloquium RU (Nijmegen); Speakers: Bunke, Marcolli, Meyer
**

*February 9th, 2007*

For further information see the GQT colloquium page.

**Utrecht General Colloquium talk by Eric Opdam (UvA): Euler-Poincare formula for tempered characters of affine Hecke algebras**

*February 1st, 2007*

**Schedule**

15:00 (Eigenruimte) Tea/Coffee and cookies

15:30–17:15 (Minnaert 211) General Mathematical Colloquium

**Eric Opdam** (UvA): *Euler-Poincare formula for tempered characters of affine Hecke algebras
part 1: The Plancherel formula for Hecke algebras: motivation and basic results
part 2: Index functions and formal dimensions*

**Utrecht General Colloquium talk by Walter van Suijlekom (RU): Renormalization of gauge fields: A Hopf algebra approach**

*January 18th, 2007*

**Schedule**

15:00 (Eigenruimte) Tea/Coffee and cookies

15:3–16:30 (K11) General Mathematical Colloquium

**Walter van Suijlekom** (RU): *Renormalization of gauge fields: A Hopf algebra approach*