| Date |
Time |
Place |
Activity |
Speaker |
Info |
| June 8 |
14:15-15:15 |
KTH 3733 |
Small Talk Seminar |
Runar Ile |
Title: NAK implies exchange. Abstract: Nakayama's lemma is one of the most useful basic results in algebraic geometry. By simple and elementary arguments we will show how a strong version of Nakayama's lemma implies a general «exchange» property of cohomologies. The exchange property is the key ingredient in «cohomology-and-base change» results. |
| June 1 |
14:15-15:15 |
KTH 3733 |
Small Talk Seminar |
Ornella Greco |
Title:Survey on Macaulay's Theorem, Green's Hyperplane restriction theorem and their extension. Abstract: n this talk, we will give an introduction to Macaulay's Theorem, which characterizes the Hilbert fuctions of homogeneous algebras; we will, as well, talk about the Geen's Hyperplane Restriction Theorem, that gives a bound on the hilbert function of the restriction to a general hyperplane. Moreover, we will talk about generalizations of these two thoerems to modules, and to the exterior algebra. |
| May 11 |
14:15-15:15 |
KTH 3733 |
Small Talk Seminar |
David Rydh |
Title: Valuation rings. Abstract: in this talk, I will give an introduction to valuation rings. In particular, I will explain why non-discrete higher rank valuations are necessary in the study of Riemann--Zariski spaces. The plan is to present a large number of examples of valuations on surfaces. |
| May 4 |
14:15-15:15 |
KTH 3733 |
Small Talk Seminar |
Roy Skjelnes |
Ttile: Weil restriction and Fitting Ideals. Abstract: The plan is to define these important objects, and then use the Fitting ideals to describe the Weil restrictions. |
| April 27 |
14:15-15:15 |
KTH 3733 |
Small Talk Seminar |
Wojciech Chacholski |
Title:What I did not know about polynomial rings. Abstract: in the talk I will recall homological properties of graded polynomial rings. The aim is to convince you that these propeties can be proven using elementray observations. It is based on conversations with M. Scolamiero and F. Vacarino. |
| April 11-14 |
|
KTH 3733 |
A small, informal workshop at KTH on the moduli space of curves and its intersection theory. |
|
There will be a few talks (to be announced); mostly, the participants will meet to discuss problems and to try to make progress in solving them.
Participants: O. Bergvall (Stockholm), G. Farkas (Berlin), F. Janda (Zürich), M. Lelli-Chiesa (Berlin), N. Pagani (Hannover), R. Pandharipande (Zürich), D. Petersen (Stockholm), A. Pixton (Zürich), N. Tarasca (Hannover), M. Tavakol (Amsterdam), O. Tommasi (Hannover). Organizer: C. Faber. Supported by the Göran Gustafsson Foundation (UU/KTH). |
| March 30 |
15:00-16:00 |
KTH 3733 |
Small Talk Seminar |
Carel Faber |
Title: Detecting and constructing Teichmüller modular forms. Abstract: A classical Teichmüller modular form is a section on the moduli space M_g of a power of the determinant of the Hodge bundle. Vector-valued Teichmüller modular forms are sections on M_g of the vector bundles obtained by applying Schur functors for irreducible representations of GL(g) to the Hodge bundle. Siegel modular forms, sections on A_g of the corresponding bundles, give Teichmüller modular forms via pull-back to M_g, but for g at least 3 there exist `genuine' Teichmüller modular forms, not obtained via pull-back. Classical Teichmüller modular forms have been studied in detail by Ichikawa. I will try to explain how we have found, in a rather roundabout way, strong indications for the existence of genuine Teichmüller modular forms, in four cases. If time permits, I will discuss how a natural construction appears to produce many Teichmüller modular forms. The construction covers in particular the four cases mentioned. This is work in progress, joint with Jonas Bergström and Gerard van der Geer. |
| March 23 |
14:15-15:15 |
KTH 3733 |
Small Talk Seminar |
Christine Jost |
Titel: Toric vector bundles.
Abstract: Torus-equivariant, or simply toric, vector bundles are known to
have a description in terms of filtrations of vector spaces since the work
of Klyachko in the end of the 90s. I will give an introduction to
Klyachko's description as well as Payne's recent construction of branched
covers of fans associated to toric vector bundles. |
| March 16 |
14:15-15:15 |
KTH 3733 |
Small Talk Seminar |
Dan Petersen |
Title: The yoga of weights.
Abstract: Deligne and Grothendieck realized that the cohomology of
algebraic varieties has a feature not present in the usual cohomology
of spaces: it is made up out of pieces of different "weights". I try
to give some flavor of these ideas. |
| March 9 |
14:15-15:15 |
KTH 3733 |
Small Talk Seminar |
Jack Hall |
Title: Deformation theory via Grothendieck topologies.
Abstract: Some time ago, D. Quillen worked out an elegant framework for the deformation theory of rings using Grothendieck topologies. Recently, J. Wise updated and extended these techniques to include the deformation theory of ringed topoi. I will talk about this circle of ideas with the aim of demystifying how the cotangent complex fits in to the story. |
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