代数幾何学セミナー

過去の記録 ~07/21次回の予定今後の予定 07/22~

開催情報 金曜日 13:30~15:00 数理科学研究科棟(駒場) ハイブリッド開催/117号室
担当者 權業 善範、中村 勇哉、田中 公

過去の記録

2007年10月16日(火)

10:00-12:00   数理科学研究科棟(駒場) 128号室
10月16日開始, 毎週火曜10時から12時の連続講演です. 10月23日と12月4日は休講です.
Dmitry KALEDIN 氏 (Steklov研究所, 東大数理)
Homogical methods in Non-commutative Geometry
[ 講演概要 ]
Of all the approaches to non-commutative geometry, probably the most promising is the homological one, developed by Keller, Kontsevich, Toen and others, where non-commutative eometry is understood as "geometry of triangulated categories". Examples of "geometric" triangulated categories come from representation theory, symplectic geometry (Fukaya category) and algebraic geometry (the derived category of coherent sheaves on an algebraic variety and
various generalizations). Non-commutative point of view is expected to be helpful even in traditional questions of algebraic geometry such as the termination of flips.

We plan to give an introduction to the subject, with emphasis on homological methods (such as e.g. Hodge theory which, as it turns out, can be mostly formulated in the non-commutative setting).

No knowledge of non-commutative geometry whatsoever is assumed. However, familiarity with basic homological algebra and algebraic geometry will be helpful.

2007年10月10日(水)

16:30-17:30   数理科学研究科棟(駒場) 117号室
代数学コロキウムとの合同講演会です. 15時から122号室でKaledinさんの講演があります.

James Lewis 氏 (University of Alberta)
Abel-Jacobi Maps Associated to Algebraic Cycles, I.

[ 講演概要 ]
This talk concerns the Bloch cycle class map from the higher Chow groups to Deligne cohomology of a projective algebraic manifold. We provide an explicit formula for this map in terms of polylogarithmic type currents.

2007年10月10日(水)

15:00-16:00   数理科学研究科棟(駒場) 122号室
Dmitry Kaledin 氏 (Steklov Institute)
p-adic Hodge theory in the non-commutative setting
[ 講演概要 ]
We will explain what is the natural replacement of the notion of Hodge structure in the p-adic setting, and how to construct such a structure for non-commutative manifolds (something which at present cannot be done for the usual Hodge structures, but works perfectly well for the p-adic analog).

2007年09月26日(水)

16:30-18:00   数理科学研究科棟(駒場) 126号室
Grigory Mikhalkin 氏 (Toronto大学)
Floor diagrams and enumeration of tropical curves
[ 講演概要 ]
The enumerative problems considered in this talk are finding the number of curves in projective spaces (over complex, real and tropical numbers) of given genus and degree constrained by certain incidence conditions (e.g. passing via points or lines). Floor diagrams are a combinatorial tool that reduces an enumerative problem in dimension n to the corresponding problem n dimension n-1. Floor diagrams give a constructive (and rather efficient) way to find all tropical curves for a given enumerative problem. And once we have a tropical solution of the problem we can use it to solve the corresponding problems over the complex and real numbers.

2007年09月12日(水)

15:00-18:00   数理科学研究科棟(駒場) 117号室
代数学コロキウムとの合同講演会です.
E. Lau 氏 (Univ. of Bielefeld) 15:00-15:45
Classification of p-divisible groups by displays and duality
T. Zink 氏 (Univ. of Bielefeld) 16:00-16:45
Applications of the theory of displays
E. Looijenga 氏 (Univ. of Utrecht) 17:00-18:00
Presentation of mapping class groups from algebraic geometry
[ 講演概要 ]
A presentation of the mapping class group of a genus g surface with one hole is due to Wajnryb with later improvements due to M. Matsumoto. The generators are Dehn twists defined by 2g+1 closed curves on the surface. The relations involving only two Dehn twists are the familiar Artin relations, we show that those involving more than two can be derived from algebro-geometry considerations.

2007年08月29日(水)

17:00-18:00   数理科学研究科棟(駒場) 128号室
Valery Alexeev 氏 (Georgia大学)
Computations on the moduli spaces of weighted log pairs

2007年08月02日(木)

16:30-18:00   数理科学研究科棟(駒場) 126号室
De-Qi Zhang 氏 (Singapore大学)
Dynamics of automorphisms on algebraic varieties
[ 講演概要 ]
The building blocks of automorphisms / endomorphisms of compact varieties are determined --- an algebro geometric approach towards dynamics.

2007年06月22日(金)

16:30-18:00   数理科学研究科棟(駒場) 118号室
Qi Zhang 氏 (Missouri大学)
Projective varieties with nef anti-canonical divisors
[ 講演概要 ]
Projective varieties with nef anti-canonical divisors appear naturally in the minimal model program and the theory of classification of higher-dimensional algebraic varieties. In this talk we describe a comprehensive approach to birational geometry of log canonical pair (X, D) with nef anti-canonical class -(K_X+D). In particular, We present two theorems on the birational structure of the varieties. We will also discuss some recent results and new aspects of the subject.

2007年05月15日(火)

14:30-16:00   数理科学研究科棟(駒場) 122号室
いつもと時間・曜日・場所が異なります。
Mikhail Kapranov 氏 (Yale 大学)
Riemann-Roch for determinantal gerbes and smooth manifolds
[ 講演概要 ]
A version of the Riemann-Roch theorem for curves due to Deligne, describes the determinant of the cohomology of a vector bundle E on a curve.
If one realizes E via the Krichever construction, the determinant of the cohomology becomes a Hom-space in the determinantal gerbe for the vector space over the field of power series. So one has a ``local" Riemann-Roch problem of description of this gerbe itself. The talk will present the results of a joint work with E. Vasserot describing the class of such a gerbe in a family which geometrically can be seen as a circle fibration. This can be further generalized to the case of a fibration with fibers being smooth compact manifolds of any dimension d (joint work with P. Bressler, B. Tsygan and E. Vasserot).

2007年05月07日(月)

16:30-18:00   数理科学研究科棟(駒場) 122号室
謝啓鴻(Xie Qihong) 氏 (東大・数理)
Pathologies on ruled surfaces in positive characteristic
[ 講演概要 ]
We discuss some pathologies of log varieties in positive characteristic. Mainly, we show that on ruled surfaces there are counterexamples of several logarithmic type theorems. On the other hand, we also give a characterization of the counterexamples of the Kawamata-Viehweg vanishing theorem on a geometrically ruled surface by means of the Tango invariant of the base curve.

2007年03月26日(月)

15:30-17:00   数理科学研究科棟(駒場) 128号室
Professor Caucher Birkar 氏 (University of Cambridge)
Existence of minimal models and flips (3rd talk of three)

2007年03月22日(木)

10:30-12:00   数理科学研究科棟(駒場) 128号室
Professor Caucher Birkar 氏 (University of Cambridge)
On boundedness of log Fano varieties (2nd talk of three)

2007年03月20日(火)

16:30-18:00   数理科学研究科棟(駒場) 128号室
Professor Caucher Birkar 氏 (University of Cambridge
)
Singularities and termination of flips (1st talk of three)

2007年01月26日(金)

16:30-17:30   数理科学研究科棟(駒場) 128号室
Professor Frans Oort
(Department of Mathematics
University of Utrecht
)
Irreducibility of strata and leaves in the moduli space of
abelian varieties I (a survey of results)

2006年12月08日(金)

15:00-16:25   数理科学研究科棟(駒場) 126号室
Stefan Kebekus 氏 氏 (Mathematisches Institut
Universität zu Köln
)
Rationally connected
foliations

2006年12月04日(月)

16:30-18:00   数理科学研究科棟(駒場) 126号室
Professor Burt Totaro



(University of Cambridge)

When does a curve move on a surface, especially over a finite field?




2006年11月13日(月)

16:30-18:00   数理科学研究科棟(駒場) 126号室
青木昌雄 氏 (京大数理研)
Hom stacks and Picard stacks

2006年10月18日(水)

16:00-18:15   数理科学研究科棟(駒場) 122号室
E. Esteves 氏 (IMPA) 16:00-17:00

Jets of singular foliations and applications
to curves and their moduli spaces

F. Zak 氏 (Independent Univ. of Moscow) 17:15-18:15
Dual varieties, ramification, and Betti numbers
of projective varieties

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