Algebraic Geometry Seminar

Department of Mathematics
Princeton University


Fall 2003 Lectures

Regular meeting time: Tuesdays 4:30--5:30 (Tea served at 3:30)
Place: Fine 322

Date Speaker Title
Sep. 23 F. Orgogozo
Princeton
Bloch's conductor formula and Milnor numbers
Sep. 30 Y.Tschinkel
Uni. Goettingen
On the arithmetic of K3 surfaces
Oct.7 O. Fujino
Nagoya and IAS
A canonical bundle formula.
Oct.14 R. Parimala
Tata Inst
Isotropy of quadratic forms over function fields of p-adic curves.
Oct.21 Kiran S. Kedlaya
IAS and MIT
Semistable reduction for p-adic local systems.
Oct.28 Fall Break

Nov.4 Alastair Craw
Stony Brook
Towards the McKay correspondence in all dimensions. For a finite subgroup G of SL(3,C), Bridgeland, King and Reid proved that a particular crepant resolution Y of the quotient C^3/G is "distinguished" in the sense that it is a moduli space of objects on C^3. In addition, they established the McKay correspondence for Y as an equivalence of derived categories. I'll describe recent joint work with Akira Ishii (Kyoto) proving that every crepant resolution of C^3/G is a moduli space of representations of the McKay quiver (for G Abelian), generalising a result by Kronheimer for finite subgroups of SL(2,C). I'll also describe a programme to appropriately generalise the McKay correspondence to higher dimensions.
Nov.11

Nov.18 Linda Chen
Columbia
The orbifold Chow ring of toric Deligne-Mumford stacks. Orbifold cohomology and Chow ring theories have recently been developed -- their invariants coincide with classical invariants of a nice (crepant) resolution of singularities. We introduce a theory of toric Deligne-Mumford stacks, compute their orbifold Chow rings, and give a connection to resolutions of singularities. This is joint work with Lev Borisov and Greg Smith.
Nov.25 Jaroslaw Wlodarczyk
Purdue
Simple Hironaka resolution. Building upon works of O.Villamyor, Encinas-Villamayor and Bierstone-Milman we give a short proof of Hironaka resolution teorems. We put particular emphasis on canonicity and functoriality of the algorithm. Introduced here idea of "Homogenized ideals" gives apriorie canonicity of the resolution procedure and radically simplifies the proof.
Dec.2 Sorin Popescu
Stony Brook
Algebraic Sets of Minimal Degree. Algebraic varieties of minimal degree were classified by Del Pezzo (for surfaces) and Bertini (in all dimensions). For various reasons the notion of ``minimal degree'' is not a very sensible one for algebraic sets in general, but there are other good geometric conditions that mean "minimal degree" in the irreducible case and generalize well. In recent work with Eisenbud, Green and Hulek we have achieved a rather simple classification from which a number of surprising algebraic and geometric results flow. It turns out also that this classification coincides with that of 2-regular reduced ideals.
Dec.9 Gabriele Mondello
Combinatorial and tautological classes on the moduli space of curves. Every presentation of the moduli space of curves gives rise to "natural" cohomology classes. The so-called tautological classes appear in the classical algebro-geometric setting. On the other side, the cellular decomposition of the moduli space via the ribbon graph complex allowed Witten to define some interesting cycles on it, which are called combinatorial. The aim of this talk is to illustrate the main ideas involved in the proof of the so-called Witten-Kontsevich conjecture: combinatorial classes are tautological.
Dec 11-14
Katz Conference, Information


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