Current Seminars
updated 2/27/ 2002
As of February 27 - March 1
Department Colloquium
Topic: On the Monge Ampere equation in periodic media
Presenter: Luis A. Caffarelli, University of Texas at Austin
Date: Wednesday, February 27, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Discrete Mathematics Seminar
Topic: Bipartite cuts and judicious partitions in graphs without short cycles
Presenter: Michael Krivelevich, Tel Aviv University
Date: Thursday, February 28, 2002, Time: 2:00 p.m., Location: Fine Hall 224
Ergodic Theory and Statistical Mechanics Seminar *** Rescheduled from February 21, 2002
Topic: Limiting distributions for special last passage percolation models Part I
Presenter: Jinho Baik, Princeton University and the Institute for Advanced Study
Date: Thursday, February 28, 2002, Time: 2:00 p.m., Location: Fine Hall 601
Abstract: A few special last passage percolation models have exact determinantal formulas for their distribution functions using ideas from combinatorics. In the first talk, we discuss the algebraic steps to obtain the determinantal formulas. In the second talk, we analyze the determinants asymptotically and obtain the limiting distributions. We also consider their relation to random matrix theory.
Topology Seminar
Topic: Mapping class groups, Lefschetz fibrations and Stein fillings
Presenter: Andras Stipsicz, ELTE/Princeton
Date: Thursday, February 28, 2002, Time: 4:00 p.m., Location: Fine Hall 314
Princeton University/IAS Number Theory Seminar
Topic: Automorphisms of even unimodular lattices
Presenter: Benedict Gross, Harvard University
Date: Thursday, February 28, 2002, Time: 4:30 p.m., Location: IAS SH-101
Graduate Student Seminar
Topic: Cryptologic Properties of GammaPi Class
Presenter: Seth Patinkin, Princeton University
Date: Friday, March 1, 2002, Time: 1:00 p.m., Location: Fine Hall 1001
Abstract: I will present a new cryptologic primitive which may be used in a variety of contexts, both symmetric and asymmetric. This method is based on the construction of a class of mappings from the space of real-entry matrices to the space of characteristic functions defined on bounded, finite-dimensional geometric regions. Novelty, computational infeasibility, efficiency, and known attacks shall be addressed.
Joint Princeton University/IAS/Rutgers Non-Linear Analysis Seminar *** Note special day and time and location
Topic: Constraint methods for nonlinear homogenization in periodic and random media, Part II'
Presenter: Luis A. Caffarelli, University of Texas at Austin
Date: Friday, March 1, 2002, Time: 4:30 p.m., Location: Hill Center Room 705 , Rutgers University
March 4 - 8
Algebraic Geometry Seminar *** Please note special date, time, and location
Topic: Differential geometry of gerbes, II
Presenter: William Messing, University of Minnesota
Date: Monday, March 4, 2002, Time: 4:00 p.m., Location: Fine Hall 322
Analysis Seminar
Topic: TBA
Presenter: Fabrice Planchon, Université Pierre et Marie Curie
Date: Monday, March 4, 2002, Time: 4:00 p.m., Location: Fine Hall 314
PACM Colloquium
Topic: Solving Differential Equations Without the Equations
Presenter: William Gear, NEC Research
Date: Monday, March 4, 2002, Time: 4:00 p.m., Location: Fine Hall 214
Algebraic Geometry Seminar
Topic: On the effective cones of moduli spaces
Presenter: Brendan Hassett, Rice University
Date: Tuesday, March 5, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: The cone of effective divisors on a smooth projective variety has many properties which are analogous to the cone of effective curves. To understand the cone geometrically, it is necessary to classify its `coextremal rays', generating curve classes of the dual cone corresponding to distinguished fibrations on the variety. We compute these rays for several moduli spaces of curves and give applications to the study of rational points.
CR Seminar
Topic: The half-torsion of a Bernstein-Gelfand-Gelfand diagram
Presenter: Tom Branson, University of Iowa
Date: Tuesday, March 5, 2002, Time: 4:00 p.m., Location: Fine Hall 401
Abstract: Let $D$ be a conformally invariant differential operator with suitable ellipticity properties. A choice of a Riemannian metric on a compact manifold assigns a (pure point) spectrum to $D$. This spectrum, and therefore spectral invariants like the functional determinant det$(D)$, are not {\it conformal} invariants: they move as we move within a conformal class of metrics. However they lead to nice max/min problems which tend to pick out distinguished metrics within a conformal class, since one can write a nice (Polyakov) formula for the quotient of such determinants in conformally related metrics; this has been an important theme in string theory. Though the Laplacians of the de Rham complex are not conformally invariant, a certain combination of their determinants admits a nice Polyakov formula. In even dimension $n=2m$ this is $\prod_{k=0}^{m-1}({\rm det}\Delta_k)^{(-1)^k(m-k)}$. This {\it half-torsion} has considerably less invariance than the Reidemeister-Ray-Singer torsion. This may be viewed as a functional determinant for the Maxwell operator that ``feels'' effect of that operator's gauge (as well as conformal) invariance. We show that the proper setting for the above principle is that of generalized Bernstein-Gelfand-Gelfand (gBGG) sequences, and that each of these has a half-torsion with a Polyakov formula, at least in the locally conformally flat case. (The exponents are now not just $(-1)^k(m-k)$, but are determined by the conformal weights of bundles in the gBGG sequence.) For example, the next most elementary gBGG sequence (after the de Rham complex) is the metric deformation complex, an important construct in quantum gravity.
Department Colloquium
Topic: TBA
Presenter: Ingrid Daubchies, Princeton University
Date: Wednesday, March 6, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Discrete Mathematics Seminar
Topic: TBA
Presenter: John Conway, Princeton University
Date: Thursday, March 7, 2002, Time: 2:00 p.m., Location: Fine Hall 224
Ergodic Theory and Statistical Mechanics Seminar *** Rescheduled from February 28, 2002
Topic: Limiting distributions for special last passage percolation models Part II
Presenter: Jinho Baik, Princeton University and the Institute for Advanced Study
Date: Thursday, March 7, 2002, Time: 2:00 p.m., Location: Fine Hall 601
Abstract: A few special last passage percolation models have exact determinantal formulas for their distribution functions using ideas from combinatorics. In the first talk, we discuss the algebraic steps to obtain the determinantal formulas. In the second talk, we analyze the determinants asymptotically and obtain the limiting distributions. We also consider their relation to random matrix theory.
Topology Seminar
Topic: Torsion invariants in symplectic Floer theory
Presenter: Yi-Jen Lee, Princeton University
Date: Thursday, March 7, 2002, Time: 4:00 p.m., Location: Fine Hall 314
Princeton University/IAS Number Theory Seminar
Topic: New Upper Bounds on Sphere Packing
Presenter: Henry Cohn, Microsoft and the American Institute of Mathematics (AIM)
Date:
Thursday, March 7, 2002, Time: 4:30, Location: Fine
Hall 322
Abstract: We develop an analogue for sphere packings of the linear programming bound
for error-correcting codes, and use it to improve the known upper bounds for the density of sphere packings in dimensions 4 through 36. We conjecture
that our approach can be used to solve the sphere packing problem in dimensions 8 and 24; at the very least, the numerical bounds obtained come
very close to equality. (This is joint work with Noam Elkies.)
Geometric Analysis Seminar
Topic: Cohomology ring of crepant resolutions of orbifolds
Presenter: Ruan Yongbin, University of Wisconsin and Hong Kong University of Science and Technology
Date: Friday, March 8, 2002, Time: 3:00 p.m., Location: Fine Hall 314
March 11 - 15
Analysis Seminar
Topic: TBA
Presenter: Alexandru Ionescu, University of Wisconsin
Date: Monday, March 11, 2002, Time: 4:00 p.m., Location: Fine Hall 314
PACM Colloquium
Topic: Moving Mesh Methods Based on Harmonic Maps
Presenter: Pingwen Zhang, Peking University and Princeton University
Date: Monday, March 11, 2002, Time: 4:00 p.m., Location: Fine Hall 214
Algebraic Geometry Seminar
Topic: Fukaya categories and deformations
Presenter: Paul Seidel, the Institute for Advanced Study
Date: Tuesday, March 12, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Mathematical Physics Seminar
Topic: Coherent State Path Integrals without Resolutions of Unity
Presenter: John Klauder, University of Florida, Gainesville
Date: Tuesday, March 12, 2002, Time: 4:30 p.m., Location: Jadwin A06
Abstract: From the very beginning, coherent state path integrals have always relied on a coherent state resolution of unity for their construction. By choosing an inadmissible fiducial vector, a set of ``coherent states'' spans the same space but loses its resolution of unity, and for that reason has been called a set of weak coherent states. Despite having no resolution of unity, it is nevertheless shown how the propagator in such a basis may admit a phase-space path integral representation in essentially the same form as if it had a resolution of unity.
Discrete Mathematics Seminar
Topic: Separating random points
Presenter: Van Vu, University of California, San Diego
Date: Thursday, March 14, 2002, Time: 2:00 p.m., Location: Fine Hall 224
Joint Princeton University/IAS/Rutgers Non-Linear Analysis Seminar
Topic: Global existence and convergence for a fourth order flow in conformal geometry
Presenter: Simon Brendle, University of Tuebingnon
Date: Thursday, March 14, 2002, Time: 4:00, Location: Fine Hall 214
Princeton University/IAS Number Theory Seminar
Topic: TBA
Presenter: Florian Pop, University of Bonn and the Institute for Advanced Study
Date: Thursday, March 14, 2002, Time: 4:30, Location: IAS SH-101
Geometric Analysis Seminar
Topic: On the Singular Set of J-holomorphic Maps
Presenter: Tristan Riviere, ETH (Swiss Federal Institute of Technology, Zurich)
Date: Friday, March 15, 2002, Time: 3:00 p.m., Location: Fine Hall 314
March 18 - 22
PACM Colloquium
Topic: Local Discontinuous Galerkin Methods for Partial Differential Equations with Higher Order Derivatives
Presenter: Chi-Wang Shu, Brown University
Date: Monday, March 18, 2002, Time: 4:00 p.m., Location: Fine Hall 214
Mathematical Physics Seminar *** Please note change in date from February 26, 2002
Topic: The Cauchy Problem for a Dynamical Euler Elastica
Presenter: Almut Burchard, University of Virginia
Date: Tuesday, March 19, 2002, Time: 4:30 p.m., Location: Jadwin A06
Abstract: We consider the dynamics for a thin, closed loop inextensible Euler's elastica moving in three dimensions. The equations of motion for the elastica include a wave equation involving fourth order spatial derivatives, and a second order elliptic equation for its tension. Local existence and uniqueness of solutions are established for sufficiently regular initial data. This is joint work with L.E. Thomas.
Joint Princeton University/IAS/Rutgers Non-Linear Analysis Seminar
Topic: Interaction functionals for hyperbolic systems of conservation laws
Presenter: Alberto Bressan, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Italy
Date: Thursday, March 21, 2002, Time: 4:00, Location: Fine Hall 214
Abstract: For strictly hyperbolic systems of conservation laws in one space dimension, global existence of entropy weak solution was proved in a classical paper of Glimm (1965). The construction of solution is here based on a compactness argument, where the total oscillation (i.e. the BV norm) is controlled by a suitable interaction functional. Very recently, wave interaction functionals have been introduced also in connection with viscous perturbations of hyperbolic systems, not necessarily in conservation form. This allows the construction of unique "viscosity solutions" to nonlinear hyperbolic systems, continuously depending on the initial data. The talk will also discuss the possibility of a-priori BV bounds (in terms of similar interaction functionals) for other types of approximations, such as relaxations or finite-difference numerical schemes.
March 25 - 29
Analysis Seminar
Topic: TBA
Presenter: Andreas Seeger, University of Wisconsin
Date: Monday, March 25, 2002, Time: 4:00 p.m., Location: Fine Hall 314
PACM Colloquium
Topic: Flash & Turn: Self-organization and dynamics of fireflies and ants
Presenter: Bard Ermentrout, University of Pittsburgh
Date: Monday, March 25, 2002, Time: 4:00 p.m., Location: Fine Hall 214
Algebraic Geometry Seminar
Topic: TBA
Presenter: Kiran Kedlaya, University of California, Berkeley
Date: Tuesday, March 26, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Discrete Mathematics Seminar
Topic: A trace bound for the discrepancy
Presenter: Bernard Chazelle, Princeton University
Date: Thursday, March 28, 2002, Time: 2:00 p.m., Location: Fine Hall 224
Princeton University/IAS Number Theory Seminar *** Please note special time
Topic: Ramified Triple Product Identities
Presenter: Thomas Watson, UCLA
Date: Thursday, March 28, 2002, Time: 4:00 p.m., Location: Fine Hall 322
Geometric Analysis Seminar
Topic: TBA
Presenter: Bruce Kleiner, University of Michigan & Courant Institute of Mathematics
Date: Friday, March 29, 2002, Time: 3:00 p.m., Location: Fine Hall 314
April 1-5
PACM Colloquium
Topic: Some themes of feedback control theory, and their relevance to systems molecular biology
Presenter: Eduardo Sontag, Rutgers University and Princeton University
Date: Monday, April 1, 2002, Time: 4:00 p.m., Location: Fine Hall 214
Algebraic Geometry Seminar
Topic: p-adic Fourier Theory and Lubin-Tate theory
Presenter: Jeremy Teitelbaum, University Illinois at Chicago.
Date: Tuesday, April 2, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: In this talk I will discuss some new results (joint with Peter Schneider) on p-adic integration that generalize old results of Amice and Lazard. Let $L$ be a finite extension of Qp$. We study the space of locally L-analytic functions on the ring of integers $o=o_L$, and its dual, the ring of locally $L$-analytic distributions. We show that this ring of distributions is isomorphic to the global functions on a rigid space $\hat{o}$ parameterizing $L$-analytic characters of $o$. The space $\hat{o}$ turns out to be quite interesting; if $L$ is not Q_p $\hat{o}$ isomorphic over C_{p}$ to the open unit disk, but is not a disk over any discretely valued extension of $L$. Our methods rely on Lubin-Tate theory and some results from Tate's classic paper on p-divisible groups. I will also explain how these results allow one to construct a p-adic L-function for a CM elliptic curve at a supersingular prime. Such functions have been discussed by Katz and by Boxall, but our results allow one to approach the construction using "Coleman power series" in a manner that is formally identical to that used for ordinary primes as described, for example, in deShalit's book.
Mathematical Physics Seminar
Topic: Tunneling on Quantum Graphs
Presenter: Pavel Exner, Theor. Physics, Czech Academy of Science, Prague
Date: Tuesday, April 2, 2002, Time: 4:30 p.m., Location: Jadwin A06
Department Colloquium
Topic: Evolution of Language
Presenter: Stephen Smale, University of California at Berkeley
Date: Wednesday, April 3, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Abstract: A mathematical model is presented which helps to understand how languages are formed. A theorem in this setting is the convergence to a common language under a hypothesis on linguistic encounters.
April 8 - 12
Analysis Seminar
Topic: TBA
Presenter: Diego Cordoba, Princeton University
Date: Monday, April 8, 2002, Time: 4:00 p.m., Location: Fine Hall 314
Algebraic Geometry Seminar
Topic: TBA
Presenter: Joseph Silverman, Brown University
Date: Tuesday, April 9, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Department Colloquium
Topic: TBA
Presenter: Michael Rabin, Harvard University
Date: Wednesday, April 10, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Joint Princeton University/IAS/Rutgers Non-Linear Analysis Seminar
Topic: $L_p$-bounds on curvature and rectifiability of singular setsy
Presenter: Jeff Cheeger, Courant Instititue, NYU
Date: Thursday, April 11, 2002, Time: 4:00, Location: Fine Hall 214
Princeton University/IAS Number Theory Seminar
Topic: Galois groups and geometry of modular varieties
Presenter: Alexander Goncharov, Brown University
Date: Thursday, April 11, 2002, Time: 4:30, Location: TBA
Geometric Analysis Seminar
Topic: TBA
Presenter: Rina Rotman, University of Toronto and the Courant Institute of Mathematics
Date: Friday, April 12, 2002, Time: 3:00 p.m., Location: Fine Hall 314
April 15 - 19
PACM Colloquium
Topic: TBA
Presenter: Christodolous Floudas, Chemical Engineering, Princeton University
Date: Monday, April 15, 2002, Time: 4:00 p.m., Location: Fine Hall 214
Algebraic Geometry Seminar
Topic: TBA
Presenter: Alexander Braverman, Harvard University
Date: Tuesday, April 16, 2002, Time: 4:30 p.m., Location: Fine Hall 314
Mathematical Physics Seminar *** Please note change in date from March 19, 2002
Topic: TBA
Presenter: Jakob Yngvason, University of Vienna
Date: Tuesday, April 16, 2002, Time: 4:30 p.m., Location: Jadwin A06
Geometric Analysis Seminar
Topic: Bifurcations of $J$-holmorphic maps
Presenter: Tom Parker, Michigan State University and the Institute for Advanced Study
Date: Friday, April 19, 2002, Time: 3:00 p.m., Location: Fine Hall 314
April 22 - 26
Analysis Seminar
Topic: The lost proof of Loewner's theorem
Presenter: Barry Simon, Caltech
Date: Monday, April 22, 2002, Time: 4:00 p.m., Location: Fine Hall 314
Abstract: A real-valued function, F, on an interval (a,b) is called matrix monotone if F(A) < F(B) whenever A and B are finite matrices of the same order with eigenvalues in (a,b) and A < B. In 1934, Loewner proved the remarkable theorem that F is matrix monotone if and only if F is real analytic with continuations to the upper and lower half planes so that Im F > 0 in the upper half plane. This deep theorem has evoked enormous interest over the years and a number of alternate proofs. There is a lovely 1954 proof that seems to have been "lost" in that the proof is not mentioned in various books and review article presentations of the subject, and I have found no references to the proof since 1960. The proof uses continued fractions. I'll provide background on the subject and then discuss the lost proof and a variant of that proof which I've found, which avoids the need for estimates, and proves a stronger theorem.
PACM Colloquium
Topic: TBA
Presenter: Ken Church, AT&T Labs - Research
Date: Monday, April 22, 2002, Time: 4:00 p.m., Location: Fine Hall 214
April 29 -May 3
PACM Colloquium
Topic: TBA
Presenter: Herb Keller, California Institute of Technology
Date: Monday, April 29, 2002, Time: 4:00 p.m., Location: Fine Hall 214
Princeton University/IAS Number Theory Seminar
Topic: TBA
Presenter: Brooks Roberts, University of Idaho
Date: Thursday, May 2, 2002, Time: 4:30, Location: TBA