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SEPTEMBER 2006 |
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Differential Geometry and Geometric Analysis Seminar |
Topic: |
Volumes of balls in large Riemannian manifolds |
Presenter: |
Larry Guth, Stanford University |
Date: |
Friday, September 15, 2006, Time: 3:00 p.m., Location: Fine 314 |
Abstract: |
In the 80's, Gromov made several conjectures about the volumes of balls in Riemannian manifolds. The spirit of the conjectures is that if a Riemannian manifold is "large", then it should contain a unit ball whose volume is not too small. For example, if you take the standard metric on the n-sphere and increase it pointwise to form a new metric, then Gromov's conjecture implies that the new metric should contain a unit ball whose volume is bounded below by a constant c(n). I proved some of the conjectures, including this one. I will explain the conjectures and give some context, and then I will try to say something about the proof.
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Discrete Mathematics Seminar *** Please note special date, time and location |
Topic: |
Universally optimal distribution of points on spheres |
Presenter: |
Henry Cohn, Microsoft Research |
Date: |
Monday, September 18, 2006, Time: 3:00 p.m., Location: Fine 314 |
Abstract: |
http://www.math.princeton.edu/~bsudakov/cohn2006-fall.pdf |
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PACM Colloquium |
Topic: |
Soliton Lasers |
Presenter: |
J. Nathan Kutz, Applied Mathematics, University of Washington |
Date: |
Monday, September 18, 2006, Time: 4:00 p.m., Location: Fine 214 |
Abstract: |
A comprehensive treatment is given for the formation of mode-locked soliton pulses in optical fiber and solid state lasers. The pulse dynamics is dominated by the interaction of the cubic Kerr nonlinearity and chromatic dispersion with an intensity dependent perturbation provided by the mode-locking element in the laser cavity. The intensity dependent perturbation preferentially attenuates low intensity electromagnetic radiation which makes the mode-locked pulses attractors of the laser cavity. A review of the broad spectrum of mode-locked laser models, both qualitative and quantitative, are considered with the basic pulse formation phenomena highlighted. Although the numerous mode-locking models are considerably different, they are unified by the fact that stable solitons are exhibited in each case due to the intensity discrimination perturbation in the laser cavity. |
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Mathematical Physics Seminar |
Topic: |
Conformal invariance in the Ising model |
Presenter: |
Stanislav Smirnov, Univ. Geneva |
Date: |
Tuesday, September 19, 2006, Time: 4:30 p.m., Location: Jadwin 343 |
Abstract: |
We will discuss how to show that cluster interfaces in the Ising model (as well as its random cluster representation) have conformally invariant scaling limits, which can be identified with Schramm's SLE curves. The proof is based on the construction of covariant discrete holomorphic observables (fermions), and much of it can be generalized to other O(n) and random cluster models, with the appropriate values of the spin. |
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Operations Research and Financial Engineering Seminar |
Topic: |
Maximum drawdown, directional trading, and market crashes |
Presenter: |
Jan Vecer, Columbia University |
Date: |
Tuesday, September 19, 2006, Time: 4:30 p.m., Location: E-219, E-Quad |
Abstract: |
http://orfe.princeton.edu/papers/VecerAbstract.pdf |
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Discrete Mathematics Seminar |
Topic: |
Minimum codegree problems |
Presenter: |
Peter Keevash, Caltech |
Date: |
Wednesday, September 20, 2006, Time: 2:15 p.m., Location: Fine 224 |
Abstract: |
http://www.math.princeton.edu/~bsudakov/keevash2006-fall.pdf |
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Geometry, Representation Theory, and Moduli Seminar |
Topic: |
TBA |
Presenter: |
D. Arinkin, Caltech |
Date: |
Wednesday, September 20, 2006, Time: 3:00 p.m., Location: Fine 214 |
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Department Colloquium |
Topic: |
Towards conformal invariance of two-dimensional lattice models |
Presenter: |
Stanislav Smirnov, University of Geneva |
Date: |
Wednesday, September 20, 2006, Time: 4:30 p.m., Location: Fine 314 |
Abstract: |
See http://www.math.princeton.edu/~seminar/2006-07-sem/SmirnovAbstract9-20-2006.pdf |
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Ergodic Theory and Statistical Mechanics Seminar |
Topic: |
Asymptotical behavior of Frobenius numbers |
Presenter: |
Yakov Sinai, Princeton University |
Date: |
Thursday, September 21, 2006, Time: 2:00 p.m., Location: Fine 401 |
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Special Colloquium |
Topic: |
Transportation to random zeroes by the gradient flow |
Presenter: |
Misha Sodin, Tel Aviv University |
Date: |
Monday, September 25, 2006, Time: 3:00 p.m., Location: Fine 110 |
Abstract: |
Zeroes of the Gaussian entire function
\[
f(z) = \sum_{k=0}^\infty \xi_k \frac{z^k}{\sqrt{k!}}
\]
($\xi_0, \xi_1, \dots $ are Gaussian independent standard complex
random variables) have a remarkable and unique property: their distribution is invariant w.r.t. isometries of the plane. We show that the basins of zeroes under the gradient flow of the random potential $\displaystyle U(z) = \log|f(z)| - \frac{|z|^2}2$ partition the complex plane into domains of equal area.
We find three characteristic exponents $1$, $\frac85$, and $4$ of this random partition: the probability that the diameter of a particular basin is greater than $R$ is exponentially small in $R$; the probability that a given point $z$ lies on a distance larger than $R$ from the zero it is attracted to decays as $\exp \left( -R^{8/5} \right)$; and the probability that after throwing away $1\%$ of the area of the basin, its diameter is still larger than $R$ decays as $\exp \left( -R4 \right)$.
This is a joint work with Fedor Nazarov and Alexander Volberg. |
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PACM Colloquium |
Topic: |
Maximum Overhang |
Presenter: |
Peter Winkler, Mathematics, Dartmouth University |
Date: |
Monday, September 25, 2006, Time: 4:00 p.m., Location: Fine 214 |
Abstract: |
How far can a stack of n bricks hang over the edge of a table? It took 5 mathematicians (Mike Paterson, Yuval Peres, Mikkel Thorup, Uri Zwick and the speaker) to solve this classic problem---and the answer is not what most people thought. |
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Algebraic Geometry Seminar |
Topic: |
Hypertoric varieties |
Presenter: |
Nicholas Proudfoot, Columbia
University |
Date: |
Tuesday, September 26, 2006, Time: 4:30 p.m., Location: Fine 322 |
Abstract: |
A hypertoric variety is a quaternionic analogue of a toric variety. Just as the topology of toric varieties is closely related to the combinatorics of polytopes, the topology of hypertoric varieties interacts richly with the combinatorics of hyperplane arrangements and matroids. I will give an introduction to these spaces, and use arithmetic techniques to obtain combinatorial interpretations of the Betti numbers of hypertoric varieties, both for ordinary cohomology in the smooth case and intersection cohomology in the singular case. |
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Operations Research and Financial Engineering Seminar |
Topic: |
Generalised Deviations are Counterparts to Risk Measures |
Presenter: |
Stanislav Uryasev, University of Florida |
Date: |
Tuesday, September 26, 2006, Time: 4:30 p.m., Location: E-219, E-Quad |
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Discrete Mathematics Seminar |
Topic: |
On the minimal density of triangles in graphs |
Presenter: |
Alexander Razborov, IAS |
Date: |
Wednesday, September 27, 2006, Time: 2:15 p.m., Location: Fine 224 |
Abstract: |
http://www.math.princeton.edu/~bsudakov/razborov2006-fall.pdf |
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Geometry, Representation Theory, and Moduli Seminar |
Topic: |
TBA |
Presenter: |
A. Abanov, Stony Brook |
Date: |
Wednesday, September 27, 2006, Time: 3:00 p.m., Location: Fine 214 |
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Department Colloquium |
Topic: |
The Sato-Tate conjecture |
Presenter: |
Richard Taylor, Harvard University |
Date: |
Wednesday, September 27, 2006, Time: 4:30 p.m., Location: Fine 314 |
Abstract: |
A fixed elliptic curve over the rational numbers is known to have approximately p points modulo p for any prime number p. In about 1960 Sato and Tate gave a conjectural distribution for the error term. Laurent Clozel, Michael Harris, Nick Shepherd-Barron and I recently proved this conjecture in the case that the elliptic curve has somewhere multiplicative reduction. In this talk I will describe the Sato-Tate conjecture and the ideas Tate and Serre had for proving it. I will also sketch how we were able to prove sufficient higher dimensional modularity results to complete the proof. |
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OCTOBER 2006 |
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Algebraic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Dan Abramovich, Brown University |
Date: |
Tuesday, October 3, 2006, Time: 4:30 p.m., Location: Fine 322 |
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Discrete Mathematics Seminar |
Topic: |
Cycles in graphs |
Presenter: |
Jacques Verstraete, McGill University |
Date: |
Wednesday, October 4, 2006, Time: 2:15 p.m., Location: Fine 224 |
Abstract: |
http://www.math.princeton.edu/~bsudakov/verstraete2006-fall.pdf |
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Geometry, Representation Theory, and Moduli Seminar |
Topic: |
TBA |
Presenter: |
V. Alexeev, Georgia |
Date: |
Wednesday, October 4, 2006, Time: 3:00 p.m., Location: Fine 214 |
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Department Colloquium |
Topic: |
TBA |
Presenter: |
Luis Caffarelli, University of Texas at Austin |
Date: |
Wednesday, October 4, 2006, Time: 4:30 p.m., Location: Fine 314 |
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PACM Colloquium |
Topic: |
Vincent Van Gogh and Imitators in Greyscale: An Experiment in Cross-Disciplinary Stimulation |
Presenter: |
C. Richard Johnson, Jr., Electrical and Computer Engineering, Cornell University |
Date: |
Monday, October 9, 2006, Time: 4:00 p.m., Location: Fine 214 |
Abstract: |
This seminar describes a recently initiated project intended to accelerate the interaction of art historians and image processors in artist identification. The collection of digital images of artwork has been underway for over twenty years. Subsequently, in the last ten years image processors have initiated projects to process digitized images of paintings and drawings to assist art historians in artist identification. A key issue in the advance of this emerging technology, which is poised to expand rapidly over the next ten years, is bridging the gap between the two cultures of image processor system developers and art historian users. Four teams presently creating image processing schemes to assist the art historian in artist identification have agreed to prepare a daylong program for art historians to introduce them to the potential of this technology. The Van Gogh Museum in Amsterdam and the Kroller-Muller Museum in Otterloo have agreed to provide these four teams access to a common database of digitized paintings by Vincent Van Gogh and his imitators. The Van Gogh Museum plans to host a workshop on May 18, 2007, to be attended by art historians to whom the four teams will make presentations on brushstroke analysis in assistance of artist identification. The genesis of this pioneering experiment in cross-disciplinary stimulation raises a number of interesting issues about research between one field suffused with mathematics, models, and algorithms and another where such intellectual tools are practically absent and conceivably considered intellectually inappropriate. |
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Operations Research and Financial Engineering Seminar |
Topic: |
Tikhonov regularisation for functional minimum distance estimators |
Presenter: |
Olivier Scaillet, University of Geneva |
Date: |
Tuesday, October 10, 2006, Time: 4:30 p.m., Location: E-219, E-Quad |
Abstract: |
We study the asymptotic properties of a Tikhonov regularised (TiR) estimator of a functional parameter based on a minimum distance principle for nonparametric conditional moment restrictions. The estimator is computationally tractable and even takes a closed form in the linear case. We derive its asymptotic Mean Integrated Squared Error (MISE), its rate of convergence and its pointwise asymptotic normality under a regularisation para- meter depending on the sample size. The optimal value of the regularisation parameter is characterised. We illustrate our theoretical findings and the small sample properties with simulation results for two numerical examples. We also discuss two data driven selection procedures of the regularisation parameter via a spectral representation and a subsampling approximation of the MISE. Finally, we provide an empirical application to nonparametric estimation of an Engel curve. |
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Discrete Mathematics Seminar |
Topic: |
The rank of random graphs |
Presenter: |
Kevin Costello, Rutgers University |
Date: |
Wednesday, October 11, 2006, Time: 2:15 p.m., Location: Fine 224 |
Abstract: |
http://www.math.princeton.edu/~bsudakov/costello2006-fall.pdf |
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Geometry, Representation Theory, and Moduli Seminar |
Topic: |
TBA |
Presenter: |
I. Smith, Cambridge |
Date: |
Wednesday, October 11, 2006, Time: 3:00 p.m., Location: Fine 214 |
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Department Colloquium |
Topic: |
TBA |
Presenter: |
Klaus Schmidt, University of Vienna / Schrodinger Institute |
Date: |
Wednesday, October 11, 2006, Time: 4:30 p.m., Location: Fine 314 |
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PACM Colloquium |
Topic: |
One sketch for all: a sublinear approximation scheme for heavy hitters |
Presenter: |
Anna Gilbert, Mathematics, University of Michigan |
Date: |
Monday, October 16, 2006, Time: 4:00 p.m., Location: Fine 214 |
Abstract: |
The heavy hitters problem elicits a list of the m largest-magnitude components in a signal of length d. Although this problem is easy when the signal is presented explicitly, it becomes much more challenging in the setting of streaming data, where the signal is presented implicitly as a sequence of additive updates. One approach maintains a small sketch of the data that can be used to approximate the heavy hitters quickly. In previous work, this sketch is essentially a random linear projection of the data that fails with small probability for each signal. It is often desirable that the sketch succeed simultaneously for ALL signals from a given class, a requirement that may be called uniform heavy hitters. It arises, for example, when the signal is queried a large number of times or when the signal updates are stochastically dependent.
This talk describes a random linear sketch for uniform heavy hitters that succeeds with high probability. The recovery algorithm produces a list of heavy hitters that approximates the input signal with an l2 error that is optimal, except for an additive term that depends on the optimal l1 error and a controllable parameter e. The recovery algorithm requires space m*poly(log(d)/e) and time m2*poly(log(d)/e) to produce the list of heavy hitters. Up to logarithmic factors, the performance of this algorithm is the best possible with respect to several resources.
Joint work with Martin Strauss, Joel Tropp, and Roman Vershynin.
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Algebraic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Sándor Kovács, University of Washington |
Date: |
Tuesday, October 17, 2006, Time: 4:30 p.m., Location: Fine 322 |
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Operations Research and Financial Engineering Seminar |
Topic: |
TBA |
Presenter: |
Jonathan Eckstein, Rutgers University |
Date: |
Wednesday, October 18, 2006, Time: 4:30 p.m., Location: E-219, E-Quad |
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PACM Colloquium |
Topic: |
Solving Nasty Optimization Problems in Science and Engineering |
Presenter: |
Margaret Wright, Computer Science Department, CIMS, New York University |
Date: |
Monday, October 23, 2006, Time: 4:00 p.m., Location: E-Fine 214 |
Abstract: |
Many important optimization problems in science and engineering involve functions that can fairly be described as "nasty", which can mean any or all of wildly nonlinear, nonsmooth, noisy, and defined through complex black-box simulation or error-prone experimental data. Because it is often impossible or impractical to calculate derivatives of these functions, non-derivative methods are the only feasible choice. These methods are in the midst of a renaissance involving research on their theoretical and computational properties, as well as investigation of which methods are best suited for which applications. This talk will include examples of challenging problems along with the speaker's assessment of the state of the art in non-derivative optimization methods.
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Operations Research and Financial Engineering Seminar |
Topic: |
TBA |
Presenter: |
Robert Smith, University of Michigan |
Date: |
Tuesday, October 24, 2006, Time: 4:30 p.m., Location: E-219, E-Quad |
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NOVEMBER 2006 |
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PACM Colloquium |
Topic: |
Information Theory and Probability Estimation: From Shannon to Shakespeare via Laplace, Good, Turing, Hardy, Ramanujan, and Fisher |
Presenter: |
Alon Orlitsky, ECE and CSE, University of California, San Diego |
Date: |
Monday, November 6, 2006, Time: 4:00 p.m., Location: Fine 214 |
Abstract: |
Standard information-theoretic results show that data over small, typically binary, alphabets can be compressed to Shannon's entropy limit. Yet most practical sources, such as text, audio, or video, have essentially infinite support. Compressing such sources requires estimating probabilities of unlikely, even unseen, events, a problem considered by Laplace. Of existing estimators, an ingenious if cryptic one derived by Good and Turing while deciphering the Enigma code works best yet not optimally. Hardy and Ramanujan's celebrated results on the number of integer partitions yield an asymptotically optimal estimator that compresses arbitrary-alphabet data patterns to their entropy. The same approach generalizes Fisher's seminal work estimating the number of butterfly species and its extension authenticating a poem purportedly written by The Bard. The talk covers these topics and is self contained.
Joint work with Prasad Santhanam, Krishna Viswanathan, and Junan Zhang
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Algebraic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Aaron Bertram, University of Utah |
Date: |
Tuesday, November 7, 2006, Time: 4:30 p.m., Location: Fine 322 |
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Operations Research and Financial Engineering Seminar |
Topic: |
TBA |
Presenter: |
Dilip Madan, University of Maryland |
Date: |
Tuesday, November 7, 2006, Time: 4:30 p.m., Location: E-219, E-Quad |
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PACM Colloquium |
Topic: |
Denoising Color Images |
Presenter: |
Yang Wang, Mathematics, Georgia Institute of Technology |
Date: |
Monday, November 13, 2006, Time: 4:00 p.m., Location: Fine 214 |
Abstract: |
Natural color images captured by digital cameras often exhibit noticeable noise, particularly when the pictures are taken under low lighting or artificial lighting conditions. Traditional denoising techniques, which are often tested for removing artificial noise in monochromatic images, often do not work well for noisy color images.
In this talk, we present an overview of some of the traditional methods for denoising. We discuss a new strategy, which we call the cross-channel principle, that can be applied for very effective denoising of color images. In particular we show how this principle can be applied to the total variation denoising scheme and an ENO type denoising scheme.
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Algebraic Geometry Seminar |
Topic: |
Toric vector bundles and the resolution property |
Presenter: |
Sam Payne, Stanford University; Clay Institute |
Date: |
Tuesday, November 14, 2006, Time: 4:30 p.m., Location: Fine 322 |
Abstract: |
Is every coherent sheaf on an algebraic variety the quotient of a locally free sheaf of finite rank? I will discuss an investigation of this question via equivariant vector bundles on toric varieties, and will give examples of complete (singular, nonprojective) toric threefolds with no nontrivial equivariant vector bundles of rank less than or equal to 3. It is not known whether these varieties have any nontrivial vector bundles at all. |
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Department Colloquium |
Topic: |
TBA |
Presenter: |
Mircea Mustaţă, University of Michigan; IAS |
Date: |
Wednesday, November 15, 2006, Time: 4:30 p.m., Location: Fine 314 |
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Algebraic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Mircea Mustaţă, University of Michigan; IAS |
Date: |
Tuesday, November 21, 2006, Time: 4:30 p.m., Location: Fine 322 |
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PACM Colloquium |
Topic: |
TBA |
Presenter: |
Charles Epstein, Mathematics, University of Pennsylvania |
Date: |
Monday, November 27, 2006, Time: 4:00 p.m., Location: Fine 214 |
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Operations Research and Financial Engineering Seminar |
Topic: |
TBA |
Presenter: |
Marcel Rindisbacher, University of Toronto |
Date: |
Tuesday, November 28, 2006, Time: 4:30 p.m., Location: E-219, E-Quad |
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DECEMBER 2006 |
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PACM Colloquium - Distinguished Lecture Series |
Topic: |
TBA |
Presenter: |
Eric S. Lander, Broad Institute, Massachusetts Institute of Technology |
Date: |
Friday, December 1, 2006, Time: 8:00 p.m., Location:A02 McDonnell Hall |
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Algebraic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Günter Harder, Max Planck Institut für Mathematik; IAS |
Date: |
Tuesday, December 5, 2006, Time: 4:30 p.m., Location: Fine 322 |
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Operations Research and Financial Engineering Seminar |
Topic: |
TBA |
Presenter: |
Gordan Zitkovic, University of Texas |
Date: |
Tuesday, December 5, 2006, Time: 4:30 p.m., Location: E-219, E-Quad |
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Discrete Mathematics Seminar |
Topic: |
TBA |
Presenter: |
Tom Bohman, Carnegie Mellon University |
Date: |
Wednesday, December 6, 2006, Time: 2:15 p.m., Location: Fine 224 |
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Algebraic Geometry Seminar |
Topic: |
TBA |
Presenter: |
Brendan Hassett, Rice University |
Date: |
Tuesday, December 12, 2006, Time: 4:30 p.m., Location: Fine 322 |
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