Seminar Coordinators
Seminars with home pages
Archived Seminars
Mathematics Department
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MARCH 2- MARCH 4, 2005 |
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| Discrete Mathematics Seminar | |
| Topic: | A tight threshold for metric Ramsey phenomena |
| Presenter: | Adriana Karagiozova, Princeton University |
| Date: | Wednesday, March 2, 2005, Time: 2:15 p.m., Location: Fine Hall 224 |
| Abstract: | Click here |
| Princeton University/Institute for Advanced Study Complex Geometry Seminar *** Note special date and location | |
| Topic: | An obstruction to constant scalar curvature Kahler metrics |
| Presenter: | Julius Ross, Columbia University |
| Date: | Wednesday, March 2, 2005, Time: 2:30 p.m., Location: West Building Lecture Hall, IAS |
| Abstract: | (Joint work with Richard Thomas) I will discuss K-stability and its relation to constant scalar curvature metrics. This leads to a notion of slope stability for manifolds in terms of its subschemes, which gives an obstruction to finding constant scalar curvature Kahler metrics in a given rational Kahler class. |
| Department Colloquium | |
| Topic: | Jacobian determinants and null Lagrangians |
| Presenter: | Tadeusz Iwaniec, Syracuse University |
| Date: | Wednesday, March 2, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Abstract: | Click here |
| Ergodic Theory and Statistical Mechanics Seminar | |
| Topic: | Mean Field Spin Glasses PART II: Random Multi Overlap Structures for Diluted Models and Optimization Problems |
| Presenter: | Luca De Sanctis, Princeton University |
| Date: | Thursday, March 3, 2005, Time: 2:00 p.m., Location: Fine Hall 322 |
| Abstract: | We introduce the Viana-Bray Model of Diluted Mean Field Spin Glass and show how to extend to this model some results, regarding the free energy, obtained for non-diluted systems and discussed in PART I. We also introduce the random p-XOR-SAT and K-SAT optimization problems and show that the methods we use extend to such problems as well. |
| Joint Analysis Seminar | |
| Topic: | Uniqueness properties of solutions of Schr\"{o}dinger equations |
| Presenter: | Alexandru Ionescu, University of Wisconsin - Madison |
| Date: | Thursday, March 3, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Abstract: | I will talk about some recent joint work with Carlos Kenig on a certain type of uniqueness property for solutions of nonlinear Schr\"{o}dinger equations on $R^d\times R$. |
| Topology Seminar *** CANCELLED *** | |
| Topic: | On knot Floer homology and satellite knots |
| Presenter: | Matthew Hedden, Columbia University |
| Date: | Thursday, March 3, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Abstract: | I will discuss the knot Floer homology invariants introduced by Ozsvath-Szabo and Rasmussen and what is known about these invariants for satellite knots. Part of this talk will address recent results calculating the Floer homology of Whitehead doubles of (2,2n+1) torus knots. These results are part of joint work with Philip Ording of Columbia University which aims to calculate the Floer homology of (1,1) satellite knots. |
| Geometric Analysis Seminar | |
| Topic: | Calibrated Manifolds and Gauge theory |
| Presenter: | Selman Akbulut, Michigan State University and the Institute for Advanced Study |
| Date: | Friday, March 4, 2005, Time: 3:00 p.m., Location: Fine Hall 314 |
| Abstract: | Calibrated geometries (introduced by Harvey and Lawson) give Interesting class of 3 and 4 dimensional submanifolds of 7 and 8 manifolds with exceptional holonomies G_2 and Spin(7). They are called associative and Cayley submanifolds. We will relate the deformation theory of these submanifolds to their gauge theories (recent joint work with Sema Salur), e.g. Seiberg-Witten equations appear as deformation equations of certain calibrated submanifolds. We will discuss how to associate invariants to G_2 manifolds from Seiberg-Witten for families. |
| Geometry, Representation Theory, and Moduli Seminar | |
| Topic: | On the cohomology of moduli spaces of pointed curves of low genus |
| Presenter: | Carel Faber, Johns Hopkins University |
| Date: | Friday, March 4, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Abstract: | The computation of the cohomology of moduli spaces of n-pointed curves may essentially be reduced, by using the action of the symmetric group, to that of the cohomology of local systems on M_g for the symplectic group. The answer for genus 1 has been known for a long time. Van der Geer and I have obtained explicit formulas for genus 2, which are partly conjectural. Bergstr\"om has obtained results for genus 3. Consani and I have obtained a new construction of the cohomology in genus 1 related to cusp forms. I will discuss these results. |
MARCH 7 - MARCH 11, 2005 |
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| PACM Colloquium | |
| Topic: | Progresses and Challenges in Multiscale Modeling |
| Presenter: | Weinan E, Applied Mathematics and Mathematics, Princeton University |
| Date: | Monday, March 7, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Abstract: | In the last several years, there has been tremendous growth of interest on multiscale modeling from many scientific and engineering disciplines. What are the issues involved? How much progress has been made? What are the challenges that we face in order to realize the full potential of multiscale modeling? This talk presents a personal view on these and related questions. We will begin with a quick discussion of the general issues in multiscale modeling. We then review some of the most successful multiscale methods, including the Car-Parrinello method and the quasicontinuum method for crystalline solids. In the second half of talk, we will focus on the problems from complex fluids and micro-fluidics. We end the talk with a canonical example in multiscale modeling, the contact line problem. |
| Group Actions and Automorphic Forms Seminar | |
| Topic: | On smooth classification of Z^k and R^k Cartan actions |
| Presenter: | Boris Kalinin, University of South Alabama |
| Date: | Tuesday, March 8, 2005, Time: 11:30 a.m., Location: Fine Hall PL |
| Abstract: | We consider actions of Z^k by hyperbolic diffeomorphisms of a compact manifold and R^k actions normally hyperbolic to the orbit foliation. Algebraic examples of such actions have been extensively studied recently. In contrast to Anosov diffeomorphisms and flows, the higher rank actions exhibit such remarkable properties as rigidity of invariant measures and rigidity of measure preserving isomorphisms. These algebraic actions are often locally rigid, i.e. smoothly conjugate to any small perturbation. We will discuss the problem of smooth classification of nonalgebraic actions, i.e. the existence of a smooth conjugacy to an algebraic model, and related rigidity questions. Our main result is a classification for certain classes of Cartan actions. |
| SPECIAL Analysis Seminar *** Please note special date, time, and location | |
| Topic: | The essential spectrum of advective equations |
| Presenter: | Roman Shvydkoy, University of Illinois at Chicago |
| Date: | Tuesday, March 8, 2005, Time: 2:00 p.m., Location: Fine Hall 214 |
| Abstract: | Early numerical simulations of certain 2D fluids revealed an important role of essential spectrum in formation of shortwave instabilities. For any linearized advective equation, such as the Euler equation, a general description of its essential spectrum can be given via the Sacker-Sell dynamical spectrum of an associated finite-dimensional system of ODEs. In this talk we discuss the relevant mathematical apparatus, and report on recent progress in finding the exact spectral pictures. |
| Joint Princeton University Institute for Advanced Study Number Theory Seminar *** Please note special time, date and location |
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| Topic: | Pretentious characters and the Polya-Vinogradov inequality |
| Presenter: | K. Sounadararajan, University of Michigan |
| Date: | Tuesday, March 8, 2005, Time: 3:00 p.m., Location: Fine Hall |
| Algebraic Geometry Seminar | |
| Topic: | Cohomology and Representations of Finite Group Schemes |
| Presenter: | Eric Friedlander, Northwestern University |
| Date: | Tuesday, March 8, 2005, Time: 4:30 p.m., Location: Fine Hall 322 |
| Abstract: | This is a report of joint work with Julia Pevtsova in which we provide a purely representation-theoretic construction of the scheme $Proj H^{ev}(G,k)$, where $G$ is a finite group scheme over a field $k$ of characteristic $p > 0$. Some applications are discussed. Before embarking upon a discussion of an arbitrary finite group scheme, we begin with $G$ the finite group $Z/p$ and then contemplate the much more difficult case of $Z/p \oplus Z/p$. |
| Operations Research and Financial Engineering Seminar | |
| Topic: | The Optimal Stopping of a Markov Chain, the Generalized Gittins Index, and Recursive Solution of Poisson and Bellman Equations |
| Presenter: | Isaac Sonin, University of North Carolina at Charlotte |
| Date: | Tuesday, March 8, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad |
| Abstract: | We discuss a modified version of the Elimination algorithm proposed earlier by the author to solve recursively a problem of optimal stopping of a Markov chain in discrete time and finite or countable state space. This algorithm and the idea behind it are applied to calculation of the classical and the generalized Gittins index and to solve the discrete versions of the Poisson and Bellman equations. |
| Discrete Mathematics Seminar | |
| Topic: | The exact Turán function of the generalized triangle |
| Presenter: | Oleg Pikhurko, Carnegie Mellon University |
| Date: | Wednesday, March 9, 2005, Time: 2:15 p.m., Location: Fine Hall 224 |
| Abstract: | Click here |
| Department Colloquium | |
| Topic: | The distribution of values of zeta and $L$-functions |
| Presenter: | Kannan Soundararajan, University of Michigan |
| Date: | Wednesday, March 9, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Ergodic Theory and Statistical Mechanics Seminar | |
| Topic: | Joinings of Cartan actions |
| Presenter: | Manfred Einsiedler, Princeton University |
| Date: | Thursday, March 10, 2005, Time: 2:00 p.m., Location: Fine Hall 322 |
| Abstract: | In joint work with E. Lindenstrauss we obtained a complete classifications of joinings of higher rank Cartan actions on locally homogeneous spaces. Unlike the case of torus actions, here there is no 'up to zero entropy part' in the classification -- every ergodic joining is algebraic. Previous results in that direction required additional assumptions. We will discuss the proof and a reformulation as an equidistribution - result. |
| Topology Seminar | |
| Topic: | Diophantine approximations on negatively curved manifolds |
| Presenter: | Sa'ar-David Hersonsky, Princeton University |
| Date: | Thursday, March 10, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Abstract: | Inspired by the theory of Diophantine approximation of a real (or complex) number by rational ones, we develop a theory of approximation of geodesic lines in a negatively curved Riemannian manifold. The talk will be a survey on some of our results: We prove a Dirichlet type theorem, define a Hurwitz type constant in terms of the lengths of closed geodesics, and a Khintchine-Sullivan type theorem on the Hausdorff measure of the geodesic lines starting from a cusp that are well approximated by cusp returning ones. This is a joint project with Frederic Paulin (ENS-Paris). |
MARCH 14 - MARCH 18, 2005 |
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| Group Actions and Automorphic Forms Seminar | |
| Topic: | TBA |
| Presenter: | Thomas Ward, University of East Anglia (UK) |
| Date: | Tuesday, March 15, 2005, Time: 11:30 a.m., Location: Fine Hall PL |
MARCH 21 - MARCH 25, 2005 |
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| PACM Colloquium | |
| Topic: | Finite frames and quantum detection |
| Presenter: | John Benedetto, University of Maryland |
| Date: | Monday, March 21, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Abstract: | We discuss quantum measurement in terms of positive operator-valued measures (POMs). For any tight frame with frame constant 1 for a separable Hilbert space there is an associated POM. Our setup is d-dimensional Hilbert space H and frames for H consisting of N elements. H represents a physical system, and it is known that the state x of the system is in E, a set of N given possible states. The problem is to perform a measurement in order to determine x. This is equivalent to constructing a POM on the subsets of E with a natural probabilistic property. Because of the relationship with frames, the problem reduces to constructing a tight frame with frame constant 1 which minimizes a probability of detection functional defined in terms of E. A compactness argument shows the existence of a solution. We solve the problem using techniques from Lagrangian mechanics and properties of SO(N) with the goal of constructing solutions numerically from the resulting equations. Geometrically uniform and Grassmannian frames are natural background material. This is a collaboration with Andrew Kebo. |
| Algebraic Geometry Seminar | |
| Topic: | Hodge type, divisibility of eigenvalues of Frobenius and slopes |
| Presenter: | H. Esnault, Essen |
| Date: | Tuesday, March 22, 2005, Time: 4:30 p.m., Location: Fine Hall 322 |
| Abstract: | We discuss Deligne's philosophy of the relation between Hodge filtration and congruences for points over finite fields. 1-st example: Lang-Manin conjecture: Fanos over finite field have points (via motivic cohomology) 2-st example: unequal characteristic: Hodge type vanishing in dim 2 over p-adic field implies points in the mod p-reduction. In higher dimension we have to replace the Hodge type condition by a coniveau condition. The theorem is based on Deligne's integrality theorem over a fintie field and its extesnion (jointly with him) over a local field. 3-rd example: slopes in rigid cohomology (joint with Berthelot-Bloch): 2 thetas divisors on an abelian variety over the finite field $\F_q$ have the same number of points mod q. The theorem relies on a theorem describing how to compute the slope $[0 \1[$ part of rigid cohomology. It has other applications, eg a vanishing theorem combining Serre's and Kodaira's vanihsing theorem in char. p. |
| Operations Research and Financial Engineering Seminar | |
| Topic: | Embracing statistical challenges in the information technology age |
| Presenter: | Bin Yu, University of California, Berkeley |
| Date: | Tuesday, March 22, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad |
| Abstract: | Information technology advances are making data collection possible in most if not all fields of science and engineering and beyond. Statistics as a scientific discipline is challenged and enriched by the new opportunities resulted from these high-dimensional data sets. In this talk, I will use serveral research projects to demonstrate how these IT challenges are met by finding new applications of traditional statistical thinking and methods and by incorporating compression and computation considerations into statistical estimation. In particluar, I will cover cloud detection over the polar region, microarray image compression for statistical analysis, and L2 boosting as a computationally efficient method for sparse nonparametric regression model fitting. |
| Discrete Mathematics Seminar | |
| Topic: | Odd independent transversals are odd |
| Presenter: | Tibor Szabo, ETH |
| Date: | Wednesday, March 23, 2005, Time: 2:15 p.m., Location: Fine Hall 224 |
| Abstract: | Click here |
| Department Colloquium | |
| Topic: | TBA |
| Presenter: | Dmitry Dolgopyat, University of Maryland |
| Date: | Wednesday, March 23, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Joint Analysis Seminar | |
| Topic: | TBA |
| Presenter: | Susan Friedlander, IAS and University of Illinois at Chicago |
| Date: | Thursday, March 24, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Topology Seminar | |
| Topic: | TBA |
| Presenter: | Walter Neumann, Institute for Advanced Study and Columbia University |
| Date: | Thursday, March 24, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
MARCH 28 - APRIL 1, 2005 |
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| PACM Colloquium | |
| Topic: | TBA |
| Presenter: | Nick Duffield, AT&T |
| Date: | Monday, March 28, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Group Actions and Automorphic Forms Seminar | |
| Topic: | TBA |
| Presenter: | Werner Müller, Bonn and the Institute for Advanced Study |
| Date: | Tuesday, March 29, 2005, Time: 11:30 a.m., Location: Fine Hall PL |
| Princeton University/Institute for Advanced Study Complex Geometry Seminar | |
| Topic: | Einstein metrics on Seifert fibered manifolds |
| Presenter: | János Kollár, Princeton University |
| Date: | Tuesday, March 29, 2005, Time: 2:30 p.m., Location: Fine Hall 110 |
| Algebraic Geometry Seminar | |
| Topic: | Arakelov inequalities and the uniformization of certain bounded symmetric domains |
| Presenter: | E. Viehweg, Essen |
| Date: | Tuesday, March 29, 2005, Time: 4:30 p.m., Location: Fine Hall 322 |
| Abstract: | Let $Y$ be a non-singular projective manifold with an ample canonical sheaf, and let $V$ be a rational variation of Hodge structures of weight one on $Y$ with Higgs bundle $E^{1,0}+E^{0,1}$. If $Y$ is a curve the Arakelov Inequality says that $\mu(E^{1,0})-\mu(E^{0,1})$ is smaller than or equal to the degree of the canonical sheaf. The equality implies that $V$ is the tensor product of a unitary bundle and the rank two variation of Hodge structures given by a theta characteristic; moreover $Y$ is the Shimura curve corresponding to $V$. We will discuss similar inequalities for surfaces $Y$. Here the equality will imply that $Y$ is either a compact Hilbert modular surface, or a ball quotient, and again $V$ is the tensor product of a canonical uniformizing variation of Hodge structures with a unitary bundle. Most of the results extend to variation of Hodge structures over quasi projective manifolds with a "nice" compactification and partly to the higher dimensional case. (joint work with Kang Zuo). |
| Operations Research and Financial Engineering Seminar | |
| Topic: | TBA |
| Presenter: | Kavita Ramanan, Carnegie Mellon University |
| Date: | Tuesday, March 29, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad |
| Discrete Mathematics Seminar | |
| Topic: | TBA |
| Presenter: | David Gamarnik, IBM Research |
| Date: | Wednesday, March 30, 2005, Time: 2:15 p.m., Location: Fine Hall 224 |
| Department Colloquium | |
| Topic: | TBA |
| Presenter: | Gregory Margulis, Yale University |
| Date: | Wednesday, March 30, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Topology Seminar | |
| Topic: | Deformations of the Khovanov Homology |
| Presenter: | Jacob Rasmussen, Princeton University |
| Date: | Thursday, March 31, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Abstract: | The Khovanov homology is a homological generalization of the Jones polynomial. The technique of deforming the definition of this theory was introduced by Lee and studied in the sl(n) case by Gornik. It has proven to be a very powerful one. In this talk I'll describe the space of possible deformations, and give some applications, both to computing the sl(n) theory and to better understanding its structure. |
| Geometry, Representation Theory, and Moduli Seminar | |
| Topic: | Positivity of Quasi-local Mass |
| Presenter: | Chiu-Chu Liu, Harvard University |
| Date: | Friday, April 1, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Abstract: | Quasi-local mass is a quantity associated to a spacelike 2-surface in a four dimensional spacetime. Several definitions of quasi-local mass have been proposed. I will discuss the positivity of one particular quasi-local mass based on joint works with Shing-Tung Yau. |
APRIL 4 - APRIL 8, 2005 |
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| PACM Colloquium | |
| Topic: | 33 Years of Bin Packing |
| Presenter: | David Johnson, AT&T |
| Date: | Monday, April 4, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Abstract: | In the bin packing problem, one is given a list of 1-dimensional items and asked to pack them into a minimum number of unit-capacity bins. This was one of the first NP-hard problems to be studied from the "approximation algorithm" point of view, and over the years it has served as a laboratory for the study of new questions about approximation algorithms and the development of new techniques for their analysis. In this talk I present a brief survey of this history, covering worst-case, average-case, and experimental results. The latter have led to many interesting conjectures and theorems, as well as the new "sum-of-squares" algorithm for the problem. |
| Group Actions and Automorphic Forms Seminar | |
| Topic: | TBA |
| Presenter: | Dave Witte Morris,University of Lethbridge |
| Date: | Tuesday, April 5, 2005, Time: 11:30 a.m., Location: Fine Hall PL |
| Operations Research and Financial Engineering Seminar | |
| Topic: | Useful Bounds on the Expected Maximum of Correlated Normal Variables |
| Presenter: | Andrew Ross, Lehigh University |
| Date: | Tuesday, April 5, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad |
| Abstract: | We compute useful upper and lower bounds on the expected maximum of up to a few hundred correlated Normal variables with arbitrary means and variances. Two types of bounding processes are used: perfectly dependent Normal variables, and independent Normal variables, both with arbitrary mean values. The expected maximum for the perfectly dependent variables can be evaluated in closed form; for the independent variables, a single numerical integration is required. Higher moments are also available. We use mathematical programming to find parameters for the processes, so they will give bounds on the expected maximum, rather than approximations of unknown accuracy. Our original application is to the maximum number of people on-line simultaneously during the day in an infinite-server queue with a time-varying arrival rate. The upper and lower bounds are tighter than previous bounds, and in many of our examples are within 5 percent of each other. |
| Discrete Mathematics Seminar | |
| Topic: | TBA |
| Presenter: | Igor Pak, MIT |
| Date: | Wednesday, April 6, 2005, Time: 2:15 p.m., Location: Fine Hall 224 |
| Topology Seminar | |
| Topic: | TBA |
| Presenter: | Jeff Brock, Brown University |
| Date: | Thursday, April 7, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Operations Research and Financial Engineering Seminar *** Please note special date, time, location | |
| Topic: | Columbia-Princeton Probability Day |
| Presenter: | List of prospective speakers include: Alain Bensoussan, University of Texas at Dallas Hans Föllmer, Humboldt University, Germany Albert N. Shiryaev, Steklov Mathematical Institute, Russian |
| Date: | Friday, April 8, 2005, Time: TBA, Location: TBA |
APRIL 11 - APRIL 15, 2005 |
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| PACM Colloquium | |
| Topic: | TBA |
| Presenter: | Pino Martin, Mechanical & Aerospace Engineering, Princeton University |
| Date: | Monday, April 11, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Operations Research and Financial Engineering Seminar | |
| Topic: | TBA |
| Presenter: | Albert N. Shiryaev, Steklov Mathematics Institute, Russia |
| Date: | Tuesday, April 12, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad |
| Department Colloquium | |
| Topic: | The Inverse Problem in Invariant Theory |
| Presenter: | Michael Larsen, Indiana University |
| Date: | Wednesday, April 13, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Abstract: | The direct problem in invariant theory is to describe the category of representations of a given group. Its inverse is to extract information about a group from information about its representations. The prototypical result in this direction is Tannaka duality. The ultimate goal is to recognize compact Lie groups which appear in nature, where in practice one typically does not know the category of representations up to isomorphism. |
| Joint Analysis Seminar | |
| Topic: | TBA |
| Presenter: | Vladimir Sverak, University of Minnesota |
| Date: | Thursday, April 14, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Topology Seminar | |
| Topic: | The Reduced Algebraic K-theory of Square-Zero Extensions by Free Modules |
| Presenter: | Ayelet Lindenstrauss, Indiana University |
| Date: | Thursday, April 14, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Abstract: | This talk is about joint work with Randy McCarthy (UIUC). We give a method for finding the completion at a prime p of the reduced (over A) K-theory of the square-zero extension of A by a free A-module of finite rank, $\tilde K(A \semiprod (A^{\oplus k}))^\wedge _p$. The calculation is carried out when $A$ satisfies a technical condition which (by work of Hesselholt and Madsen) is satisfied by perfect fields of characteristic $p$, and in that case generalizes the dual numbers ($k=1$) case which Hesselholt and Madsen calculate by different methods. Our calculation uses an invariant we call $W(A;M)$, which can be thought of as a Witt ring of $A$ with coefficients in $M$, or alternatively as cyclic homology of $A$ with coefficients in $M$. By Goodwillie calculus methods, $\tilde K (A \semiprod M) \simeq W(A;M\otimes S1)$, so what we actually study is $W(A; A^{\oplus k}\otimes S1)$. The completion at $p$ is needed for a topological analog of breaking the Witt ring down into a product of $p$-Witt vectors. |
APRIL 18 - APRIL 22, 2005 |
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| PACM Colloquium | |
| Topic: | TBA |
| Presenter: | David Cai, New York University |
| Date: | Monday, April 18, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Group Actions and Automorphic Forms Seminar | |
| Topic: | TBA |
| Presenter: | Alexander Gorodnik, Caltech |
| Date: | Tuesday, April 19, 2005, Time: 11:30 a.m., Location: Fine Hall PL |
| Algebraic Geometry Seminar | |
| Topic: | TBA |
| Presenter: | Gordon Heier, Harvard University |
| Date: | Tuesday, April 19, 2005, Time: 4:30 p.m., Location: Fine Hall 322 |
| Operations Research and Financial Engineering Seminar | |
| Topic: | TBA |
| Presenter: | Christian Menn, Cornell University |
| Date: | Tuesday, April 19, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad |
| Discrete Mathematics Seminar | |
| Topic: | Clique-width for graph classes defined by forbidden four-vertex subgraphs |
| Presenter: | Andreas Brandstaed, University of Rostock |
| Date: | Wednesday, April 20, 2005, Time: 2:15 p.m., Location: Fine Hall 224 |
| Abstract: | Click here |
| Department Colloquium | |
| Topic: | Probabilistic reasoning and Ramsey Theory |
| Presenter: | Benjamin Sudakov, Princeton University |
| Date: | Wednesday, April 20, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
| Abstract: | "Ramsey Theory" refers to a large body of deep results in mathematics concerning the partition of large collections. Its underlying philosophy is captured succinctly by the statement that "In a large system complete disorder is impossible". Since the publication of the seminal paper of Ramsey in 1930, this subject has grown with increasing vitality, and is currently among the most active areas in Combinatorics. An important factor in the development of Ramsey Theory was the successful application of the so-called "Probabilistic Method". This method was initiated more than fifty years ago by Paul Erdos, and became one of the most powerful and widely used tools in Discrete Mathematics. In this talk I will describe some classical results of Ramsey Theory together with recent progress on some old questions of Erdos which was made using probabilistic arguments. I will also discuss the problem of converting existence arguments into deterministic constructions, in particular, the recent explicit constructions of Bipartite Ramsey graphs. |
| Topology Seminar | |
| Topic: | TBA |
| Presenter: | Peter Kronheimer, Harvard University |
| Date: | Thursday, April 21, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
APRIL 25 - APRIL 29, 2005 |
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| PACM Colloquium | |
| Topic: | Discrete Denoising |
| Presenter: | Sergio Verdu, Applied Mathematics and Electrical Engineering, Princeton University |
| Date: | Monday, April 25, 2005, Time: 4:00 p.m., Location: Fine Hall 214 |
| Abstract: | Finite-alphabet signals corrupted by discrete noisy channels arise naturally in a wide range of applications spanning fields such as statistics, engineering, and computer science. Examples include DNA sequence analysis and processing, text correction, Hidden Markov model state estimation, and image denoising. While the field of filtering or denoising of continuous-alphabet signals has a long history, the field of discrete denoising has seen far less progress. In many discrete denoising applications, a good model for the randomness of the noisy channel is known, whereas the statistical description of the noiseless signal is either unknown or too complex. It is therefore of considerable interest to pose the problem of discrete universal denoising where no knowledge exists about the statistics of the noiseless signal while the channel statistics are assumed known. I will present the DUDE algorithm for discrete universal denoising which has linear complexity and attains universal optimality in a stochastic sense as well as a stronger semi-stochastic sense. I will also show several DUDE-based algorithms for channel decoding of systematically encoded redundant data. Joint work with E. Ordentlich, G. Seroussi, M. Weinberger and T. Weissman. |
| Operations Research and Financial Engineering Seminar | |
| Topic: | Stochastic Gradient Estimation |
| Presenter: | Michael Fu, University of Maryland |
| Date: | Tuesday, April 26, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad |
| Abstract: | We survey the methods of stochastic gradient estimation, including perturbation analysis, the likelihood ratio method, and weak derivatives. We illustrate the techniques using models in queueing, inventory, and finance. In the latter case, the methods can be used for estimating the so-called Greeks, which are crucial for hedging, and also for pricing American-style options (derivatives with early exercise opportunities). Computational examples using the estimators in stochastic approximation algorithms are described. |
| Topology Seminar | |
| Topic: | TBA |
| Presenter: | Helmut Hofer, NYU |
| Date: | Thursday, April 28, 2005, Time: 4:30 p.m., Location: Fine Hall 314 |
MAY 9 - MAY 14, 2005 |
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| Operations Research and Financial Engineering Seminar | |
| Topic: | TBA |
| Presenter: | Peter Bickel, University of California, Berkeley |
| Date: | Tuesday, May 10, 2005, Time: 4:30 p.m., Location: Room E-219, Engineering Quad |
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