Scientific General Events
The Mahler measure of curves and surfaces
by Marie José Bertin Université Pierre et Marie Curie (Paris 6), Institut de Mathématiques de Jussieu
I report on some new examples of explicit logarithmic Mahler measures of multivariate polynomials.
When the polynomial defines a parametrizable curve, its Mahler measure is expressed in terms of Bloch-Wigner dilogarithms of an element of the Bloch group of an imaginary quadratic field ( Thus a link with hyperbolic varieties). When the polynomial defines a singular K3-surface, I give several examples of the Mahler measure expressed in terms of the L-series of the K3-surface for s=3. Dedekind zeta motives for totally real fields by Francis Brown CNRS, Institut de Mathématiques de Jussieu, IHES
On singular Bott-Chern classes
by José Ignacio Burgos Gil Universidad de Barcelona
The singular Bott-Chern classes measure the failure of an exact Riemann-Roch theorem for closed immersions at the level of currents. They are the key ingredient in the definition of direct images of hermitian vector bundles under closed immersions and in the proof of the arithmetic Riemann-Roch theorem in Arakelov geometry for closed immersions. There are two definitions of singular Bott-Chern classes. The first due to Bismut, Gillet and Soulé uses the formalism of super connections. The second, due to Zha, is an adaptation of the original definition of Bott-Chern classes by Bott and Chern.In this talk we will give an axiomatic characterization of singular Bott-Chern classes, which is similar to the characterization of Bott-Chern forms, but that depends on the choice of an arbitrary characteristic class. This characterization allow us to give a new definition of singular Bott-Chern forms by means of the deformation to the normal cone technique and to compare the previous definitions of singular Bott-Chern forms. Moreover we will give an explicit computation of the characteristic class associated to Bismut-Gillet-Soulé definition of singular Bott Chern currents.
Generic p-rank of semi-stable fibration
by Junmyeong Jang Purdue University
In this presentation, I will be concerned with two pathological phenomenons of positive characteristic, the failure of Miyaoka-yau inequality and the failure of semi-positivity theorem. Szpiro showed that a Frobenius base change of non-isotrivial smooth fibration violates Miyaoka-Yau inequality. For such a fibration, if the p-rank of the generic fiber is maximal, the dimension of the Lie algebra of Picard scheme is stable after the Frobenius base change. Using this fact and a reduction argument we can construct a counter example of Miyaoka-Yau inequality with smooth Picard scheme, which is a counterexample of Parshin's expectation. And we will see for a semi-stable fibration p : X ? C of a proper smooth surface to a proper smooth curve, if the p-rank of the generic fiber is maximal, the semi-positivity theorem holds and if the p-rank of the generic fiber is 0, some Frobenius base change of p violates the semi-positivity theorem. This result may be applied to a problem of the distribution of p-ranks of reductions of a certain non-closed point in the moduli space of curves over Q¯.
The Abel-Jacobi map on the Einsestein symbol
by Matthew Kerr Durham University
In this talk we consider two different constructions of motivic cohomology classes on families of toric hypersurfaces and on Kuga varieties. Under certain modularity conditions on the former we say how the constructions "coincide", obtaining a complete explanation of the phenomenon observed by Villegas, Stienstra, and Bertin in the context of Mahler measure. (This is where the AJ computation on the Kuga varieties, done using our formula with J. Lewis and S. Mueller-Stach, will be summarized). We also look at an application of the toric construction in the non-modular case, to limits of normal functions for families of Calabi-Yau 3-folds.
Moduli of polarized logarithmic Hodge structures and period maps
by Sampei Usui Osaka University
Height and GIT weight
by Xiaowei Wang The Chinese University of Hong Kong
In this talk, we will establish a new connection between the weight in the geometric invariant theory and the height introduced by Cornalba and Harris CH and Zhang Z. Then I will explains two applications of this connection.
Talks will be held at CAB 269 (April 12, 14, 15, 16) and ETL E1 008 (April 13). We have booked the computer lab at CAB 341. map
This workshop will bring together scientists working on mathematical modeling of viral disease with a focus on viral evolution and epidemiology, and with particular application to influenza and HIV.
Please note: People registering after March 25th will not be registered for the dinner on Friday, April 4th. Please inquire at the meeting about the availability of space at the dinner, if you wish to attend.
Waves, Vortices, and Climate Modelling
Welcome to the 2008 Applied Mathematics Graduate Student Conference (AMGSC) webpage. The conference was held on Saturday, January 26 and Sunday, January 27 at Simon Fraser University. Some students gave short presentations based on past course project or current research.
Speaker: Derek Bingham
Title: Statistical Research in a Collaborative Environment
Modern statistical research is often motivated by applied problems that arise in other areas of science. Finding solutions to these applied problems leads to collaborations between statisticians and subject-specific researchers. Working in such a collaborative environment brings much benefit to both parties, but is not without challenges. This talk will relate some of my experiences working in such an environment, and how one might build successful long-term collaborative relationships.
Title: Confidence intervals for proportions and quantiles with application to NHANES
Speaker: Cindy Feng
It has been noted that the usual confidence interval for proportions does not perform well for large and small values of p. In surveys the issue is complicated by the survey design and issues of whether to use design effects, effective sample size and effective degrees of freedom arise. The question is which of the many possible confidence intervals available should be recommended for the U.S. National Health and Nutrition Examination Surveys (NHANES) end users and what cautions should be given. In addition, the issues may be different if the interval is actually being used in combination with Woodruff’s method to form confidence intervals for small and large quantiles.
Title: Median Loss Analysis
Speaker: Pen Yu
In classical decision theory in statistics, Wald (1950) first introduced the risk function, and used it to evaluate how good the estimators are. Conventionally, the risk is assumed to be finite in most situations. In other words, we cannot handle the problems of heavy-tail distributions like the Cauchy distribution. In this talk, I will introduce the median version of the risk, called the median loss, and compare it with the risk and other domination criteria. Moreover, we will see that the estimator by the median loss approach is more loss robustness than the estimator by the risk, such as the Bayes estimator.
Title: Statistical Monitoring of Clinical Trials with Multivariate Response or Multiple Arms Using Repeated Confidence Bands
Speaker: Lihui Zhao
X. Joan Hu (Simon Fraser University) Stephen W. Lagakos (Harvard University)
Clinical trials with multivariate response or multiple arms have become increasingly common because of their potential efficiency and cost saving. Interim analyses of such studies are often guided by parametric assumptions for the underlying probability models. There are situations where it is not clear at the outset how the responses differ among the treatment groups and what kinds of differences are clinically meaningful. More flexible designs and monitoring procedures are therefore desirable. In this talk, we extend the repeated confidence bands approach (Hu and Lagakos, 1999) to studies with multivariate target function. We use a recent AIDS clinical trial to illustrate how to apply the multivariate repeated confidence bands (MRCB) approach in practice.
Title: Prior Sensitivity and Cross-Validation using Sequential Monte Carlo
Speaker: Luke Bornn
In a Bayesian setting, adequately approximating the model of interest can be computationally expensive in the order of hours or even days. Prior sensitivity and cross-validation are both tasks that involve repeating this approximation repeatedly, potentially hundreds or thousands of times. In this talk I will demonstrate how sequential Monte Carlo methods can make prior sensitivity and cross-validation feasible in situations where the distribution of interest is not available analytically, reducing computational time by an order of magnitude or more in most settings.
Title: The Publication Process in Statistics
Speaker: Paul Gustafson
Peer-reviewed academic journals are central to scientific life. Scientists of all stripes spend substantial proportions of their time reading, writing, and reviewing for journals. Based on my experiences as an author, a reviewer, an associate editor, and an editor, I will make some comments on how academic journals function, and try to offer some advice on navigating the publication process.
Title: Finding approximate solutions to combinatorial problems with very large datasets using BIRCH
Speaker: Justin Harrington
Over time the boundaries between Computer Science and Statistics have blurred, with a number of disciplines (e.g. Machine Learning) being actively researched in both schools. One such technique is called BIRCH (Balanced Iterative Reducing and Clustering using Hierarchies) (Zhang et al, 1997), which is a data pre-processing tool used for clustering extremely large datasets with a k-means algorithm. The advantage of this algorithm is that it generates "sufficient statistics" with only one pass of the dataset, and these values can then be used instead of the whole dataset for certain applications.
In this talk we demonstrate this algorithm's application in two fields, namely robust statistics and (if time permits) a new clustering method called Linear Grouping Analysis (Van Aeslt et al, 2006).
Title: Designs for Computer Experiments
Speaker: Chunfang Lin
Latin hypercube designs have been widely adopted in conducting computer experiments. In this talk, we introduce methods for constructing a rich class of Latin hypercube designs with appealing projection and space-filling properties. The class includes many orthogonal Latin hypercube designs that are not available in the literature, as well as nearly-orthogonal Latin hypercubes and two-level orthogonal-array based orthogonal Latin hypercube designs. This is joint work with Randy R. Sitter.
The 29th Annual Alberta Statisticians Meeting is sponsored by the Department of Mathematics and
Statistics and the Faculty of Science at the University of Calgary, and also by PIMS.
This meeting serves many purposes. It allows faculty and graduate students working in probability and statistics
at different universities in Alberta to interact, make contacts, and discuss their research. It serves as a training
vehicle for highly qualified people (HQP) working in probability and statistics. It affords statisticians working in
the private and non-academic public sector to discuss their problems with academic researchers. In addition,
it affords graduate students an opportunity to present their work and themselves to possible future employers.
Registration will be at the door.
For further information, please contact David Scollnik at email@example.com.
The Cycle Double Cover Conjecture (CDC) was proposed independently by
P.D. Seymour (1979) and G. Szekeres (1973). The conjecture is easy to state:
"For finite every 2-connected graph, there is a list of cycles (polygons)
such that every edge of the graph is an edge of exactly two cycles
in the list."
As an example, if the graph is embedded in a surface (without crossing
edges) in such a way that all faces are bounded by cycles,
then the boundary cycles of the faces will "double cover" the edges.
Although the statement of the conjecture is very simple, the solution
has eluded dozens of attacks over 30 years.
This conjecture (and its numerous variants) is considered by most graph
theorists to be one of the major open questions in the field.
One reason for this is the close connections that this problem has
with topological graph theory, the theory of Nowhere-zero flows,
graph colouring and polyhedral combinatorics. MathSciNet lists more
25 articles with "cycle double cover" (or "double cycle cover") in
The workshop will include some formal presentations
with the purpose of bringing the participants up to date on
techniques and recent results. Long collaborative working periods will
take the majority of the working time.
The 19th Annual Canadian Conference on Computational Geometry (CCCG 2007) will
be held in Ottawa, Canada on August 20-22, 2007 at Carleton University, with a
welcome reception on the evening of August 19th.
CCCG focuses on the computational aspects of geometric problems. Computational
Geometry applies to all fields that touch geometric computing. Application
areas are as diverse as computer graphics and animation, computer vision,
CAD/CAM, GIS, pattern recognition, wireless communication, robotics, urban
planning, graph drawing, or statistical analysis to name just a few.
CCCG is intended to be a forum, accessible to a broad variety of researchers in
the area, to disseminate and discuss new results. All submitted papers will be
refereed, but we have no maximum target on the number of submissions that are
accepted. All papers that present new, original, and error free results that
are of interest to the greater computational geometry community will be
accepted. The intended audience for this conference includes graduate and
undergraduate students, researchers in the area and members of industry that
work in areas requiring the use of intensive geometric computation.
The International Conference of Theoretical and Numerical Fluid Mechanics
III is being held in honor of Professors Giovanni Paolo Galdi and Rolf
Rannacher, in celebration of their sixtieth birthdays. Reflecting their
interests, it will be an interdisciplinary meeting within the general field
of mathematical and computational fluid dynamics, devoted mainly to
Newtonian and non-Newtonian viscous flow. While promoting a high quality of
mathematical treatment, no area of practical application will be excluded
due to the present intractability of interesting mathematical difficulties.
Thus, there will be lectures on turbulence, blood flow, sedimentation,
fluid structure interaction, flow control, and the dynamical systems
perspective, as well as key issues of the Navier-Stokes theory.
Short courses will be offered by Professors Galdi and Rannacher on the two
days preceding the conference. Professor Rannacher will lecture on
“Numerical methods for the simulation of fluid-structure interaction”.
Professor Galdi will lecture on “Topics in the Mathematical Theory of
Registration is open to the general scientific and engineering community.
All registrants are invited to give poster presentations. Also, all
registrants along with their families are welcome and encouraged to join in
all of our sponsored social events. PIMS has provided special funds for
supporting the travel of graduate students to attend this meeting. Graduate
students wishing such support should apply for it by writing to John
Heywood at firstname.lastname@example.org .
CECM, Maplesoft, MITACS, IRMACS and PIMS are pleased to present "CECM 2007", a summer conference hosted by CECM under the title "Summer Workshop on Computational Mathematics" at Simon Fraser University.
The Workshop Program includes talks and a poster session which cover diverse topics in mathematics with an emphasis on computation.
Registration is required.
For more information, please visit: