Past Events
Scientific, Seminar
Number Theory Seminar: Summing Pretentious Multiplicative Functions
November 26, 2009
University of British Columbia
I will present some new asymptotic formulas for the sums of complex-valued multiplicative functions whose values are near 1 on primes.
Scientific, Seminar
Number Theory Seminar: Counting arithmetic progressions in sums of squares
November 26, 2009
University of British Columbia
We show how the method of Green and Tao can be used to obtain the correct order of magnitude for the number of k-term arithmetic progressions in the integers representable as the sum of two squares, with a similar Roth-like theorem for subsets of...
Scientific, Seminar
Probability Seminar: Recurrence of the Simple Random Walk Path
November 25, 2009
University of British Columbia
A simple random walk (SRW) on a graph is a Markov chain whose state space is the vertex set and the next state distribution is uniform among the neighbors of the current state. A graph is called recurrent if a SRW on it returns to the starting vertex...
Scientific, Seminar
SCAIM Seminar: Consolidation of Unorganized Point Clouds for Surface Reconstruction
November 24, 2009
University of British Columbia
We consolidate an unorganized point cloud with noise, outliers, non-uniformities, and in particular interference between close-by surface sheets as a preprocess to surface generation, focusing on reliable normal estimation. Our algorithm includes two...
Scientific, Seminar
DG-MP-PDE Seminar: Non-negatively cross-curved transportation costs
November 24, 2009
University of British Columbia
The theory of optimal transport is concerned with phenomena arising when one matches two mass distributions in a most economic way, minimizing transportation cost of moving mass from one location to another. We consider an optimal transportation...
Scientific, Seminar
Algebraic Geometry Seminar: The local projective plane, a fractal-like curve, and Gamma_1(3)
November 23, 2009
University of British Columbia
I will report on joint work with E. Macri on the space of stability conditions for the derived category of the total space of the canonical bundle on the projective plane. It is a 3–dimensional manifold, with many chamber decompositions coming from...
Scientific, Seminar
Algebra Topology Seminar: Generalized Morse Theory for Maps to Two Dimensional Manifolds: PL-immersions of Polygons and Protein
November 18, 2009
University of British Columbia
Motivated by basic questions from robotics and molecular biology, we consider certain configuration spaces, and some associated maps to two dimensional Euclidian space. We are able to understand the singular sets for a natural subset of these maps...
Scientific, Seminar
Probability Seminar: Cluster expansions and fixed points
November 18, 2009
University of British Columbia
Cluster expansions give convergent expressions for measures on infinite dimensional spaces, such as those that occur in statistical mechanics. One approach to these convergence questions is via fixed points for infinite dimensional increasing...
Scientific, Seminar
General Hardy inequalities with improvements and applications
November 18, 2009
University of British Columbia
We derive a general Hardy inequality and show most Hardy inequalities can be seen as special cases of this inequality. In addition we characterize the improvements of this inequality and (time permitting) we show an application of this inequality to...
Scientific, Seminar
Bijective counting of one-face maps on surfaces
November 18, 2009
University of British Columbia
A one-face map is a graph embedded in a compact surface, in such a way that its complement is a topological disk. Dually, it can be viewed as a polygon of even size, in which edges have been pasted pairwise to create a surface. These objects have...