Pacific Institute for the Mathematical Sciences - PIMS

Regularity criteria for Navier-Stokes equations

In the talk I will first review various known regularity criteria and partial regularity theory for 3D incompressible Navier-Stokes equations. I will then talk about a joint work with Gustafson and Kang on regularity criteria based on scaled space   more››

University of British Columbia

Image and Video Special Effects based on Geometry and Partial Differential Equations

Simon Fraser University

Formal proofs in geometry

Traditional mathematical proofs are written in a way to make them easily understood by mathematicians. Routine logical steps are omitted. An enormous amount of context is assumed on the part of the reader. Proofs, especially in topology and geomet   more››

University of Calgary

Three-dimensional Turing patterns: Stability, implications in biological modeling, and equilibrium

Turing patterns are structures that can form spontaneously in systems of reacting and diffusing chemicals. Since the 1950s, when Alain Turing first put forth the theoretical considerations, there has been a vast amount of literature on the subject. I   more››

Simon Fraser University

Functional equations for Mahler measures of genus-one curves

The Mahler measure of an n -variable polynomial P is the integral of log | P | over the n -dimensional unit torus T n with the Haar measure. Consider a family of two-variable polynomials whose coefficients depend on one parameter. Then the Mahler mea   more››

University of British Columbia

Computer-assisted proofs in geometry

In recent years, computer-assisted proofs have become relatively common. For example, in 2002, W. Tucker published a proof of problem 14 (concerning strange attractors) on Smale's list of problems for the new century. Other recent computer-assiste   more››

University of Calgary

Semilinear elliptic systems with exponential nonlinearities in two dimensions

We study the existence of nontrivial solutions for the following system of two coupled semilinear Poisson equations: left{ begin{array}{rlllllll} -Delta u &=& g(v), & v & > & 0 & extrm{in} Ω, \ -Delta v &=&   more››

University of British Columbia

Exponential integrators

Numerical schemes for ordinary differential equations, using matrix exponentials, were introduced in the 1960's as a way to overcome the stability restrictions of explicit methods. However, such methods were not considered as a practical mean of s   more››

University of British Columbia

Sphere Packings and foams

Kepler's conjecture asserts that the densest possible arrangement of congruent balls in three dimensions is the familiar pyramid arrangement, which is used to stack oranges at the fruit stand. A 300-page proof of this theorem finally appeared in J   more››

University of Calgary

Ehrhart analogue of the h-polynomial

In this talk I will explain how the Ehrhart problem of counting lattice points in a polyhedron is equivalent to a problem in orbifold cohomology. This equivalence can be used to prove a conjecture of Stanley that relates the Ehrhart generating pol   more››

University of British Columbia

Perturbations Methods in Default Modeling

Stochastic volatility has played a central role in modeling equity derivative markets. In the recent years the market in credit-linked derivative products has grown tremendously and had generated a need for more sophisticated models of default. We   more››

University of British Columbia

The integral geometry of random sets

In various scientific fields from astro- and high energy physics to neuroimaging, researchers observe entire images or functions rather than single observations. The integral geometric properties, notably the Euler characteristic of the level/excu   more››

University of Calgary

Primitivity in twisted homogeneous coordinate rings

Given a projective k-scheme X, an automorphism sigma of X and an invertible sheaf L on X, one can form the twisted homogeneous coordinate ring bigoplus_{nge 0} H0(X,L_n), where L_n=Lotimes L^{sigma}otimes cdotsotimes L^{sigma^{n-1}. We study the q   more››

University of British Columbia

Comparing sumsets and difference sets

Since addition is commutative but subtraction is not, the subset S+S of a finite set S is predisposed to be smaller than the difference set S-S. As Mel Nathanson wrote: Even though there exist sets S that have more sums than differen   more››

University of British Columbia

A Mirror Theorem for Complete Intersection Orbifolds in Weighted Projective Spaces

The famous mirror formula for quintic threefolds, conjectured to Candelas, de la Ossa, Green, and Parkes, provides detail information on genus zero Gromov-Witten invariants of the quintic threefold. Mirror formula has been extended to larger class   more››

University of British Columbia

Prediction of dispersal and establishment of aquatic nonindigenous species across Ontario lakes: Linking vector-based and habita

Prediction of range expansion of nonindigenous species is important, as it is often easier to prevent invasions than to mitigate impacts once invasions have occurred. A combination of models for propagule pressure (gravity models) and habitat matc   more››

University of Alberta

Closed form solution for maximizing CRRA type utility

This paper studies the problem of optimal investment in incomplete markets when the agents have CRRA type utility. Closed form solutions are obtained up to some unhedgeble risk represented by a process orthogonal on the stock price. The   more››

University of British Columbia

On classifications of links up to C_n-moves

A C_n-move (nin{Bbb N}) is a local move on links defined by Habiro, which can be regarded as a 'higher order crossing change'. The C_n-equivalence is an equivalence relation on links generated by C_n-move. The C_m-equivalence implies the C_n-equiv   more››

University of British Columbia

Arthur Sherman (Laboratory of Biological Modeling, NIDDK/NIH)

University of British Columbia

Nucleation of localised pattern in continuous media

The formation of patterns from quiescence under the continuous variation of a parameter has long been of interest across the physical and life sciences since the pioneering work of Alan Turing. We describe how spatially localised patches of patter   more››

University of British Columbia