Scientific Lectures

  • 23-Feb-07

Modelling biofilm growth in a porous medium with application in bioremediation

Studies on bioremediation in a porous medium have mainly focused on wastewater treatment. The interest in these investigations has focused on optimising degradation rates and substrate loading. Pore clogging has not been studied thoroughly. When p   more››

Simon Fraser University

  • 22-Feb-07

Complexity of Dependencies at the Syntactic Level and at the Discourse Level

Aravind K. Joshi is, at present, the Henry Salvatori Professor of Computer and Cognitive Science at the University of Pennsylvania. He served as the Director of the Institute for Research in Cognitive Science (IRCS) at the University of Pennsylvan   more››

Simon Fraser University

  • 21-Feb-07

Twisted K-theory (old and new), Part I

The Brauer group of a space and of a finite group. How are they related to K-theory?   more››

University of British Columbia

  • 19-Feb-07

The Reality of Computer Models: Statistics and Virtual Science

Computer models are imperfect representations of real phenomena. An austere view is that validating a model cannot be done, the "primary value of models is heuristic: models are representations, useful for guiding further study but not suscep   more››

University of Alberta

  • 16-Feb-07
  • 16-Feb-07

Homological Stability, Part II

Homological stability theorems have been proved for many families of groups like symmetric groups, linear groups, mapping class groups of surfaces and of 3-manifolds. I will review some examples and explain how such theorems are proved. As a more   more››

University of British Columbia

  • 16-Feb-07

Smooth Surfaces and Sharp Junctions

Because of their ability to form blends, respond to contact and produce both organic shapes as well as man made objects, implicit surfaces have the potential for uses other than the traditional clouds and water droplets. Models can be built with e   more››

University of British Columbia

  • 15-Feb-07

On Robust Utility Maximization

We study the problem of optimal investment in incomplete markets, robust with respect to stopping times. We work on a Brownian motion framework and the stopping times are adapted to the Brownian filtration. Robustness can only be achieved for loga   more››

University of British Columbia

  • 14-Feb-07

The lace expansion and the enumeration of self-avoiding walks

The lace expansion is an elegant combinatorial construction that provides a recursion relation for the number of self-avoiding walks. We first give an introduction to the lace expansion, and then explain how it has been used recently (in joint wor   more››

University of British Columbia

  • 14-Feb-07

Homological Stability, Part I

Homological stability theorems have been proved for many families of groups like symmetric groups, linear groups, mapping class groups of surfaces and of 3-manifolds. I will review some examples and explain how such theorems are proved. As a more   more››

University of British Columbia

  • 13-Feb-07

Leray-type regularizations of the Burgers and the isentropic Euler equations

We start from the Burgers equation vt + vvx = 0 and investigate a smoothing mechanism that replaces the convective velocity v in the nonlinear term by a smoother velocity field u. This type of regularization was first proposed in 1934 by Leray, wh   more››

University of British Columbia

  • 12-Feb-07

Essential dimension and algebraic stacks

The talk will be preceded by an organizational meeting. I will discuss recent work with Z. Reichstein and A. Vistoli on the subject of essential dimension.   more››

University of British Columbia

  • 12-Feb-07

Episodic Slow Slipping of Seafloor under Cascadia: What Physical Processes cause Aseismic Deformation Transients?

In several shallow-dipping subduction zones, including Cascadia, the seafloor undergoes episodes of more rapid than usual creep-slippage under the overlying margin, but at rates vastly slower than usual earthquake slip. In some locations, also inc   more››

University of British Columbia

  • 8-Feb-07

Culler-Shalen (semi-)norms

Let M be a 3-manifold with boundary consisting of one torus. I will show how Culler and Shalen defined a norm on the (real) Dehn-surgery space R2=H_1(partial M; R) associated to the canonical component of the character variety of M. I will then sh   more››

University of British Columbia

  • 8-Feb-07

Descriptive Complexity

Neil Immerman is one of the key developers of 'descriptive complexity', which he is currently applying to research in model checking, database theory, and computational complexity theory. Immerman is the winner, jointly with Róbert Szelepcsényi,   more››

University of British Columbia

  • 7-Feb-07

The term structure of interest rates

The interest rate r(t,t+x) between time t and time t+x is a smooth function of x, say ho_t(x). We consider ho_t as a stochastic process on (0,infty) into a suitable Hilbert space of curves, and we seek to define it as the solution of   more››

University of British Columbia

  • 7-Feb-07

Proof of Yuzvinsky's conjecture in the case of square matrices

Yuzvinsky's conjecture, posed in 1981, is concerned with a certain matrix coloring problem which arose from the classical studies of sums of squares. In this talk I will present a proof of the conjecture in the case of square matrices. The ideas o   more››

University of British Columbia

  • 1-Feb-07

Strong normality and modular normality

The notion of normality was intended to capture random behaviour in the digits of numbers, but some clearly patterned numbers pass the normality test; we propose a stronger test of normality that is passed by almost all numbers but failed by Champ   more››

University of British Columbia

  • 1-Feb-07

Quartic K3 surfaces without nontrivial automorphisms

We will deal with a gap in a result of Bjorn Poonen. He found explicit examples of hypersurfaces of degree d³3 and dimension n³1 over any field, such that the group of automorphisms over the algebraic closure is trivial, except for the pairs (n,   more››

University of British Columbia