Simon Fraser University

Solvers for the Boolean satisfiability problem have been increasingly used to solve hard problems from many fields and now routinely solve problems with millions of variables. Combinatorial problems are a natural target, as SAT solvers contain...

We explore graphs of high cop number. We give new lower bounds for cop number of graphs of high girth. We also present a new class of undirected graphs with cop number $(1-o(1)) \sqrt{n/2}$ and a class of directed graphs with cop number $(1-o(1))...

A theme that cuts across many domains of computer science and mathematics is to find simple representations of complex mathematical objects such as graphs, functions, or distributions on data. These representations need to capture how the object...

We consider an aggregation model that consists of an active transport equation for the macroscopic population density, where the velocity has a nonlocal functional dependence on the density, modelled via an interaction potential. We set up the model...

Peritrichously flagellated bacteria such as E. coli swim in a fluid environment by rotating motors embedded in the cell membrane and consequently rotating multiple helical flagella. We present a mathematical model of a microswimmer that can freely...

The PPSZ algorithm, due to Paturi, Pudlak, Saks and Zane, is currently the fastest known algorithm for the k-SAT problem, for every k>3. For 3-SAT, a tiny improvement over PPSZ was obtained by Hertli. We introduce a biased version of the PPSZ...

Could an asteroid that explodes over the ocean generate a tsunami threatening coastal populations far away? We show simulations of tsunami propagation from asteroid-generated airbursts. We then present a 1D model with an explicit solution to better...

In this talk I will introduce a new semi-algebraic proof system, called Stabbing Planes that is in the style of DPLL-based modern SAT solvers. Stabbing Planes proofs extend the DPLL branching from single variables to branching on arbitrary linear...

How does representation of a problem affect the complexity of solving it? What is the interplay between the richness of a domain in which a statement is expressed and the complexity of proving that statement? Not only this is a fundamental question...

We will disucss some recent advances in the convergence of Anderson acceleration, an extrapolation technique that can be applied to general fixed-point iterations. The theory will be illustrated on some examples of systems arising from finite element...