The commutator of the Riesz transform (Hilbert transform in dimension 1) and a symbol $b$ is bounded on $L^2(\mathbb R^n)$ if and only if $b$ is in the BMO space BMO$(\mathbb R^n)$ (Coifman--Rochberg--Weiss). It is natural to ask whether it holds for commutator of Riesz transform on Heisenberg groups.
For a balanced bistable reaction-diffusion equation, an axisymmetric traveling front has been well known. We prove that an axially asymmetric traveling front with any positive speed does exist in a balanced bistable reaction-diffusion equation.
Prof Robert Coquereaux, Universite de Marseille, Luminy
4pm 21 March 2019
After introducing several geometrical models that can be used to calculate multiplicities in Lie group theory, we describe associated polytopes whose volumes can be considered as approximations of those multiplicities.
A brief introduction to stacks, bundle gerbes and their applications to T-dualities. Many examples will be presented so the talk should be accessible to anyone to some background in differential geometry and algebraic topology.