Mon, 28 May 2007
17:00
17:00
L1
Gradient bounds are a very powerful tool to study heat kernel measures and
regularisation properties for the heat kernel. In the elliptic case, it is easy
to derive them from bounds on the Ricci tensor of the generator. In recent
years, many efforts have been made to extend these bounds to some simple
examples in the hypoelliptic situation. The simplest case is the Heisenberg
group. In this talk, we shall discuss some recent developments (due to H.Q. Li)
on this question, and give some elementary proofs of these bounds.