Seminar

One critical difficulty in the study of geometric nonlinear wave equations, compared with the classical NLW, is that there are nontrivial interactions between unbalanced frequencies. This requires one to understand a class of linear paradifferential flows, which describe the evolution of high frequency waves on a low frequency background. This talk continues and completes the stuff in the August workshop lectures. A brief review of the workshop notes might be helpful in order to better place this talk in the broader context.