Diff. Geom, Math. Phys., PDE Seminar: Yuzhao Wang

We will discuss the Cauchy problem for the cubic fourth order nonlinear Schrodinger equation (4NLS) on the circle. We first prove non-existence of solutions to (4NLS) for initial data lying strictly in negative Sobolev spaces, by using the short time Fourier restriction norm method. Then, we focus on the well-posedness issue of the renoramilzed 4NLS (so called the Wick ordered W4NLS). In particular, by performing normal form reductions infinite many times, we prove well-posedness of (W4NLS) in negative Sobolev spaces. This talk is based on a joint work with Tadahiro Oh (University of Edinburgh).