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Séminaire de EDP - Physique Mathématique

Probabilistic Local Well-posedness for the Schrodinger equation posed for the Grushin Laplacian

Mickael Latocca

Salle de Conférences

le 04 octobre 2022 à 11:00

"In this talk we study the local well-posedness of the equation itu+ΔGu=u2u i\partial_t u +\Delta_{G} u = |u|^{2}u where ΔG=x2+x2y2\Delta_G = \partial_x^2+x^2\partial_y^2 is the Grushin Laplacian and u(t):R2Cu(t):\mathbb{R}^2 \to \mathbb{C} is the solution, to be constructed with initial data u(0)=u0HGs(Rd)u(0)=u_0 \in H^s_G(\mathbb{R}^d) (the adapted Grushin-Sobolev spaces). From a deterministic perspective, the best local well-posedness theory is in C.([0,T),HG32+)\mathcal{C}^.([0,T),H^{\frac{3}{2}^{+}}_G) and the proof only uses the Sobolev embedding. Our main goal is to provide a probabilistic construction of local solutions for initial data u0HGsu_0 \in H_G^s where s<3/2s<3/2. This is achieved using linear and bilinear random estimates. In the first part of the talk I will introduce the random initial data which we will consider. Then I will explain why randomisation helps to lower the well-posedness threshold: this is a general argument in the study of dispersive equations with random initial data. Then I will explain how bilinear random estimates relate to our probabilistic well-posedness problem, which we will prove if time permits. We may also discuss some extensions of our result instead. This talk is based on a joint work with Louise Gassot. "