Weak-Type estimates for the metaplectic representation restricted to the shearing and Dilation subgroup of SL(2, ℝ)

We consider the subgroup G of SL(2, ℝ) consisting of shearing and dilations, and we study the decay at infinity of the matrix coefficients of the metaplectic representation restricted to G. We prove weak-type estimates for such coefficients, which are uniform for functions in the modulation space M 1 . This work represents a continuation of a project aiming at studying weak-type and Strichartz estimates for unitary representations of non-compact Lie groups

Pseudodifferential operators on LpL^p, Wiener amalgam and modulation spaces

We give a complete characterization of the continuity of pseudodifferential operators with symbols in modulation spaces $M^{p,q}$, acting on a given Lebesgue space $L^r$. Namely, we find the full range of triples $(p,q,r)$, for which such a boundedness occurs. More generally, we completely characterize the same problem for operators acting on Wiener amalgam space $W(L^r,L^s)$ and even on modulation spaces $M^{r,s}$. Finally the action of pseudodifferential operators with symbols in W(\Fur L^1,L^\infty) is also investigated.Comment: 27 page

Metaplectic representation on Wiener amalgam spaces and applications to the Schr\"odinger equation

We study the action of metaplectic operators on Wiener amalgam spaces, giving upper bounds for their norms. As an application, we obtain new fixed-time estimates in these spaces for Schr\"odinger equations with general quadratic Hamiltonians and Strichartz estimates for the Schr\"odinger equation with potentials $V(x)=\pm|x|^2$

Sharpness of some properties of Wiener amalgam and modulation spaces

We prove sharp estimates for the dilation operator $f(x)\longmapsto f(\lambda x)$, when acting on Wiener amalgam spaces $W(L^p,L^q)$. Scaling arguments are also used to prove the sharpness of the known convolution and pointwise relations for modulation spaces $M^{p,q}$, as well as the optimality of an estimate for the Schr\"odinger propagator on modulation spaces.Comment: 12 page

The Cauchy Problem for the Vibrating Plate Equation in modulation spaces

The local solvability of the Cauchy problem for the nonlinear vibrating plate equation is showed in the framework of modulation spaces. In the opposite direction, it is proved that there is no local wellposedness in Wiener amalgam spaces even for the solution to the homogeneous vibrating plate equation.Comment: 2 figures, some misprints correcte