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Some inequalities for the Fourier transform and their limiting behaviour

Analysis, Dynamics, and Applications Seminar

Some inequalities for the Fourier transform and their limiting behaviour
Series: Analysis, Dynamics, and Applications Seminar
Location: MATH 402
Presenter: Nicola Garofalo, Mathematical and Statistical Sciences, Arizona State University

The theorem of Hausdorff-Young states that when p is between 1 and 2, the Fourier transform of a function in L^p belongs to the dual Lebesgue space L^p’. One of the most famous (partly) open problems in classical analysis is the restriction conjecture. The latter asks when the Fourier transform of a function in L^p admits a restriction to L^q of the unit sphere. Since such manifold has measure zero, and since by Hausdorff-Young the Fourier transform is in L^p’, it is all but clear that such restriction be possible. A celebrated theorem of Tomas and Stein states that the restriction conjecture is true, at least when the target space is L^2 of the sphere. In this talk I identify a one-parameter family of inequalities for the Fourier transform whose limiting case is the restriction conjecture. Using Stein's method of complex interpolation I prove the conjectured inequalities when the target space is $L^2$,  and show that this recovers in the limit the Tomas-Stein theorem. 

 Place: Math Building, Room 402  https://map.arizona.edu/89