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math.FA2026
On the existence of extremizers for the sum of eigenvalues of Toeplitz operators
Fabio Nicola, Federico Riccardi, Paolo Tilli
We prove that, among all measurable sets of prescribed Lebesgue measure, there exists a set maximizing the sum of the first eigenvalues () of the…
math.AP2026
A Phase Space Criterion for Dynamical Amrein-Berthier Uncertainty
Piero D'Ancona, Diego Fiorletta, Fabio Nicola
We prove a phase space criterion for dynamical Amrein-Berthier uncertainty principles. The abstract result says that, for a Fourier integral operator associated with…