Formal degree and existence of stable arithmetic lattices of cuspidal representations of p-adic reductive groups.
Nous prouvons la formule de Plancherel pour les fonctions de Whittaker sur un groupe réductif p-adique. Les méthodes sont proches de celles de la preuve de Waldspurger, d’après Harish-Chandra, pour les fonctions lisses sur le groupe.Au delà du résultat, ce travail met en place un cadre qui devrait s’avérer utile pour d’autres formules de Plancherel, notamment pour les espaces symétriques réductifs p-adiques. En particulier, il met en valeur le role des matrices B et de leur propriété d’adjonction....
For an eigenfunction of the Laplacian on a hyperbolic Riemann surface, the coefficients of the Fourier expansion are described as intertwining functionals. All intertwiners are classified. A refined growth estimate for the coefficients is given and a summation formula is proved.
Let H₁ be the 3-dimensional Heisenberg group. We prove that a modified version of the spherical transform is an isomorphism between the space 𝓢ₘ(H₁) of Schwartz functions of type m and the space 𝓢(Σₘ) consisting of restrictions of Schwartz functions on ℝ² to a subset Σₘ of the Heisenberg fan with |m| of the half-lines removed. This result is then applied to study the case of general Schwartz functions on H₁.
We study problems concerning the Samuel compactification of the automorphism group of a countable first-order structure. A key motivating question is a problem of Furstenberg and a counter-conjecture by Pestov regarding the difference between , the Samuel compactification, and , the enveloping semigroup of the universal minimal flow. We resolve Furstenberg’s problem for several automorphism groups and give a detailed study in the case of , leading us to define and investigate several new types...