Fourier transformation and endoscopy. (Transformation de Fourier et endoscopie.)
Fourier transforms of representations of quaternions.
Fourier-like kernels in geometric quantization [Book]
Fourier-Stieltjes algebras of compact extensions of nilpotent groups.
Fraïssé structures and a conjecture of Furstenberg
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...
Free actions of free groups on countable structures and property (T)
We show that if G is a non-archimedean, Roelcke precompact Polish group, then G has Kazhdan's property (T). Moreover, if G has a smallest open subgroup of finite index, then G has a finite Kazhdan set. Examples of such G include automorphism groups of countable ω-categorical structures, that is, the closed, oligomorphic permutation groups on a countable set. The proof uses work of the second author on the unitary representations of such groups, together with a separation result for infinite permutation...
Free Compact Abelian Groups
Free fall motion in an invariant field of forces: the 2D-case.
Free groups and semigroups in ßN.
Free groups in ßN which miss the minimal ideal.
Free groups of semigroups in semi-simple Lie groups.
Free non-archimedean topological groups
We study free topological groups defined over uniform spaces in some subclasses of the class of non-archimedean groups. Our descriptions of the corresponding topologies show that for metrizable uniformities the corresponding free balanced, free abelian and free Boolean groups are also metrizable. Graev type ultra-metrics determine the corresponding free topologies. Such results are in a striking contrast with free balanced and free abelian topological groups cases (in standard varieties). Another...
Free operators with operator coefficients
Free products of Lie groups
Free products of topological groups with equal uniformities, I
Free products of topological groups with equal uniformities, II
Free semigroups and unitary group representations
Free topological inverse semigroups.
Free topological vector spaces [Book]
Frequency functions on the Heisenberg group, the uncertainty principle and unique continuation
A recent result of Bahouri shows that continuation from an open set fails in general for solutions of where and is a (nonelliptic) operator in satisfying Hörmander’s condition for hypoellipticity. In this paper we study the model case when is the subelliptic Laplacian on the Heisenberg group and is a zero order term which is allowed to be unbounded. We provide a sufficient condition, involving a first order differential inequality, for nontrivial solutions of to have a finite order...