Uniformly continuous functionals on Banach algebras
Uniformly continuous functions on compact semigroups
Uniformly cyclic vectors
A group acting on a measure space (X,β,λ) may or may not admit a cyclic vector in . This can occur when the acting group is as big as the group of all measure-preserving transformations. But it does not occur, even though there is no cardinality obstruction to it, for the regular action of a group on itself. The connection of cyclic vectors to the uniqueness of invariant means is also discussed.
Unimodularity and Atomic Plancerel Measure.
Unions et intersections d’espaces invariantes par translation ou convolution
Étude des propriétés des unions et intersections d’espaces relatifs à un ensemble de mesures positives sur un groupe commutatif localement compact lorsque est invariant par translation ou stable par convolution.Dans des cas particuliers, on retrouve les propriétés d’espaces étudiés par A. Beurling et par B. Koremblium.On étudie aussi les espaces formés des fonctions appartenant localement à et qui ont un comportement à l’infini.
Unipotent orbital integrals of spherical functions on p-adic 4 X 4 symplectic groups.
Unique Disintegration of Arbitraty Positive Definite Functions on *-divisible Semigroups.
Uniqueness of complete norms for quotients of Banach function algebras
We prove that every quotient algebra of a unital Banach function algebra A has a unique complete norm if A is a Ditkin algebra. The theorem applies, for example, to the algebra A (Γ) of Fourier transforms of the group algebra of a locally compact abelian group (with identity adjoined if Γ is not compact). In such algebras non-semisimple quotients arise from closed subsets E of Γ which are sets of non-synthesis. Examples are given to show that the condition of Ditkin cannot be relaxed. We construct...
Uniqueness of rotation invariant norms.
Uniqueness of the topology on L¹(G)
Let G be a locally compact abelian group and let X be a translation invariant linear subspace of L¹(G). If G is noncompact, then there is at most one Banach space topology on X that makes translations on X continuous. In fact, the Banach space topology on X is determined just by a single nontrivial translation in the case where the dual group Ĝ is connected. For G compact we show that the problem of determining a Banach space topology on X by considering translation operators on X is closely related...
Unitary Banach algebras
In a Banach algebra an invertible element which has norm one and whose inverse has norm one is called unitary. The algebra is unitary if the closed convex hull of the unitary elements is the closed unit ball. The main examples are the C*-algebras and the ℓ₁ group algebra of a group. In this paper, different characterizations of unitary algebras are obtained in terms of numerical ranges, dentability and holomorphy. In the process some new characterizations of C*-algebras are given.
Unitary closure and Fourier algebra of a topological group
This is a sequel to our recent work (2012) on the Fourier-Stieltjes algebra B(G) of a topological group G. We introduce the unitary closure G̅ of G and use it to study the Fourier algebra A(G) of G. We also study operator amenability and fixed point property as well as other related geometric properties for A(G).
Unitary dilations of multi-parameter semigroups of operators
Unitary multipliers on
Unitary representations induces from compact subgroups
Unitary representations of solvable Lie groups
Universal mapping properties of semigroup compactifications.
Un'osservazione su un criterio di compattezza per le funzioni vettoriali quasi periodiche
Utilisation des produits de Riesz pour minorer la dimension de Hausdorff de certains ensembles.