Construction of positive definite functions
Convolution Quotients of Nonnegative Functions.
Convolution Semigroups and Resolvent Families of Measures on Hypergroups.
Decomposition of Positive Definite Functions Defined on a Neighbourhood of the Identity.
Definisierbare Funktionen auf Gruppen [Book]
Die Frobeniuseigenschaft FP für diskrete Gruppen.
Die unzerlegbaren Charaktere einiger diskreter Gruppen.
Dilations of Hilbert space operators (General theory) [Book]
Directionally Euclidean structures of Banach spaces
We study Banach spaces with directionally asymptotically controlled ellipsoid-approximations of the unit ball in finite-dimensional sections. Here these ellipsoids are the unique minimum volume ellipsoids, which contain the unit ball of the corresponding finite-dimensional subspace. The directional control here means that we evaluate the ellipsoids by means of a given functional of the dual space. The term 'asymptotical' refers to the fact that we take 'lim sup' over finite-dimensional subspaces. ...
Distances hilbertiennes invariantes sur un espace homogène
Nous déterminons pour certains espaces homogènes les distances invariantes qui proviennent d’un plongement de dans un espace de Hilbert. Le carré d’une telle distance est un noyau de type négatif invariant dont nous donnons une représentation, c’est la formule de Lévy-Kinchine. Nous en déduisons que si possède la propriété (T) de Kajdan une telle distance est toujours bornée.
Distributions of Positive Type and Representations of Lie Groups.
Existence of Sidon sets of first kind in LCA groups
Extension of multiplicative families of isometries. (Extensión de familias multiplicativas de isometrías.)
Extreme positive definite double sequences which are not moment sequences.
From the fact that the two-dimensional moment problem is not always solvable, we can deduce that there must be extreme ray generators of the cone of positive definite double sequences which are nor moment sequences. Such an argument does not lead to specific examples. In this paper it is shown how specific examples can be constructed if one is given an example of an N-extremal indeterminate measure in the one-dimensional moment problem (such examples exist in the literature). Konrad Schmüdgen had...
Formes quadratiques sur un semi-groupe involutif.
Functions with a Finite Number of Negative Squares on Semigroups.
Harmonic Analysis and Real Group Algebras.
Harmonic analysis of symmetric random graphs
This note attempts to understand graph limits as defined by Lovasz and Szegedy in terms of harmonic analysis on semigroups. This is done by representing probability distributions of random exchangeable graphs as mixtures of characters on the semigroup of unlabeled graphs with node-disjoint union, thereby providing an alternative derivation of de Finetti's theorem for random exchangeable graphs.
Helical maps from LCA-groups into Hilbert spaces.
Holomorphic representation theory. I.