Means of positive matrices: geometry and a conjecture.
Means of vector-valued functions and projections which commute with the action of a group
Measures of Non-strict-singularity and Non-strict-cosingularity
Measures of non-strict-singularity of operators
Meromorphic functional calculus and local spectral theory.
Method of orthogonal projections and approximation of the spectrum of a bounded operator II
Method of orthogonal projections and approximation of the spectrum of a bounded operator
Méthode fonctionnelle en théorie des champs
Metrics in the set of partial isometries with finite rank
Let be the set of partial isometries with finite rank of an infinite dimensional Hilbert space . We show that is a smooth submanifold of the Hilbert space of Hilbert-Schmidt operators of and that each connected component is the set , which consists of all partial isometries of rank . Furthermore, is a homogeneous space of , where is the classical Banach-Lie group of unitary operators of , which are Hilbert-Schmidt perturbations of the identity. We introduce two Riemannian metrics...
M-Ideals of Compact Operators.
Minimal multi-convex projections
We say that a function from is k-convex (for k ≤ L) if its kth derivative is nonnegative. Let P denote a projection from X onto V = Πₙ ⊂ X, where Πₙ denotes the space of algebraic polynomials of degree less than or equal to n. If we want P to leave invariant the cone of k-convex functions (k ≤ n), we find that such a demand is impossible to fulfill for nearly every k. Indeed, only for k = n-1 and k = n does such a projection exist. So let us consider instead a more general “shape” to preserve....
Minimal projections with respect to various norms
A theorem of Rudin permits us to determine minimal projections not only with respect to the operator norm but with respect to various norms on operator ideals and with respect to numerical radius. We prove a general result about N-minimal projections where N is a convex and lower semicontinuous (with respect to the strong operator topology) function and give specific examples for the cases of norms or seminorms of p-summing, p-integral and p-nuclear operator ideals.
Minimalflächen mit polygonalem Rand.
Minimaxprinzipe zur Bestimmung der Eigenwerte J-nichtnegativer Operatoren.
Minimization of constrained quadratic forms in Hilbert spaces.
Mittelergodische Halbgruppen linearer Operatoren
A semigroup in , a Banach space, is called mean ergodic, if its closed convex hull in has a zero element. Compact groups, compact abelian semigroups or contractive semigroups on Hilbert spaces are mean ergodic.Banach lattices prove to be a natural frame for further mean ergodic theorems: let be a bounded semigroup of positive operators on a Banach lattice with order continuous norm. is mean ergodic if there is a -subinvariant quasi-interior point of and a -subinvariant strictly...
Mixed-type reverse order law and its equivalents
We present new results related to various equivalents of the mixed-type reverse order law for the Moore-Penrose inverse for operators on Hilbert spaces. Recent finite-dimensional results of Tian are extended to Hilbert space operators.
Möbius transformations and monogenic functional calculus.
Modal stabilizability and spectral synthesis
Modèle de Jordan pour des contractions sur l'espace de Hilbert