Uber Nichtlineare Kompakte Storungen von Kompakten Linearen Operatoren
On montre que si est un espace vectoriel réticulé, le cône des formes linéaires positives sur , muni de la topologie de la convergence simple sur est un cône biréticulé.Ce résultat conduit à une nouvelle définition des cônes biréticulés, équivalents à la définition initiale, mais d’un usage beaucoup plus souple ; ce résultat est la réponse positive à une hypothèse de G. Choquet.
We prove that the quasi-Banach spaces and (0 < p < 1) have a unique unconditional basis up to permutation. Bourgain, Casazza, Lindenstrauss and Tzafriri have previously proved that the same is true for the respective Banach envelopes and ℓ₁(ℓ₂). They used duality techniques which are not available in the non-locally convex case.
The area of research of this paper goes back to a 1930 result of H. Auerbach showing that a scalar series is (absolutely) convergent if all its zero-density subseries converge. A series in a topological vector space X is called ℒ-convergent if each of its lacunary subseries (i.e. those with ) converges. The space X is said to have the Lacunary Convergence Property, or LCP, if every ℒ-convergent series in X is convergent; in fact, it is then subseries convergent. The Zero-Density Convergence...