Descriptive set theoretic methods applied to strictly singular and strictly cosingular operators

2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/162051The class of strictly singular operators originating from the dual of a separable Banach space is written as an increasing union of $ω_1$ subclasses which are defined using the Schreier sets. A question of J. Diestel, of whether a similar result can be stated for strictly cosingular operators, is studied.Functional Analysis47B07, 47A15Descriptive set theoretic methods applied to strictly singular and strictly cosingular operatorstext