Jiménez Sevilla, María Del MarLajara, Sebastián2024-05-272024-05-2720231422-63831420-901210.1007/s00025-023-02022-1https://hdl.handle.net/20.500.14352/1044692023 Acuerdos transformativos CRUEWe present a result which generalizes the theorems of Gurariy-Kadets and Lindenstrauss-Rosenthal on quasicomplemented subspaces of Banach spaces. We also provide a solution in wide classes of Banach spaces of a problem posed by Ivan Singer concerning the existence of a w*-basic sequence in the dual of a Banach space which is biorthogonal to a given basic sequence (or more generally, a given minimal sequence) in that space, and other related problems.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/journal articlehttps://doi.org/10.1007/s00025-023-02022-1open accessBanach spaceQuasicomplemented subspaceSeparable quotientw*-basic sequenceCountable union of operator rangesAnálisis funcional y teoría de operadores1202 Análisis y Análisis Funcional