Bombal Gordón, Fernando2023-06-202023-06-2019920-444-89378-410.1016/S0304-0208(08)70327-Xhttps://hdl.handle.net/20.500.14352/57200Progress in Functional Analysis Proceedings of the International Functional Analysis Meeting on the Occasion of the 60th Birthday of Professor M. Valdivia INTERNATIONAL FUNCTIONAL ANALYSIS MEETING ON THE OCCASION OF THE 60TH BIRTHDAY OF PROFESSOR M VALDIVIA.OCT 22-27, 1990.PENISCOLA, SPAIN.We characterize several classes of subsets in the Λ-sum (ΣEn)Λ of a sequence (En) of Banach spaces (where A is a Banach sequence ideal space), in terms of the corresponding classes in the spaces En. Several stability results are obtained.journal articlehttp://www.sciencedirect.com/science/bookseries/03040208http://www.sciencedirect.commetadata only access517.986.6Distinguished subsetsVector sequence spacesWeakly unconditionally convergent seriesPerfect Banach sequence spaceComplemented copy of c0Análisis matemático1202 Análisis y Análisis Funcional