Sobczyk's Theorems from A to B

Autores: David Yost, Félix Cabello Sánchez , Jesús María Fernández Castillo
Localización: Extracta mathematicae, ISSN-e 0213-8743, Vol. 15, Nº 2, 2000, págs. 391-420
Idioma: inglés
Títulos paralelos:
- Teoremas de Sobczyk de A a B
Enlaces
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Resumen
- Sobczyk's theorem is usually stated as: every copy of c0 inside a separable Banach space is complemented by a projection with norm at most 2. Nevertheless, our understanding is not complete until we also recall: and c0 is not complemented in l8. Now the limits of the phenomenon are set: although c0 is complemented in separable superspaces, it is not necessarily complemented in a non-separable superspace, such as l8.