Ensembles absorbants pour les classes projectives

Wydawnictwa / Czasopisma IMPAN / Fundamenta Mathematicae / Wszystkie zeszyty

Robert Cauty Fundamenta Mathematicae 143 (1993), 203-206 DOI: 10.4064/fm-143-3-203-206

We prove the existence, in the Hilbert space, of an absorbing set for the nth projective class.