RT Book, Section T1 On the set of bounded linear operators transforming a certain sequence of a Hilbert space into an absolutely summable one A1 Martín Peinador, Elena A2 Császár, Ákos AB From the text: "Let H be a real, separable Hilbert space, B the set of bounded linear operators on H, and S={an:n∈N} a fixed sequence in H; we set CS={A∈B:∑∞n=1||Aan||<∞}. Obviously CS≠{0}, and it is easy to check that CS is a left ideal. Theorem 1: Let S={an:n∈N} be summable. Then CS contains a noncompletely continuous operator. Theorem 2: Let S={an:n∈N} be such that ∑∞n=1||an|||=∞; then there exists a completely continuous operator C not belonging to CS.'' PB North-Holland SN 0444854061 YR 1980 FD 1980 LK https://hdl.handle.net/20.500.14352/65473 UL https://hdl.handle.net/20.500.14352/65473 LA eng NO Proceedings of the 4th Colloquium on Topology in Budapest, 7-11 Aug. 1978, organized by the Bolyai János Mathematical Society DS Docta Complutense RD 10 abr 2025