Cobos Díaz, Fernando2023-06-202023-06-2019900039-3223https://hdl.handle.net/20.500.14352/57341We show that the classical Lions-Peetre compactness theorems for Banach spaces (which are the main tools for proving all known compactness results in interpolation theory) fail in the locally convex case. We also prove a positive result assuming compactness of the operator in both sides.engjournal articlehttp://www.icm.edu.pl/restricted access517.98Análisis funcional y teoría de operadores