Entropy of -valued operators and diverse applications.
Error-estimates for the method of least squares of finding eigenvalues and eigenfunctions
Espaces de Krein et index des systèmes hamiltoniens
Explicit representation of compact linear operators in Banach spaces via polar sets
We consider a compact linear map T acting between Banach spaces both of which are uniformly convex and uniformly smooth; it is supposed that T has trivial kernel and range dense in the target space. It is shown that if the Gelfand numbers of T decay sufficiently quickly, then the action of T is given by a series with calculable coefficients. This provides a Banach space version of the well-known Hilbert space result of E. Schmidt.