The paper considers the so-called strict -numbers, which form an important subclass of the family of all -numbers. For operators acting between Hilbert spaces the various -numbers are known to coincide: here we give examples of linear maps and non-Hilbert spaces such that all strict -numbers of coincide. The maps considered are either simple integral operators acting in Lebesgue spaces or Sobolev embeddings; in these cases the exact value of the strict -numbers is determined.
Cite this article
David E. Edmunds, Jan Lang, Coincidence and Calculation of some Strict -Numbers. Z. Anal. Anwend. 31 (2012), no. 2, pp. 161–181DOI 10.4171/ZAA/1453