Lutz, Dieter Compactness properties of operator cosine functions. (English) Zbl 0448.47021 C. R. Math. Acad. Sci., Soc. R. Can. 2, 277-280 (1980). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 2 Documents MSC: 47D99 Groups and semigroups of linear operators, their generalizations and applications 39B52 Functional equations for functions with more general domains and/or ranges 47B06 Riesz operators; eigenvalue distributions; approximation numbers, \(s\)-numbers, Kolmogorov numbers, entropy numbers, etc. of operators Keywords:operator cosine functions PDFBibTeX XMLCite \textit{D. Lutz}, C. R. Math. Acad. Sci., Soc. R. Can. 2, 277--280 (1980; Zbl 0448.47021)