For a two-sided sequence of compact linear operators acting on a Banach space, we consider the notion of spectrum defined in terms of the existence of exponential dichotomies under homotheties of the dynamics. This can be seen as a natural generalization of the spectrum of a matrix—the set of its eigenvalues. We give a characterization of all possible spectra and explicit examples of sequences for which the spectrum takes a form not occurring in finite-dimensional spaces. We also consider the case of a one-sided sequence of compact linear operators.
The first author and the third author were supported by FCT/Portugal through UID/MAT/04459/2013. The second author was supported in part by the Croatian Science Foundation under the project IP-2014-09-2285 and by the University of Rijeka under the project number 220.127.116.11.01.
"Spectrum for compact operators on Banach spaces." J. Math. Soc. Japan 71 (1) 1 - 17, January, 2019. https://doi.org/10.2969/jmsj/76447644