Document downloaded from: http://hdl.handle.net/10251/43075 This paper must be cited as: Bonet Solves, JA.; Albanese, AA.; Ricker, WJ. (2013). Convergence of arithmetic means of operators in Fréchet spaces. Journal of Mathematical Analysis and Applications. 401(1):160-173. doi:10.1016/j.jmaa.2012.11.060. The final publication is available at http://dx.doi.org/10.1016/j.jmaa.2012.11.060 Copyright Elsevier CONVERGENCE OF ARITHMETIC MEANS OF OPERATORS IN FRÉCHET SPACES ANGELA A. ALBANESE, JOSÉ BONET* AND WERNER J. RICKER Authors' addresses: Angela A. Albanese: Dipartimento di Matematica e Fisica E. De Giorgi, Università del Salento- C.P.193, I-73100 Lecce, Italy email:
[email protected] José Bonet (corresponding author): Instituto Universitario de Matemática Pura y Aplicada IUMPA, Universitat Politècnica de València, E-46071 Valencia, Spain email:
[email protected] telephone number: +34963879497. fax number: +34963879494. Werner J. Ricker: Math.-Geogr. Fakultät, Katholische Universität Eichstätt- Ingolstadt, D-85072 Eichstätt, Germany email:
[email protected] Abstract. Every Köthe echelon Fréchet space X that is Montel and not isomorphic to a countable product of copies of the scalar eld admits a power bounded continuous linear operator T such that I ¡ T does not have closed range, but the sequence of arithmetic means of the iterates of T converge to 0 uniformly on the bounded sets in X. On the other hand, if X is a Fréchet space which does not have a quotient isomorphic to a nuclear Köthe echelon space with a continuous norm, then the sequence of arithmetic means of the iterates of any continuous linear operator T (for which (1=n)T n converges to 0 on the bounded sets) converges uniformly on the bounded subsets of X, i.e., T is uniformly mean ergodic, if and only if the range of I ¡ T is closed.