Mustafayev, Heybetkulu2025-05-102025-05-1020200378-620X1420-898910.1007/s00020-020-02591-82-s2.0-85088791897https://doi.org/10.1007/s00020-020-02591-8https://hdl.handle.net/20.500.14720/7049Let A, T, and B be bounded linear operators on a Banach space. This paper is concerned mainly with finding some necessary and sufficient conditions for convergence in operator norm of the sequences {A(n)TB(n)} and {1/n Sigma(n-1)(i=0) A(i)TB(i)}. These results are applied to the Toeplitz, composition, and model operators. Some related problems are also discussed.eninfo:eu-repo/semantics/closedAccessHilbert SpaceBanach SpaceCompact OperatorToeplitz OperatorComposition OperatorModel OperatorLocal SpectrumOperator SequenceOperator AverageConvergenceArticle924Q3Q3WOS:000554730000001