Browsing by Author "Obogi, R. K."

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    • Certain properties of normaloid operators 

      Mogotu, P.O.; Kerongo, J.; Obogi, R. K.; Okelo, Bernad N. (JOOUST, 6/24/2015)
      In this paper we establish new conditions for contractivity of normaloid operators. We employ some results for contractivity due to Furuta, Nakomoto, Arandelovic and Dragomir. A particular generalization is also given.

    • Conditions for Positivity of Operators in Non-unital C*-algebras 

      Obogi, R. K.; Bosire, J. N.; Okelo, N. B.; Ongati, Omolo (International Journal of Mathematical Analysis, 1/9/2015)
      In this paper, we present results on the necessary and sufficient condi-tions for positivity of operators in non-unital C*- algebras

    • Generalizations on normal self-ad joint operators 

      Omaoro, Sabasi; Kerongo, J.; Obogi, R. K.; Okelo, Bernad N. (JGRMA, 2017-09)
      We consider certain properties of operators. A lot of studies have been done on reflexivity, compactness and numerical radius attainability on Hilbert space operators [1-12] and the reference therein.

    • On Norm Estimates for Derivations in Norm-Attainable Classes 

      Nyabonyi, J. Z.; Okelo, N. B.; Obogi, R. K. (Eur. J. Math. Anal, 2023)
      In this note, we provide detailed characterization of operators in terms of norm-attainability and norm estimates in Banach algebras. In particular, we establish the necessary and sufficient conditions for norm-attainability ...