Maseno University Repository

Browsing Department of Mathematics by Issue Date

Browsing Department of Mathematics by Issue Date

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  • JO Agure (Cambridge University Press, 1996-02)
    This paper investigates a certain type of numerical range introduced by Stampfli. In particular, we investigate the convexity of this set of elements of operators on Hilbert spaces and its relationship to the algebra ...
  • Paul O Oleche, Naftali O Ongati, John O Agure (JOOUST, 2009)
    A bounded operator with the spectrum lying in a compact set V ⊂ R, has C∞(V ) functional calculus. On the other hand, an operator H acting on a Hilbert space H, admits a C(R) functional calculus if H is self-adjoint. So ...
  • Paul O Oleche, N Omolo-Ongati, John O Agure (International Journal of Pure and Applied Mathematics, 2009-03)
    A closed densely defined operator H, on a Banach space X, whose spectrum is contained in R and satisfies
  • John O Agure, Paul O Oleche (Int. Journal of Math, 2010)
    This paper follows [1] in the quantitative study of Numerical Ranges introduced by Stampfli [9]. In particular, we consider a family of mutually orthogonal projections and investigate how a numerical range can be related ...
  • Paul O Oleche, John O Agure (Int. Journal of Math. Analysis,, 2010)
    A closed densely defined operator H, on a Banach space X, whose spectrum is contained in R and satisfies (z − H)−1 ≤ c z α | z|β ∀ z ∈ R with z α := |z|2 + 1 (1) for some α , β ≥ 0; c > 0, is said to ...
  • Shem Aywa, JO Agure, W Rao (Vdm verlag Dr. Muller aktiengeselischaft & co. kg., 2010)
    A sequence (uj)j2N of operators in L(X; Y ) is a (p; q)-summing multi- plier (or (p; q)-summing sequence of operators), in short (uj) 2 `¼p;q (X; Y ), if there exists a constant C > 0 such that, for any ¯nite collection ...
  • JO Bonyo, JO Agure (Int. Journal of Math. Analysis, 2010)
    Let B(H) be the algebra of bounded linear operators on a Hilbert space H and J be a norm ideal in B(H). We investigate the relationship between the diameter of the numerical range of an operator A ∈ B(H) and the norm ...
  • JO Bonyo, JO Agure (Int J Math Anal, 2010)
    We characterize when the norm of inner derivation on a norm ideal equals that on the quotient algebra. We further investigate norms of inner derivations implemented by normal and hyponormal operators on norm ...
  • JO Bonyo, JO Agure (International Journal of Mathematical Analysis, 2011)
    Let H be a complex Hilbert space and B(H) the algebra of all bounded linear operators on H. For A, B ∈ B(H), we define inner derivations implemented by A,B respectively on B(H) by ΔA(X) = AX−XA, ΔB(X) = BX−XB and a ...
  • JO Bonyo, DO Adicka, JO Agure (Applied Mathematical Sciences, 2011)
    In this paper, we extend the generalized Reid inequality to include the numerical radii for the product of two Hilbert space operators. Mathematics Subject Classification: 47A12, 47A30, 47A63
  • NB Okelo, JO Agure (SAMSA 2012 mathematics conference proceedings, 2012-11)
    Malaria is a major public health concern, especially among pregnant women and children under the age of five. It is a leading cause of morbidity and mortality in Malawi, accounting for fourty percent of out-patient ...
  • Mugisha Joseph Ong’ala Jacob Otieno, Oleche Paul (2013)
    There are major advances which have been made to understand the epidemiology of infectious diseases. However, more than 2 million children in the developing countries still die from pneumonia each year. The efforts to ...
  • John Ogonji Agure, David Otieno Ambogo, Fredrick Oluoch Nyamwala (WILEY‐VCH Verlag, 2013-03)
    Using subspace theory together with appropriate smoothness and decay conditions, we calculated the deficiency indices and absolutely continuous spectrum of fourth order difference equations with unbounded coefficients. In ...
  • Donnie Munyao Kasyoki (African Institute for Mathematical Sciences, Master Thesis, 2013-05-23)
    In this research project, we seek to address the problem of deciding which nite simple graph is a prime graph of a nite group. In particular, we only focus on showing which 4-regular graphs can be prime graphs of some ...
  • NB Okelo, JO Agure, PO Oleche (Elsevier, 2013-09-01)
    In this paper, we present various notions and aspects of orthogonality in normed spaces. Characterizations and generalizations of orthogonality are also considered. Results on orthogonality of the range and the kernel of ...
  • DO Adicka, W Mukuna, PO Oleche (Hikari Ltd, 2014)
    In this paper, we give a characterization of scalar operators. In particular we show that a densely defined closed linear operator H acting on a reflexive Banach space X is scalar if it is of (0, 1) type R and f (H)≤ f∞ ...
  • Ong’ala Jacob Otieno, Mugisha Joseph,Oleche Paul, (cience Publishing Group, 2014)
    Deterministic models have been used in the past to understand the epidemiology of infectious diseases, most importantly to estimate the basic reproduction number, Ro by using disease parameters. However, the approach ...
  • J Otieno, JYT Mugisha, BK Nannyonga, P Oleche (HIKARI Ltd, 2014)
    In this paper we study the disease dynamics of trypanosomiasis in a cattle population. The compartmental model presented includes the wild animal population which provides an alternative feeding source for the tsetse ...
  • Denis Njue Kingangi, John Ogoji Agure, Fredrick Oluoch Nyamwala (Scientific Research Publishing, 2014-07-07)
    The norm of an elementary operator has been studied by many mathematicians. Varied results have been established especially on the lower bound of this norm. Here, we attempt the same problem for finite dimensional operators.
  • Job Otieno Bonyo (Mississippi State University, 2015)
    The study of integral operators on spaces of analytic functions has been considered for the past few decades. However, most of the studies in this line are based on spaces of analytic functions of the unit disc. For the ...

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