Department of Mathematics: Recent submissions

Now showing items 41-60 of 73

    • A cost - benefit analysis of substituting bamboo for tobacco: a case study of smallholder tobacco farmers in south Nyanza, Kenya 

      Wilfred Omwansa Peter Omari Magati, Jacob K. Kibwage, Seth Gor Omondi, George Ruigu (Science Journal Publication, 2012)
      This study examined the economic and financial benefits and costs of farming bamboo as a crop substitute of tobacco in four (4) districts in South Nyanza, Kenya. The World Health Organization Framework Convention on ...

    • A Functional Calculus for (α, α+ 1)− type R Operators 

      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 ...

    • On the convexity of Stampfli's numerical range 

      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 ...

    • Norm of a derivation and hyponormal operators 

      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 ...

    • Norms of Inner Derivations on Norm ideals 

      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 ...

    • Aspects of (pq) summing multipliers 

      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 ...

    • Orthogonality of elementary operators in normed spaces and their applications 

      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 ...

    • Deficiency indices and spectrum of fourth order difference equations with unbounded coefficients 

      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 ...

    • On the norm of elementary operator 

      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.

    • On the Numerical Range of a Generalized Derivation 

      FM Runji, JO Agure, FO Nyamwala (HIKARI Ltd,, 2017)
      We examine the relationship between the numerical range of the restriction of a generalized derivation to a norm ideal J and that of its implementing elements. Mathematics Subject Classi cation: 47A12; 47B47

    • On the maximal numerical range of elementary operators 

      Flora Mati Runji, John Ogonji Agure, Fredrick Oluoch Nyamwala (Academic Publications, Ltd., 2017-02)
      The notion of the numerical range has been generalized in different directions. One such direction, is the maximal numerical range introduced by Stampfli (1970) to derive an identity for the norm of a derivation on L(H). ...

    • Effects of Structural Viscoelasticity in Non-Divergence free Deformable Porous Media with Incompressible Constituents 

      Micheal Babatunde Oguntola, Mathew Ngugi Kinyanjui, John Agure Ogonji (Global Journal of Pure and Applied Mathematics, 2018)
      In this paper, we investigate the importance of structural viscoelasticity in the mechanical response of deformable porous media with incompressible constituents under sudden changes in the external applied quasi-static ...

    • On Numerical Range of Multiplication Operator 

      Odero Adhiambo Beatrice, JO Agure, FO Nyamwala (International Journal of Mathematical Analysis, 2019)
      Let H be an in nite dimensional complex Hilbert space and A;B 2 B(H) where B(H) is the C -algebra of all bounded linear operators on H. Let MAB : B(H) ! B(H) be a multiplication operator induced by A and B de- ned ...

    • Finite Solvable Groups with 4-Regular Prime Graphs 

      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 ...

    • The algebra of smooth functions of rapid descent 

      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 ...

    • Operators with slowly growing resolvents towards the spectrum 

      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

    • On Numerical and Centre Values Range 

      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 ...

    • Mathematical Model for Pneumonia Dynamics with Carriers 

      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 ...

    • Various notions of orthogonality in normed spaces 

      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 ...

    • On necessary Conditions for scalars 

      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∞ ...