Toka Diagana
Howard University
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Publication
Featured researches published by Toka Diagana.
Applicable Analysis | 2007
Paul H. Bezandry; Toka Diagana
The article introduces and studies the concept of p-mean almost periodicity for stochastic processes. Our abstract results are, subsequently, applied to studying the existence of square-mean almost periodic solutions to some semilinear stochastic equations.
Proceedings of the American Mathematical Society | 2004
Toka Diagana; Gaston M. N'Guérékata; Nguyen Van Minh
This paper is concerned with the existence of almost automorphic mild solutions to equations of the form (*) u(t) = Au(t) + f(t), where A generates a holomorphic semigroup and f is an almost automorphic function. Since almost automorphic functions may not be uniformly continuous, we introduce the notion of the uniform spectrum of a function. By modifying the method of sums of commuting operators used in previous works for the case of bounded uniformly continuous solutions, we obtain sufficient conditions for the existence of almost automorphic mild solutions to (*) in terms of the imaginary spectrum of A and the uniform spectrum of f.
Archive | 2013
Toka Diagana
1. Metric, Banach, and Hilbert Spaces.- 2. Linear Operators on Banach Spaces.- 3. Almost Periodic Functions.- 4. Almost Automorphic Functions.- 5. Pseudo-Almost Periodic Functions.- 6. Pseudo-Almost Automorphic Functions.- 7. Existence Results for Some Second-Order Differential Equations.- 8. Existence Results to Some Integrodifferential Equations.- 9. Existence of C(m)-Pseudo-Almost Automorphic Solutions.- 10. Pseudo-Almost Periodic Solutions to Some Third-Order Differential Equations.- 11. Pseudo-Almost Automorphic Solutions to Some Sobolev-Type Equations.- 12. Stability Results for Some Higher-Order Difference Equations.- 13. Appendix A.- References.- Index.
Applicable Analysis | 2007
Toka Diagana; Gaston M. N’Guérékata
This article is concerned with the existence and uniqueness of an almost automorphic solution to the semilinear equation where is the infinitesimal generator of an exponentially stable C 0-semigroup on a Banach space and is Sp -almost automorphic for p > 1 and jointly continuous.
Archive | 2011
Paul H. Bezandry; Toka Diagana
Preface.-1. Banach and Hilbert Spaces.-2. Bounded and Unbounded Linear Operators.- 3.An Introduction to Stochastic Differential Equations.-4. P-th Mean Almost Periodic Random Functions.-5. Existence Results for Some Stochastic Differential Equations.-6. Existence Results for Some Partial Stochastic Differential Equations.-7.Existence Results for Some Second-Order Stochastic Differential Equations.-8. Mean Almost Periodic Random Sequences and Their Applications to Stochastic Difference Equations.-References.-Index.
Mathematical and Computer Modelling | 2007
Toka Diagana; Eduardo Hernández; Marcos Rabello
In this paper we give some sufficient conditions, which ensure the existence of pseudo almost periodic solutions to some classes of non-autonomous first-order partial neutral functional-differential with unbounded delay.
Applied Mathematics Letters | 2007
Toka Diagana; Gaston M. N’Guérékata
We give in this work some sufficient conditions for the existence and uniqueness of almost automorphic (mild) solutions to some classes of partial evolution equations. Then we use our abstract results to discuss the existence and uniqueness of almost automorphic solutions to some partial differential equations.
Applied Mathematics and Computation | 2012
Najja S. Al-Islam; Saud M. Alsulami; Toka Diagana
Abstract In this paper we first introduce two new concepts called respectively weighted pseudo periodicity and weighted pseudo anti-periodicity, which generalize respectively the well-known notions of periodicity and that of anti-periodicity. Basic properties of these new functions are discussed. Furthermore, the existence of weighted pseudo anti-periodic solutions to some damped non-autonomous second-order differential equations will be investigated. To illustrate our abstract results, the existence of weighted pseudo anti-periodic solutions to a plate-like equation is discussed.
Journal of Difference Equations and Applications | 2008
Paul H. Bezandry; Toka Diagana; Saber Elaydi
The paper studies a Beverton–Holt difference equation, in which both the recruitment function and the survival rate vary randomly. It is then shown that there is a unique invariant density, which is asymptotically stable. Moreover, a basic theory for random mean almost periodic sequence on is given. Then, some sufficient conditions for the existence of a mean almost periodic solution to the stochastic Beverton–Holt equation are given.
Journal of Difference Equations and Applications | 2007
Toka Diagana; Saber Elaydi; Abdul-Aziz Yakubu
We establish the basic theory of almost periodic sequences on ℤ+. Dichotomy techniques are then utilized to find sufficient conditions for the existence of a globally attracting almost periodic solution of a semilinear system of difference equations. These existence results are, subsequently, applied to discretely reproducing populations with and without overlapping generations. Furthermore, we access evidence for attenuance and resonance in almost periodically forced population models.