Now showing items 1-20 of 39

    • On phi-Dedekind rings and phi-Krull rings 

      Badawi, Ayman; Anderson, David F. (University of Houston, 2005)
      The purpose of this paper is to introduce two new classes of rings that are closely related to the classes of Dedekind domains and Krull domains. Let H = {R | R is a commutative ring with 1 and Nil(R) is a divided prime ...
    • On phi-Mori rings 

      Badawi, Ayman; Lucas, Thomas G. (University of Houston, 2006)
      A commutative ring R is said to be a phi-ring if its nilradical Nil(R) is both prime and comparable with each principal ideal. The name is derived from the natural map phi from the total quotient ring T(R) to R localized ...
    • Strong ring extensions andphi-pseudo-valuation rings 

      Badawi, Ayman; Dobbs, David E. (University of Houston, 2006)
      In this paper, we extend the concept of strong extensions of domains to the context of (commutative) rings with zero-divisors. We show that the theory of strong extensions of rings resembles that of strong extensions of domains.
    • Martingale problem for superprocesses with non-classical branching functional 

      Leduc, Guillaume (Elsevier, 2006)
      The martingale problem for superprocesses with parameters (𝛏, Ф, 𝑘) is studied where 𝑘(𝒹𝑠) may not be absolutely continuous with respect to the Lebesgue measure. This requires a generalization of the concept of ...
    • An Extension of Sharkovsy’s Theorem to Periodic Difference Equations 

      Al-Sharawi, Ziyad; Angelos, James; Elaydi, Saber; Rakesh, Leela (Elsevier, 2006)
      We present an extension of Sharkovsky’s Theorem and its converse to periodic difference equations. In addition, we provide a simple method for constructing a p-periodic difference equation having an r-periodic geometric ...
    • On the periodic logistic equation 

      Al-Sharawi, Ziyad; Angelos, James (Elsevier, 2006)
      We show that the 𝒑-periodic logistic equation 𝒳ₙ₊₁ = μₙ mod 𝒑𝒳ₙ(1 - 𝒳ₙ) has cycles (periodic solutions) of minimal periods 1; 𝒑; 2𝒑; 3𝒑; …. Then we extend Singer’s theorem to periodic difference equations, and use ...
    • Some finiteness conditions on the set of overrings of a phi-ring 

      Badawi, Ayman; Jaballah, Ali (University of Houston, 2008)
      Let H = {R | R is a commutative ring and Nil(R) is a divided prime ideal of R}. For a ring R in H with total quotient ring T(R), Let phi be the natural ring homomorphism from T(R) into R_Nil(R). An integral domain R is ...
    • Exercisability Randomization of the American Option 

      Leduc, Guillaume (Taylor & Frances Online, 2008)
      The valuation of American options is an optimal stopping time problem which typically leads to a free boundary problem. We introduce here the randomization of the exercisability of the option. This method considerably ...
    • Existence and stability of periodic orbits of periodic difference equations with delays 

      Al-Sharawi, Ziyad; Angelos, James; Elaydi, Saber (World Scientific Publishing, 2008)
      In this paper, we investigate the existence and stability of periodic orbits of the p-periodic difference equation with delays xₙ = f(n - 1, xₙ₋ₖ). We show that the periodic orbits of this equation depend on the periodic ...
    • Periodic Orbits in Periodic Discrete Dynamics 

      Al-Sharawi, Ziyad (Elsevier, 2008)
      We study the combinatorial structure of periodic orbits of nonautonomous difference equations 𝒳ₙ₊₁ = 𝒇ₙ(𝒳ₙ) in a periodically fluctuating environment. We define the Ӷ-set to be the set of minimal periods that are not ...
    • The Beverton–Holt model with periodic and conditional harvesting 

      Al-Sharawi, Ziyad; Rhouma, Mohamed Ben Haj (Taylor & Francis Online, 2009)
      In this theoretical study, we investigate the effect of different harvesting strategies on the discrete Beverton–Holt model in a deterministic environment. In particular, we make a comparison between the constant, periodic ...
    • Coexistence and extinction in a competitive exclusion Leslie/Gower model with harvesting and stocking 

      Al-Sharawi, Ziyad; Rhouma, Mohamed Ben Haj (Taylor & Francis Online, 2009)
      The principle of competitive exclusion states that when the competition between species is sufficiently strong, only the dominant species survives. In this paper, we examine the strategies of using stocking and harvesting ...
    • The Discrete Beverton-Holt Model with Periodic Harvesting in a Periodically Fluctuating Environment 

      Al-Sharawi, Ziyad; Rhouma, Mohamed Ben Haj (Springer, 2010)
      We investigate the effect of constant and periodic harvesting on the Beverton-Holt model in a periodically fluctuating environment. We show that in a periodically fluctuating environment, periodic harvesting gives a better ...
    • Market Efficiency of Floating Exchange Rate Systems: Some Evidence from Pacific-Asian Countries 

      Al-Khazali, Osamah; Leduc, Guillaume; Pyun, Chong S. (Elsevier, 2011)
      This paper examines the random walk hypothesis (RWH) and the martingale difference hypothesis (MDH) for the Australian dollar and five Asian emerging currencies relative to three benchmark currencies. We use Wright’s (2000) ...
    • A new characterization of periodic oscillations in periodic difference equations 

      Al-Salman, Ahmad; Al-Sharawi, Ziyad (Elsevier, 2011-11)
      In this paper, we characterize periodic solutions of p-periodic difference equations. We classify the periods into multiples of p and nonmultiples of p. We show that the elements of the set of multiples of p follow the ...
    • Convergence rate of the binomial tree scheme for continuously paying options 

      Leduc, Guillaume (Université du Québec à Montréal, 2012)
      Continuously Paying Options (CPOs) form a very natural class of derivatives for hedging risks coming from adverse movements of a continuously traded asset. We study the rate of convergence of CPOs evaluated under the ...
    • On weakly 2-absorbing ideals of commutative rings 

      Badawi, Ayman; Darani, Ahmad Yousefian (University of Houston, 2013)
      Let R be a commutative ring with identity 1 not equal to 0. In this paper, we introduce the concept of a weakly 2-absorbing ideal. A proper ideal I of R is called a weakly 2-absorbing ideal of R if whenever abc is not equal ...
    • A European option general first-order error formula 

      Leduc, Guillaume (Cambridge, 2013)
      We study the value of European security derivatives in the Black-Scholes model, when the underlying asset 𝛏 is approximated by random walks 𝛏(𝑛). We obtain an explicit error formula, up to a term of order 𝒪(𝑛⁻³/² ), ...
    • A Global Attractor in Some Discrete Contest Competition Models with Delay under the Effect of Periodic Stocking 

      Al-Sharawi, Ziyad (Hindawi, 2013)
      We consider discrete models of the form 𝒳ₙ₊₁= 𝒳ₙ𝒇(𝒳ₙ₋₁) + 𝒉ₙ , where 𝒉ₙ is a nonnegative 𝒑-periodic sequence representing stocking in the population, and investigate their dynamics. Under certain conditions on the ...
    • The dynamics of some discrete models with delay under the effect of constant yield harvesting 

      Abu-Saris, Raghib; Al-Sharawi, Ziyad; Rhouma, Mohamed Ben Haj (Elsevier, 2013)
      In this paper, we study the dynamics of population models of the form xn+1 = xnf(xn−1) under the effect of constant yield harvesting. Results concerning stability, boundedness, persistence and oscillations of solutions are ...