الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
Actually, we have greatly less results for third order differential equations than for the first or second order equations. So, the main objective of this thesis is to shed light on many equations of third order, through studying the asymptotic behavior of solutions of those equations by different methods and comparison of results. We discussed, in detail, the oscillation and the asymptotic behavior of solutions of the class of third order nonlinear delay differential equations. Specifically, the topics dealt with include the following:
Establishing a lower bound for the distance between zeros of a solution and or its derivatives. Finding conditions which ensure that the solutions of equation are either oscillatory or converges to zero. Applying the oscillation of third order difference equation on second order neutral difference equation.This thesis contains several remarks and illustrative examples as an application of our results. The thesis consists of four chapters:Chapter 1. This chapter is an introductory chapter and it deals with the problem of oscillation of third order functional differential equations. It contains some basic definitions, elementary results that will be used throughout the next chapters and most of the main results of oscillation for the third order differential equations that can be found in the literature.Chapter 2. In this chapter, we will establish lower bounds for the distance between zeros of a solution and or its derivatives of the equation by using some inequalities of Hardy’s type, Opial type and Wirtinger’s type that to prove our main results.Chapter 3. In this chapter, we are concerned with oscillation of solutions of the third order linear differential equation by using an invariant transformation which transforms the third order differential equation with damping term to a general third order differential equation. Chapter 4. In this chapter, we apply oscillation of third order difference equations on second nonlinear neutral delay difference equations.