Investigation of oscillation behaviour of solutions of first order delay differential equations

There are five chapters in this thesis. The first part is devoted to a literature review on delay differential equations. In the second part, there are definitions and theorems including delay differential equations. In the third chapter, the oscillation criteria for the solutions of constant coefficient-constant delay and variable coefficient-variable delay differential equations, which are expressed as follows, are given. There are findings and discussion section in the forth part and conclusion part in the last part.