NECESSARY AND SUFFICIENT CONDITIONS OF FIRST ORDER NEUTRAL DIFFERENTIAL EQUATIONS.

In this work, we establish the necessary and sufficient conditions for oscillation of a class of functional differential equations of the form ((x(t)+p(t)x(to))' + q(t)(x(tr)) + v(t)(x( - )) = 0 of a neutral coefficient p(t), by using the Knaster-Tarski fixed point theorem and Banach's fixed point theorem. [ABSTRACT FROM AUTHOR]