FORCED OSCILLATIONS OF NONLINEAR PARABOLIC EQUATIONS WITH FUNCTIONAL ARGUMENTS
There has been much current interest in studying the oscillation of parabolic equations with functionai arguments (cf. Bainov and Mishev [1]). To the author's knowledge, the first results in this direction were given by Bykov and Kultaev [2]. We refer the reader to [3, 5, 6, 7, 1012, 14] for parabolic equations (or systems) without forcing term, and to [8, 9, 15, 16] for the forced oscillations. In particular, Kreith and Ladas [7] have investigated the oscillation of parabolic equations with positive and negative coeflicients. The purpose of this paper is to extend the results of [7] to the more general equations with forcing term. We are concemed with the forced oscillations of the parabolic equation with functionai arguments