Necessary and sufficient conditions for oscillation of neutral delay parabolic differential equations

Necessary and sufficient conditions are established for the oscillation of neutral delay parabolic differential equations of the form partial / partial t[u(x,t) - pu(x,t - τ)] = a(t)Δu(x,t) + summation k=1sak(t)Δu(x,t - ρk(t)) - summation j=1mqj(t)u(x,t - σj(t)), (x,t) is a member of the set of Ω × [0, infinity ) equivalent G, where Ω is a bounded domain in Rn with a piecewise smooth boundary partial Ω, and Δ is the Laplacian in Euclidean n-space Rn. © 2001 Elsevier Science Inc.