Oscillation properties for systems of hyperbolic differential equations ofneutral type

Sufficient conditions are established for the oscillations of systems of hy perbolic differential equations of the form partial derivative(2)/partial derivative t(2)(p(t)u(i)(x, t) + Sigma(r=1)(d ) lambda(r)(t)u(i)(x, t-tau(r))) = a(i)(t)Delta u(i)(x, t) + Sigma(j=1)(m) Sigma(k=1)(s) a(ijk) (t)Delta u(j )(x, rho(k)(t)) -q(i)(x, t)u(i)(x, t) - Sigma(j=1)(m) Sigma(h=1)(l) q(ijh)(x,t)u(j)(x, sigm a(h)(t)), (x, t) is an element of Omega x [0, infinity) = G, i = 1, 2, ..., m, where Omega is a bounded domain in R-n with a piecewise smooth boundary par tial derivative Omega, and Delta is the Laplacian in Euclidean n-space R-n. (C) 2000 Academic Press.