Oscillation for systems of parabolic equations of neutral type (Q1964729)

Sufficient conditions for the oscillation of the following system of parabolic differential equations of neutral type are obtained \[ {\partial\over\partial t}\left[b(t)u_i(x,t)- \sum_{s=1}^r\lambda_s(t)u_i(x,t-\tau_s)\right]= a_i(t)\Delta u_i(x,t) \] \[ +\sum_{j=1}^d a_{ij}\Delta u_i(x,\rho_j(t)) -\sum_{k=1}^m\sum_{h=1}^l q_{ikh}(x,t) u_k(x,\sigma_h(t)), \] \[ (x,t)\in\Omega\times[0,\infty),\quad i=1,2,\dots,m, \] where \(\Omega\) is a bounded domain in \(\mathbb{R}^n\) and \(\Delta\) is the Laplace operator with respect to the spatial variables. The results are illustrated with examples.