Das Lemma von Max Müller-Nagumo-Westphal für stark gekoppelte Systeme parabolischer Funktional-Differentialgleichungen.
We study the Dirichlet boundary value problem for eikonal type equations of ray light propagation in an inhomogeneous medium with discontinuous refraction index. We prove a comparison principle that allows us to obtain existence and uniqueness of a continuous viscosity solution when the Lie algebra generated by the coefficients satisfies a Hörmander type condition. We require the refraction index to be piecewise continuous across Lipschitz hypersurfaces. The results characterize the value...
Two new time-dependent versions of div-curl results in a bounded domain are presented. We study a limit of the product , where the sequences and belong to . In Theorem 2.1 we assume that is bounded in the -norm and is controlled in the -norm. In Theorem 2.2 we suppose that is bounded in the -norm and is controlled in the -norm. The time derivative of is bounded in both cases in the norm of . The convergence (in the sense of distributions) of to the product of weak limits...