Global existence for coupled reaction-diffusion systems

We prove here global existence in time of classical solutions for reaction-diffusion systems with strong coupling in the diffusion and with natural structure conditions on the nonlinear reactive terms. This extends some similar results in the case of a diagonal diffusion-operator associated with nonlinearities preserving the positivity and the total mass of the solutions or for which the total mass is a priori bounded. Here, however, no positivity assumption is made since nondiagonal systems do not preserve it. (C) 2000 Academic Press.