a University of Jyväskylä, Department of Mathematics and Statistics, PL 35, FIN-40351, Jyväskylä, Finlandf1vmho@cc.jyu.fif1
b “Al. I. Cuza” University, Faculty of Mathematics, B-dul Carol I, 11, RO-6600, Ia?i, Romaniaf2gmoro@uaic.rof2
Abstract:
The regularity of the solution of the telegraph system with nonlinear monotone boundary conditions is investigated by two methods. The first one is based on D'Alembert-type representation formulae for the solution. In the second method the telegraph system is reduced to a linear Cauchy problem with a locally Lipschitzian functional perturbation; then regularity results are established by appealing to the theory of linear semigroups.