Phragmén-Lindelöf type theorems for a system of nonhomogeneous equations
Kuang-Ho Chen · Pacific Journal of Mathematics · 1974
Hyperbolic systems of N equations are considered (1) duldt=P(D)u+f(x, t), with u in R N and (x, t) in R n xR x ,For t = 0, then u^x) =f(x, 0).Differentiating both sides of the r relations implies that for i = 2, , r + 1,