Strong unique continuation results for differential inequalities

The main result of this paper is a strong uniqueness theorem for differential inequalities of the form \triangle u(x)\ less than or equal to \V(x) u(x)\ + \W(x) del u(x)\, where V and W are radial functions in L-loc(n/2) (Omega) and L-loc(n) (Omega) respectively, and Omega is a connected open subset of R-n. Other results involving other spaces of potentials V and W are proved. Our method relies on sharp Carleman estimates. (C) 1997 Academic Press.