  In this paper, we would like to derive three-ball inequalities and
propagation of smallness for the complex second order elliptic equation with
discontinuous Lipschitz coefficients. As an application of such estimates, we
study the size estimate problem by one pair of Cauchy data on the boundary. The
main ingredient in the derivation of three-ball inequalities and propagation of
smallness is a local Carleman proved in our recent paper [FVW].
