  The purpose of this paper is to present a universal approach to the study of
controllability/observability problems for infinite dimensional systems
governed by some stochastic/deterministic partial differential equations. The
crucial analytic tool is a class of fundamental weighted identities for
stochastic/deterministic partial differential operators, via which one can
derive the desired global Carleman estimates. This method can also give a
unified treatment of the stabilization, global unique continuation, and inverse
problems for some stochastic/deterministic partial differential equations.
