  Refining previous work in \cite{Z.3, MaZ.3, Ra, HZ, HR}, we derive sharp
pointwise bounds on behavior of perturbed viscous shock profiles for
large-amplitude Lax or overcompressive type shocks and physical viscosity.
These extend well-known results of Liu \cite{Liu97} obtained by somewhat
different techniques for small-amplitude Lax type shocks and artificial
viscosity, completing a program set out in \cite{ZH}. As pointed out in
\cite{Liu91, Liu97}, the key to obtaining sharp bounds is to take account of
cancellation associated with the property that the solution decays faster along
characteristic than in other directions. Thus, we must here estimate
characteristic derivatives for the entire nonlinear perturbation, rather than
judicially chosen parts as in \cite{Ra, HR}. a requirement that greatly
complicates the analysis.
