  In this paper, we introduce a new combinatorial curvature on triangulated
surfaces with inversive distance circle packing metrics. Then we prove that
this combinatorial curvature has global rigidity. To study the Yamabe problem
of the new curvature, we introduce a combinatorial Ricci flow, along which the
curvature evolves almost in the same way as that of scalar curvature along the
surface Ricci flow obtained by Hamilton \cite{Ham1}. Then we study the long
time behavior of the combinatorial Ricci flow and obtain that the existence of
a constant curvature metric is equivalent to the convergence of the flow on
triangulated surfaces with nonpositive Euler number. We further generalize the
combinatorial curvature to $\alpha$-curvature and prove that it is also
globally rigid, which is in fact a generalized Bower-Stephenson conjecture
\cite{BS}. We also use the combinatorial Ricci flow to study the corresponding
$\alpha$-Yamabe problem.
