AdS gravity, SO(2,d) gauge theory and Holography

Inspired by the general relation between the boundary global symmetry and the bulk gauge symmetry in AdS/CFT, we reformulate the $d+1$ dimensional AdS gravity theory as a $SO(2,d)$ gauge theory. In this formalism, the pull back of the bulk equation of motion onto a co-dimension one hypersurface $\Sigma$ can be naturally related to the $SO(2,d)$ conservation law under a local energy scale in the dual CFT. The consistency of CFT requires that the $SO(2,d)$ covariant anomaly vanishes at arbitrary scale. After imposing a covariant area law as the renormalization condition, the vanishing of $SO(2,d)$ anomaly implies that the dual bulk geometries must satisfy the Einstein equation.