Bulk quartic vertices from boundary four-point correlators
  We present arguments which suggest that the bulk higher-spin gravity duals of weakly-coupled conformal field theories obey some refined notion of locality. In particular, we discuss the Mellin amplitude programme in this context. We focus on the $O(N)$ vector model and minimal higher-spin gravity as a paradigmatic example of such holographic dual pairs. We restrict ourselves to three- and four-point functions of scalar primary operators, but the qualitative conclusions are expected to hold for the generic case. 
Xavier Bekaert, Johanna Erdmenger, Dmitry Ponomarev and Charlotte   Sleight
hep-th