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Input from QCD and string theory is used in order to elucidate basic features of the string theory dual of QCD, It is argued that the relevant string theory is a fivedimensional version of the type0 superstring. The vacuum solution is asymptotically AdS5, and the geometry near the boundary is stringy. The structure of YM perturbation theory however emerges near the boundary. In the IR, the theory is argued to be wellapproximated by a twoderivative truncation that takes into account strong coupling effects. This explains the success of previously proposed fivedimensional Eisteindilaton gravity with an appropriate potential to describe salient features of the strong YM dynamics. [ABSTRACT FROM AUTHOR]

The question of graviton cloning in the context of the bulk/boundary correspondence is considered. It is shown that multi-graviton theories can be obtained from products of large-N CFTs. No more than one interacting massless graviton is possible. There can be however, many interacting massive gravitons that can be arbitrarily light. This is achieved by coupling CFTs via multi-trace marginal or relevant perturbations. The geometrical structure of the gravitational duals of such theories is that of product manifolds with their boundaries identified. The interpretation of such theories is discussed. Potential applications to massive gravity and cosmology are briefly suggested. [ABSTRACT FROM AUTHOR]