Quantum Fields in anti-de Sitter space and the Maldacena conjecture
  We review in this lecture the relation between the Maldacena Conjecture, also known as AdS/CFT correspondence, and the so called Holographic principle that seems to be an essential ingredient for a quantum gravity theory. We also illustrate the idea of Holography by showing that the curvature of the anti-de Sitter space reduces the number of degrees of freedom making it possible to find a mapping between a quantum theory defined on the bulk and another defined on the corresponding boundary. 
Nelson R. F. Braga