  We give a group-theoretic interpretation of relativistic holography as
equivalence between representations of the anti de Sitter algebra describing
bulk fields and boundary fields. Our main result is the explicit construction
of the boundary-to-bulk operators for arbitrary integer spin the framework of
representation theory. Further we show that these operators and the
bulk-to-boundary operators are intertwining operators. In analogy to the de
Sitter case, we show that each bulk field has two boundary (shadow) fields with
conjugated conformal weights. These fields are related by another intertwining
operator given by a two-point function on the boundary.
