  An exact correspondence is pointed out between conformal field theories in D
dimensions and dual resonance models in D' dimensions, where D' may differ from
D. Dual resonance models, pioneered by Veneziano, were forerunners of string
theory. The analog of scattering amplitudes are called Mellin amplitudes; they
depend on complex variables which substitute for the Mandelstam variables on
which scattering amplitudes depend. The Mellin amplitudes satisfy exact duality
- i.e. meromorphy with simple poles in single variables, and crossing symmetry
- and an appropriate form of factorization which is implied by operator product
expansions (OPE). Duality is a D-independent property. The positions of the
leading poles are given by the dimensions of fields in the OPE; their residues
depend on D and determine satellites. Dimensional reduction and induction D
goes to D-1 and D+1 are discussed. Dimensional reduction leads to the
appearence of Anti de Sitter space.
