2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/194753The conformal extensions of three kinds of special relativity with ISO(1,3)/SO(1,4)/SO(2,3) invariance on Mink/dS/AdS space, respectively, are realized on an SO(2,4)/Z_2 invariant projective null cone [N] as the (projective) boundary of the 5-d AdS-space. The relations among the conformal Mink/dS/AdS spaces, the motions of light signals and the conformal field theories on them can be given. Thus, there should be a triality for these conformal issues and the conjectured AdS/CFT correspondence.10 pages, no figures, revtex4High Energy Physics - Theorytext