De Sitter Relativity and Cosmological Principle

The formalism of Fantappie-Arcidiacono Projective General Relativity - also known as De Sitter Relativity - has recently been revised in order to make possible cosmological models with expansion, similarly to ordinary Fridman cosmology formulated within the context of General Relativity. In this article, several consequences of interest in the current cosmological debate are examined and discussed in a semiquantitative manner. Specifically: re-examination of the Supernova Project results using this new formalism, with a new estimate of the cosmological parameters; the ordinary matter to dark matter densities ratio; the existence of a new fundamental constant having the dimensions of an acceleration and its relation with dark matter.