 Nevertheless, Poincaré noted his mistake and introduced in 1905b “representative space” — a physical continuum to which experience proves that it is more convenient to attribute three dimensions — and which may also imply the matching three-dimensionality of  “geometric space,” which is a mathematical continuum, for convenience (Poincaré 1905b: 94; 1913b: 272 — in order to justify his utilization of Lie’s classification. The consequence is that geometry is not independent of any further mathematical space, the structure of which must be presupposed as a primitive notion, contrary to the pragmatically suggested group notion existing in our mind.