2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34775Space-time coordinates in DSR theories with two invariant scales based on a dispersion relation with an energy independent speed of light are introduced by the demand, that boost and rotation generators are invariant under a transformation from SR to DSR variables. This turns out to be equivalent to a recent suggestion postulating the existence of plane wave solutions in DSR theories. The momentum space representation of coordinates is derived, yielding a noncommutative space-time and the deformed algebra.5 pages, no figuresGeneral Relativity and Quantum Cosmologytext