2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147705It is shown that $N^2$ is the upper limit for the number of histories in a decohering family of $N$-state quantum system. Simple criterion is found for a family of $N^2$ fine grained decohering histories of Gell-Mann and Hartle to be identical with a family of Griffiths' consistent quantum trajectories.5 pages LaTeX (2nd version, new ref. included)General Relativity and Quantum Cosmologytext