2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/145756We give a family of counter examples showing that the two sequences of polytopes $Φ_{n,n}$ and $Ψ_{n,n}$ are different. These polytopes were defined recently by S. Friedland in an attempt at a polynomial time algorithm for graph isomorphism.Computational ComplexityDiscrete Mathematicstext