2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/93941Suppose we are given two graphs on $n$ vertices. We define an observable in the Hilbert space $\Co[(S_n \wr S_2)^m]$ which returns the answer ``yes'' with certainty if the graphs are isomorphic and ``no'' with probability at least $1-n!/2^m$ if the graphs are not isomorphic. We do not know if this observable is efficiently implementable.5 pages, no figuresQuantum Physicstext