2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/161284We investigate the condition under which the Eulerian trail of a digraph is unique, and design a finite automaton to examine it. The algorithm is effective, for if the condition is violated, it will be noticed immediately without the need to trace through the whole trail.Computational ComplexityLogic in Computer ScienceF.4.3text