2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/90550We give a characterization of the line digraph of a regular digraph. We make use of the characterization, to show that the underlying digraph of a coined quantum random walk is a line digraph. We remark the connection between line digraphs and in-split graphs in symbolic dynamics.11 pagesQuantum Physicstext