“…The action of Γ n on boolean FDS was first introduced by L.Glass [5] for the classification of asynchronous STG.In [22,2], this action is studied with symbolical considerations, and the authors note that isometric STG are also isomorphic (in the sense of graph theory, renumbering of the nodes preserving adjacency). In Proposition 2 we emphasize a class of dynamics for which isomorphic STG are also isometric.…”