Got results with DiGraph.girth() which appear inconsistent to me. girth() returns 3 and powers of the adjacency matrix suggest there are no directed triangle cycles and couldn't s see a directed triangle cycle on the plot of the digraph.
sage: GR=DiGraph('FWE@_WF@o?');M=GR.adjacency_matrix() sage: GR.girth() 3 sage: (M^3).trace() 0 sage: GR Digraph on 7 vertices -- You received this message because you are subscribed to the Google Groups "sage-support" group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.