Structural Models: An Introduction to the Theory of Directed Graphs

3-connected acyclic digraph assignment balanced basic basis block called chapter Clearly communication complete concept connectedness consider consists construct contains converse Corollary corresponding cost cut point cycle cyclic definition digraph D digraph of Figure directional disconnected discussion distance distinct empirical entry equal equivalent exactly example given gives Hence illustrated Implies indegree indicate integer joining kinds least length line basis matrix means number of lines obtained origin outdegree pair of points path person point basis positive possible presented proof properties prove reach reachable receiver relation removal represent result S₁ satisfies semicycle semipath semipath joining sequence shown in Figure signed digraph statement strictly strong component strong digraph structure subgraph symmetric Theorem theory tournament transitive transmitter triples unilateral unique v₁ v₂ weak component weak digraph weakening