“…The use of graph theory to classify dynamical systems is typical in two and three dimensions. The topological classifications of flows were obtained on closed 2-manifolds in [7,16,19,20,21,38,1,27,30,42,28,29,36,26], and on 2-manifolds with the boundary in [5,8,17,30,27,24,35,21,36]. Complete topological invariants of Morse-Smale flows on 3-manifolds was constructed in [43,45,34,23,25,10,4,3].…”