“…For example, the edge cut of connected component 2 in Fig. 4(1) includes eleven edges, namely: (3,2), (3,4), (3,6), (3,8), (7, 2), (7, 4) (7, 6) (7, 8) (7,10) (7, 11) (7,12). δ(S) is used to denote the edge cut set of S; x m (δ(S)) is to add up the road type variable (0/1) associated with each edge in δ(S) .…”