directed graph

인트로.

lUndirected Graphs are not adequate for representing several situations
undirected graph 에서는 몇가지 상황을 나타내기엔 충분하지 않다.

lin the graph representation traffic network where an edge may represent a street 
 그래프에서 edge가 교통망의 거리를 나타낸다.

lWe have to assign directions to the edges to indicate the permissible direction of traffic flow 
 traffic flow의 허용방향을 표시하려면 edge들로 방향을 할당해야 한다.


 Basic Definitions and Concept
 rDirected Graph G

    lG = (V, E )

    lFinite set V  of elements called vertices

   lUse Symbols (v1, v2, v3 …)

    lFinite set E  of elements called edge

   lUse Symbols (e1, e2, e3 …)

    lel=(vi,vj)

   lVi, Vj = end vertices

   lVi = initial vertex

   lVj = terminal vertex