notes figure directed graph the direction is indicated by an arrow the set of vertices for this graph remains the same as that of the graph in the earlier examplei ( ( , , , , however the set of edges would be ( {( , )( , )( , )( , )( , )( , )( , )do you notice the differencenote arrow is always from tail vertex to head vertex in our further discussion on graphswe would refer to directed graph as digraph and undirected graph as graph basic graph terminology good deal of nomenclature is associated with graphs most of the terms have straight foward definitionsand it is convenient to put them in one place even though we would not be using some of them until later adjacent vertices vertex is said to be adjacent to vertex if there is an edge ( or ( figure vertices adjacent to node are , , and and that to node are and lovely professional university