
Data Organization ◾ 209
by a set of features that describe the overall structure of the graph itself.
For our text, the features of most concern are listed next and illustrated by
reference to graph G of Figure7.13.
• Adjacency—Assume that U and V are vertices in some graph. Vertex U
is adjacent to vertex V if there is an arc (U, V) in the graph. For exam-
ple, vertex D is adjacent to vertex C in G since the arc (D, C) appears in
G. Vertex C is not adjacent to D since the arc (C, D) is not in G.
• Loop—A loop is any arc such that the rst and second nodes of the
arc are the same. Graph G does not have a loop.
• In-degree—e in-degree ...