ABSTRACT
Formally, a graph G = (V, E) is an ordered pair of a set of vertices V = {vi} and a set of edges E ⊆ V × V [BM76, Wes01]. Graphs are abstract constructs that can model relationships (edges) between entities (vertices). The edge (ui, uj) connecting vertices ui and uj is incident to ui and uj and signifies that vertex ui is adjacent to uj . The graph is called undirected , if (vi, vj) ∈ E implies (vj , vi) ∈ E . If the order of the vertices in an edge (source-sink) is important, then the graph is called directed (or digraph).
