What is the definition of a graph??
Definitions Definitions in graph theory vary. The following are some of the more basic ways of defining graphs and related mathematical structures. Graph A general example of a graph (actually, a pseudograph) with three vertices and six edges.In the most common sense of the term,[1] a graph is an ordered pair G: = (V,E) comprising a set V of vertices or nodes together with a set E of edges or lines, which are 2-element subsets of V. To avoid ambiguity, this type of graph may be described precisely as undirected and simple. Other senses of graph stem from different conceptions of the edge set. In one more generalized notion,[2] E is a set together with a relation of incidence that associates with each edge two vertices. In another generalized notion, E is a multiset of unordered pairs of (not necessarily distinct) vertices. Many authors call this type of object a multigraph or pseudograph. All of these variants and others are described more fully below. The vertices belonging to an edge
