Graph, undirected graph, nonoriented graph
Graph, undirected graph, nonoriented graph --- граф, неориентированный граф.
A graph consists of a finite set of vertices or nodes , a finite set of edges , and a mapping from to assigning to each edge two, not necessarily distinct, vertices of (the extremities of ). The graph will be denoted by or simply . It is easy to see that an edge corresponds to an undirected pair of vertices. If we consider ordered pairs of vertices , we say about a directed graph with the set of arcs .