36Undirect = 0, // A graph in which edges have no orientation.
37Direct = 1, // A directed graph or digraph is an ordered pair D = (V, A)
38Mixed = 2, // A mixed graph G is a graph in which some edges may be directed and some may be undirected.
39Multi = 3, // The term "multigraph" is generally understood to mean that multiple edges (and sometimes loops) are allowed.
40Simple = 4, // As opposed to a multigraph, a simple graph is an undirected graph that has no loops and no more than one edge between any two different vertices.
41Weighted = 5, // A graph is a weighted graph if a number (weight) is assigned to each edge.
42HalfEdges = 6 // In exceptional situations it is even necessary to have edges with only one end.