Multigraph

A graph in which multiple edges are allowed.

Comments

Multigraphs are very useful for modelling the molecular structure of chemical compounds, see [a1]. Multigraphs in which loops are also allowed (called pseudo-graphs in [a2]) are called graphs by the Canadian School of graph-theorists (see [a3]). See also Graph.

References

[a1]	A.T. Balaban (ed.) , Chemical application of graph theory , Acad. Press (1976)
[a2]	F. Harary, "Graph theory" , Addison-Wesley (1969) pp. Chapt. 9
[a3]	J.A. Bondy, U.S.R. Murthy, "Graph theory with applications" , Macmillan (1976)