The term multigraph refers to a graph in which multiple edges between nodes are either permitted or required (Skiena 1990, p. 89, Pemmaraju and Skiena 2003, p. 198; Zwillinger 2003, p. 220). West (2000, p. xiv) recommends avoiding the term altogether on the grounds of this ambiguity. Some references require that multigraphs possess no graph loops, some explicitly allow them (Hartsfield and Ringel 1994, p. 7; Cormen et al. 2001, p. 89), and yet others do not include any explicit allowance or disallowance. Worse still, Tutte uses the term "multigraph" to mean a graph containing either loops or multiple edges.

edge multiplicity | graph loop | graph multiplicity | hypergraph | Königsberg bridge problem | mixed graph | multiple edge | pseudograph | simple graph