Multiple edges are two or more edges connecting the same two vertices within a multigraph. Multiple edges of degree d_(i j) between vertex i and vertex j correspond to an integer d_(i j)>1 as the (i, j) entry of the incidence matrix of the multigraph. A diagonal entry d_(k k)>0 corresponds to a single or multiple loop. Integers d_(i j)>1 can similarly correspond to multiple edges in a directed multigraph.

graph loop | hypergraph | Königsberg bridge problem | multigraph | pseudograph