is mentioned by

Def G H == vmap:(Vertices(G)Vertices(H)), emap:(Edges(G)Edges(H)). Bij(Vertices(G); Vertices(H); vmap) & Bij(Edges(G); Edges(H); emap) & (vmap,vmap) o Incidence(G) = Incidence(H) o emap

[graph-isomorphic]

In prior sections: graph 1 1

Try larger context: Graphs