Graph equation

In graph theory, Graph equations are equations in which the unknowns are graphs.

One of the central questions of graph theory concerns the notion of isomorphism.

(i.e., graph isomorphism) The graphs in question may be expressed differently in terms of graph equations.

For example, G = K3, and H = K2 are the solutions of the graph equation L(K3) = T(K2) and G = K4, and H = K3 are the solutions of the graph equation L(K4) = T(K3).

Note that T(K3) is a 4-regular graph on 6 vertices.