PAL Definice Two graphs G1=(V1,E1) and G2=(V2,E2) are isomorphic if there is a bijection f : V1 → V2 such that ∀ x, y ∈ V1 : { f (x), f (y) } ∈ E2 ⇔ { x, y } ∈ E1 The mapping f is said to be an isomorphism between G1 and G2.