Two graphs G_1 = (V_1, E1) and G_2 = (V_2, E_2) such that V_1 = v_2 = {1, 2, ..., n} are isomorphic if there is a one-one, onto function pi: {1, 2, ..., n} rightarrow (1, 2, ...., n} such that for every i, j Elementof {1, 2, ..., n} (i, j) elementof E_1 doubleheadarrow (pi (i), pi (j)) elementof E_2 Show that the following decision problem in in NP Problem: Isomorphism Input Instance: Two graphs G_1 = (V_1, E_1) and G2 = (V_2, E_2) where V_1 = V_2 = {1, 2, ..., n} Decision: Are G_1 and G_2 isomorphic