9 Given a graph G(V, E), a subset V, of V (V, is incident on one or more vertices in V'. That is, if (u, v) e E, then u eV" or v e V" or both. For example, in the following graph, b, d, e.f, g is a vertex cover. V) is called vertex cover if every edge 2 (a) Find a vertex cover V' in the above graph such that V'has at most 4 vertices (b) Prove that, if V" is an independent set, then V-V" is a vertex cover and vice versa