There is an underlying undirected graph G = (V, E) with weights on the vertices, where the weight on vertex v is denoted by wv = d(v) (the degree of the vertex). Your goal is to find a vertex cover set U (a set where for every e = (u, v), one of vertices u, v is in U ) with the minimal total weight possible. Show that any greedy algorithm, gives a 2-approximation to the best vertex cover.