Let's define a new problem HUB:
• Input: An undirected graph G = (V, E) and a positive integer k.
• Output: TRUE if there is a vertex, v ? V, such that there is an edge from
v to at least k other vertices and no pair of those k vertices are connected
by an edge.
Being able to identify hubs in graphs would be useful in real life problems but,
unfortunately, we will see the problem is NP-hard.
(1) Which of the following graphs contain a HUB for k = 5.