An independent vertex set of a graph G is a subset of the vertices such that no two vertices in the subset represent an edge of G. Given a vertex cover of a graph, all vertices not in the cover define a independent vertex set. A maximum independent vertex set is an independent vertex set containing the largest possible number of vertices for a given graph. A maximum independent vertex set is not equivalent to a maximal independent vertex set, which is simply an independent vertex set that cannot be extended to a larger independent vertex set. Every maximum independent vertex set is also an independent vertex set, but the converse is not true.