An irredundant set of vertices V V in a graph G = (V; E) has the property that for every vertex u V ; N[V - {u}] is a proper subset of N[V ]. We investigate the parameterized complexity of determining whether a graph has an irredundant set of size k, where k is the parameter. The interest of this problem is that while most "k-element vertex set" problems are NP-complete, several are known to be
Rodney G. Downey, Michael R. Fellows, Venkatesh Ra