“…Coullard et al [32,33] studied the Steiner 2-node connected subgraph problem, that is, the NSDNP where r ∈ {0, 2} V . In [32], they gave a linear time algorithm for the Steiner 2-node connected subgraph problem on Halin graphs and on graphs noncontractible to W 4 , the latter being the graphs that do not reduce to W 4 (i.e., the wheel on five nodes) by means of deletions and contractions of edges. They also described, in [33], the dominant of the polytope LNSDP (G, r) where G is a graph noncontractible to W 4 and r ∈ {0, 2} V .…”