The Steiner Tree Problem II: Properties and Classes of Facets, Mathematical Programming
This is the second part of two papers addressing the study of the facial structure of the Steiner tree polyhedron. In this paper we identify several classes of facet defining inequalities and relate them to special classes of graphs on which the Steiner tree problem is known to be NP-hard.
Sunil Chopra, M. R. Rao
Chopra, Sunil, and M. R. Rao. 1994. The Steiner Tree Problem II: Properties and Classes of Facets. Mathematical Programming. 64(1-3): 231-246.