The traveling salesman problem on a graph and some related integer polyhedra

TLDR: Some facet inducing inequalities of the convex hull of the solutions to the Graphical Traveling Salesman Problem are given and the so-called comb inequalities of Grötschel and Padberg are generalized.

Abstract: Given a graphG = (N, E) and a length functionl: E → ℝ, the Graphical Traveling Salesman Problem is that of finding a minimum length cycle goingat least once through each node ofG. This formulation has advantages over the traditional formulation where each node must be visited exactly once. We give some facet inducing inequalities of the convex hull of the solutions to that problem. In particular, the so-called comb inequalities of Grotschel and Padberg are generalized. Some related integer polyhedra are also investigated. Finally, an efficient algorithm is given whenG is a series-parallel graph.