Constrained spanning trees and the traveling salesman problem (Q1823163)

Since the travelling salesman problem is very difficult to solve, it is of importance to find a good lower bound for the optimal value. A common method to bound the optimal value makes use of 1-trees. In this paper the authors strengthen this bound by imposing degree-constraints upon the 1- trees. This is achieved by choosing vertices for the constraints from a stable set containing 1. Computation of bounds is done using subgradient optimization. Computational results are presented.