A. Langevin et al., A 2-COMMODITY FLOW FORMULATION FOR THE TRAVELING SALESMAN AND THE MAKESPAN PROBLEMS WITH TIME WINDOWS, Networks, 23(7), 1993, pp. 631-640
We present a new two-commodity flow formulation for the traveling sale
sman problem. Each commodity corresponds to a resource that is either
distributed or picked up along the tour of all nodes. This formulation
is partcularly well suited to handling time window constraints; the r
esource used is then the time. This formulation can be extended to the
makespan problem. For a n-node problem, the linear relaxation of the
formulation involves only O(n) constraints and O(n2)variables. Impleme
ntation issues are discussed and numerical experimentations have been
realized for problems of up to 60 nodes. (C) 1993 by John Wiley & Sons
, Inc.