When entering a horizontal logistics alliance, companies can expect a significant cost decrease. In this paper, we show that when the partners in an alliance adopt a flexible attitude (i.e. allow changes to the terms of their deliveries), the total cost can be further decreased. We argue that the method used to allocate the total cost to the different partners should therefore encourage such flexibility. A case study of three companies in Belgium achieves a 25.83% decrease in transportation costs. Allocating this collaborative gain with the Shapley value, the individual gains range from 19.01% to 37.56%. By allowing changes to delivery dates and allowing large orders to be split into several deliveries, the partners in the alliance can increase the collaborative gain and their individual gains. The Shapley value is found to encourage flexibility.

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Scope and Purpose. Tabu Search (TS) and Simulated Annealing (SA) have demonstrated to be appropriate metaheuristics for solving NP-hard combinatorial optimization problems, such as the Vehicle Routing Problem with side-constraints. In order to compare the performances of both metaheuristics with each other and with a traditional descent implementation, a comparison of the best solution independent of computing times is fundamentally wrong because metaheuristics have no unambiguous stopping criteria, as opposed to traditional descent implementations.

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A reply to Peter Quarrell:The purpose of our article was to illustrate that the simulation software market can be segmented into several clusters oriented towards different kinds of users.We are not unaware of HOCUS's existence» as Peter Quarrell suggests, just as we are not unaware of the existence of the other 227 simulation software packages also mentioned in the "Catalog of simulation software' (Simulation, October 1988). Our sample was primarily based on this list. We included 15 packages satisfying the following conditions: it must be (more-or-less) general-purpose simulation software; it must be able to handle (at least) discrete-event simulations; it had to be available at that time under the DOS operating system for the IBM PC and compatibles; 25 we must have received sufficient objective information concerning the package for inclusion in the final report.Of the many packages we did not include, HOCUS had been left out early in the study because of the DOS constraint: as indicated in Simulation (October 1988, p. 143), HOCUS was available on lBMs and compatibles only under the Xenix/Unix operating system. We apologise to all manufacturers of simulation software who have been left out, but we do not think that this should affect the basic idea and result of our study "Segmenting the simulation software market".