Usual retail store facility location models asume that each consumer travels to a store, purchases a product and goes back to his or her origin point. We present location models in which we consider that consumers can make trips that include more than a stop. These stops can be either for purchasing more than one product, or for performing comparison-shopping, i.e., comparing two (or more) different mutual substitute products before making the decision on which product is better fit to his needs and taste and make the purchase, or whether not to purchase at all.
In both cases, the problem can be cast as a bi-level programming problem, but we reformulate it as a one level, linear integer programming model.
Computational experience is presented using exact and heuristic approaches.