We consider the P2P orienteering problem on general metrics and present a (2+ε) approximation algorithm. In the stochastic P2P orienteering problem we are given a metric and each node has a fixed reward and random size. The goal is to devise a strategy for visiting the nodes so as to maximize the expected value of the reward without violating the budget constraints. We present an approximation ...

We address a variant of the vehicle routing problem with time windows, which includes the decision of how many deliverymen should be assigned to each vehicle in addition to the usual routing and scheduling decisions. This variant is relevant in cases in which many requests should be delivered in busy urban areas on the same day, and the service times at customers are long in relation to vehicle...

In this thesis we study online optimization problems in routing and scheduling. An online problem is one where the problem instance is revealed incrementally. Decisions can (and sometimes must) be made before all information is available. We design and analyze (polynomial-time) online algorithms for a variety of problems. We utilize worst-case competitive ratio (and relaxations thereof), asympt...

Vehicle Routing Problem (VRP) is addressed to a class of problems for determining a set of vehicle routes, in which each vehicle departs from a given depot, serves a given set of customers, and returns back to the same depot. On the other hand, simultaneous delivery and pickup problems have drawn much attention in the past few years due to its high usage in real world cases. This study, therefo...

For this paper, we explored the implementation of the cuckoo search algorithm applied to the capacitated vehicle routing problem. The cuckoo search algorithm was implemented with Lévy flights with the 2-opt and double-bridge operations, and with 500 iterations for each run. The algorithm was tested on the problem instances from the Augerat benchmark dataset. The algorithm did not perform well o...

In this work we consider the generalized vehicle routing problem with stochastic demands (GVRPSD). This NP-hard problem combines the clustering aspect of the generalized vehicle routing problem with the uncertainty aspect of the vehicle routing problem with stochastic demands. We propose an integer L-shaped method based on decomposition and branch-and-cut. The subproblem of computing the restoc...

The Vehicle Routing Problem with TimeWindows (VRPTW) consists in determining the routing plan of vehicles with identical capacity in order to supply the demands of a set of customers with predefined time windows. This complex multi-constrained problem has been widely studied due to its industrial, economic and environmental implications. In this work, we are interested in defining the number of...

We consider a combination of the capacitated vehicle routing problem and a class of additional loading constraints involving a parallel machine scheduling problem. The work is motivated by a real-world transportation problem occurring to a wood-products retailer, which delivers its products to a number of customers in a specific region. We solve the problem by means of two different metaheurist...