The deterministic Traveling Purchaser Problem (TPP) aims at selecting a subset of suppliers, offe... more The deterministic Traveling Purchaser Problem (TPP) aims at selecting a subset of suppliers, offering products at different prices and quantities, so to satisfy a products demand while minimizing traveling and purchasing costs. In this paper, we study a variant of the TPP where both the available quantities and the purchasing prices are uncertain. This more challenging version of the problem, named TPP under uncertainty, allows the purchaser to protect himself against risks of insufficient demand fulfillment and to exploit the benefits of buying at lower price levels. We introduce a two-stage Stochastic Programming formulation of the problem and we present a tailored solution approach based on a Branch-and-Cut method and on a heuristic approach to find initial solutions. Extensive computational experiments show efficiency of the proposed approach in finding the optimal solution of the deterministic equivalent problem
Lecture Notes in Economics and Mathematical Systems, 2009
In transportation service procurement, shipper and carriers cost functions for serving a pair of ... more In transportation service procurement, shipper and carriers cost functions for serving a pair of origin-destination points, usually called lanes, are highly dependent on the opportunity to serve neighboring lanes. Traditional single-item auctions do not allow to capture this type of preferences. On the contrary, they are perfectly modeled in combinatorial auctions where bids on bundles of items are allowed. In
The Enhanced Index Tracking Problem (EITP) calls for the determination of an optimal portfolio of... more The Enhanced Index Tracking Problem (EITP) calls for the determination of an optimal portfolio of assets with the bi-objective of maximizing the excess return of the portfolio above a benchmark and, simultaneously, minimizing the tracking error. The EITP is capturing a growing attention among academics, both for its practical relevance and for the scientific challenges that its study, as a multi-objective problem, poses. Several optimization models have been proposed in the literature, where the tracking error is measured in terms of standard deviation or in linear form using, for instance, the mean absolute deviation. More recently, reward-risk optimization measures, like the Omega ratio, have been adopted for the EITP. On the other side, shortfall or quantile risk measures have nowadays gained an established popularity in a variety of financial applications. In this paper, we propose a class of bi-criteria optimization models for the EITP, where risk is measured using the Weighted...
Lecture Notes in Economics and Mathematical Systems, 2005
The information needed to solve a vehicle routing problem may be not completely known ahead of ti... more The information needed to solve a vehicle routing problem may be not completely known ahead of time. Rather it may be dynamically revealed as time goes on. We consider a dynamic vehicle routing problem faced by a courier company where customer requests with service time windows arrive and have to be serviced on real time by a fleet of vehicles in movement. Differently from other dynamic routing problems motivated by the same courier service, we consider both pick-up and delivery requests and assume that customer requests cannot be refused but can be postponed to future shifts. A heuristic algorithm based on local search is proposed for the problem together with an illustrative example. Experimental analysis is in progress.
The deterministic Traveling Purchaser Problem (TPP) aims at selecting a subset of suppliers, offe... more The deterministic Traveling Purchaser Problem (TPP) aims at selecting a subset of suppliers, offering products at different prices and quantities, so to satisfy a products demand while minimizing traveling and purchasing costs. In this paper, we study a variant of the TPP where both the available quantities and the purchasing prices are uncertain. This more challenging version of the problem, named TPP under uncertainty, allows the purchaser to protect himself against risks of insufficient demand fulfillment and to exploit the benefits of buying at lower price levels. We introduce a two-stage Stochastic Programming formulation of the problem and we present a tailored solution approach based on a Branch-and-Cut method and on a heuristic approach to find initial solutions. Extensive computational experiments show efficiency of the proposed approach in finding the optimal solution of the deterministic equivalent problem
Lecture Notes in Economics and Mathematical Systems, 2009
In transportation service procurement, shipper and carriers cost functions for serving a pair of ... more In transportation service procurement, shipper and carriers cost functions for serving a pair of origin-destination points, usually called lanes, are highly dependent on the opportunity to serve neighboring lanes. Traditional single-item auctions do not allow to capture this type of preferences. On the contrary, they are perfectly modeled in combinatorial auctions where bids on bundles of items are allowed. In
The Enhanced Index Tracking Problem (EITP) calls for the determination of an optimal portfolio of... more The Enhanced Index Tracking Problem (EITP) calls for the determination of an optimal portfolio of assets with the bi-objective of maximizing the excess return of the portfolio above a benchmark and, simultaneously, minimizing the tracking error. The EITP is capturing a growing attention among academics, both for its practical relevance and for the scientific challenges that its study, as a multi-objective problem, poses. Several optimization models have been proposed in the literature, where the tracking error is measured in terms of standard deviation or in linear form using, for instance, the mean absolute deviation. More recently, reward-risk optimization measures, like the Omega ratio, have been adopted for the EITP. On the other side, shortfall or quantile risk measures have nowadays gained an established popularity in a variety of financial applications. In this paper, we propose a class of bi-criteria optimization models for the EITP, where risk is measured using the Weighted...
Lecture Notes in Economics and Mathematical Systems, 2005
The information needed to solve a vehicle routing problem may be not completely known ahead of ti... more The information needed to solve a vehicle routing problem may be not completely known ahead of time. Rather it may be dynamically revealed as time goes on. We consider a dynamic vehicle routing problem faced by a courier company where customer requests with service time windows arrive and have to be serviced on real time by a fleet of vehicles in movement. Differently from other dynamic routing problems motivated by the same courier service, we consider both pick-up and delivery requests and assume that customer requests cannot be refused but can be postponed to future shifts. A heuristic algorithm based on local search is proposed for the problem together with an illustrative example. Experimental analysis is in progress.
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Papers by R. Mansini