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Pla A.,University of Girona | Lopez B.,University of Girona | Murillo J.,Newronia | Maudet N.,University Pierre and Marie Curie
Expert Systems with Applications | Year: 2014

Multi-attribute auctions allow agents to sell and purchase goods and services taking into account more attributes than just price (e.g. service time, tolerances, qualities, etc.). In this paper we analyze attributes involved during the auction process and propose to classify them between verifiable attributes, unverifiable attributes and auctioneer provided attributes. According to this classification we present VMA2, a new Vickrey-based reverse multi-attribute auction mechanism, which takes into account the different types of attributes involved in the auction and allows the auction customization in order to suit the auctioneer needs. On the one hand, the use of auctioneer provided attributes enables the inclusion of different auction concepts, such as social welfare, trust or robustness whilst, on the other hand, the use of verifiable attributes guarantee truthful bidding. The paper exemplifies the behavior of VMA2 describing how an egalitarian allocation can be achieved. The mechanism is then tested in a simulated manufacturing environment and compared with other existing auction allocation methods. © 2014 Elsevier Ltd. All rights reserved.


Bofill M.,University of Girona | Busquets D.,Imperial College London | Munoz V.,Newronia | Villaret M.,University of Girona
Constraints | Year: 2013

The presence of uncertainty in the real world makes robustness a desirable property of solutions to constraint satisfaction problems (CSP). A solution is said to be robust if it can be easily repaired when unexpected events happen. This issue has already been addressed in the frameworks of Boolean satisfiability (SAT) and Constraint Programming (CP). Most existing works on robustness implement search algorithms to look for robust solutions instead of taking the declarative approach of reformulation, since reformulation tends to generate prohibitively large formulas, especially in the CP setting. In this paper we consider the unaddressed problem of robustness in weighted MaxSAT, by showing how robust solutions to weighted MaxSAT instances can be effectively obtained via reformulation into pseudo-Boolean formulae. Our encoding provides a reasonable balance between increase in size and performance, as shown by our experiments in the robust resource allocation framework. We also address the problem of flexible robustness, where some of the breakages may be left unrepaired if a totally robust solution does not exist. In a sense, since the use of SAT and MaxSAT encodings for solving CSP has been gaining wide acceptance in recent years, we provide an easy-to-implement new method for achieving robustness in combinatorial optimization problems. © 2012 Springer Science+Business Media New York.


Torrent-Fontbona F.,University of Girona | Munoz V.,Newronia | Lopez B.,University of Girona
Expert Systems with Applications | Year: 2013

Immobile Location-Allocation (ILA) is a combinatorial problem which consists in, given a set of facilities and a set of demand points, determining the optimal service each facility has to offer and allocating the demand to such facilities. The applicability of optimization methods is tied up to the dimensionality of the problem, but since the distance between data points is a key factor, clustering techniques to partition the data space can be applied, converting the large initial problem into several simpler ILA problems that can be solved separately. This paper presents a novel method that combines clustering and heuristic methods to solve an ILA problem, which reduces the elapsed time keeping the quality of the solution found compared with other heuristics methods. © 2013 Elsevier Ltd. All rights reserved.


Pla A.,University of Girona | Lopez B.,University of Girona | Murillo J.,Newronia
Frontiers in Artificial Intelligence and Applications | Year: 2013

Demonstrating the incentive compatibility of an auction mechanism is always a hard but essential work in auction mechanism design. In this paper we discuss three different approaches to proof or check such property in regard of a multi-attribute auction mechanism: by analyzing well-known sufficient conditions, by mathematical analyzing the rules that govern the mechanism, and by empirically checking the mechanism. Particularly, for dealing with the second approach, we propose a new method which consists on seeking for a counterexample with a constraint solver. © 2013 The authors and IOS Press. All rights reserved.


Pla A.,University of Girona | Lopez B.,University of Girona | Murillo J.,Newronia
Knowledge-Based Systems | Year: 2015

Multi-attribute resource allocation problems involve the allocation of resources on the basis of several attributes, therefore, the definition of a fairness method for this kind of auctions should be formulated from a multi-dimensional perspective. Under such point of view, fairness should take into account all the attributes involved in the allocation problem, since focusing on just a single attribute may compromise the allocations regarding the remainder attributes (e.g. incurring in delayed or bad quality tasks). In this paper, we present a multi-dimensional fairness approach based on priorities. For that purpose, a recurrent auction scenario is assumed, in which the auctioneer keeps track of winner and losers. From that information, the priority methods are defined based on the lost auctions number, the number of consecutive loses, and the fitness of their loser bids. Moreover, some methods contain a probabilistic parameter that enables handling wealth ranking disorders due to fairness. We test our approach in real-data based simulator which emulates an industrial production environment where several resource providers compete to perform different tasks. The results pointed that multi-dimensional fairness incentives agents to remain in the market whilst it improves the equity of the wealth distribution without compromising the quality of the allocation attributes. © 2014 Elsevier B.V.All rights reserved.


Pla A.,University of Girona | Lopez B.,University of Girona | Murillo J.,Newronia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Multi-attribute auctions allow agents to sell and purchase goods and services taking into account more attributes besides the price (e.g. service time, tolerances, qualities, etc.). The coexistence of different attributes in the auction mechanism increases the difficulty of determining the winner and its payment. multi-criteria functions can be used to deal with the problem of determining the auction winner. However, in order to make the payment possible, multi criteria functions must fulfill certain conditions. In this paper we discuss which properties must satisfy a multi-criteria function so it can be used to determine the winner of a multi-attribute auction and we experimentally show how the valuation function choice conditions the behavior of the auction mechanism. © 2012 Springer-Verlag.


Torrent F.,University of Girona | Munoz V.,Newronia | Lopez B.,University of Girona
Frontiers in Artificial Intelligence and Applications | Year: 2012

In this paper we introduce a new kind of immobile Location-Allocation problem that consists in determining the service each facility has to offer in order to maximize the covered demand given the positions of the customers and their service requirements and the positions of the immobile facilities. First, we provide a formalization of the problem and then we tackle the problem using two heuristic methods, genetic algorithms and simulated annealing, comparing the performance of both algorithms. © 2012 The authors and IOS Press. All rights reserved.


Newronia | Entity website

Last week, the European Electric Vehicle Congress (EEVC-2012) was held in Brussels, where issues such as EV manufacturing, components and platforms, among others, where discussed


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