149 research outputs found
RIGA: A Regret-Based Interactive Genetic Algorithm
In this paper, we propose an interactive genetic algorithm for solving
multi-objective combinatorial optimization problems under preference
imprecision. More precisely, we consider problems where the decision maker's
preferences over solutions can be represented by a parameterized aggregation
function (e.g., a weighted sum, an OWA operator, a Choquet integral), and we
assume that the parameters are initially not known by the recommendation
system. In order to quickly make a good recommendation, we combine elicitation
and search in the following way: 1) we use regret-based elicitation techniques
to reduce the parameter space in a efficient way, 2) genetic operators are
applied on parameter instances (instead of solutions) to better explore the
parameter space, and 3) we generate promising solutions (population) using
existing solving methods designed for the problem with known preferences. Our
algorithm, called RIGA, can be applied to any multi-objective combinatorial
optimization problem provided that the aggregation function is linear in its
parameters and that a (near-)optimal solution can be efficiently determined for
the problem with known preferences. We also study its theoretical performances:
RIGA can be implemented in such way that it runs in polynomial time while
asking no more than a polynomial number of queries. The method is tested on the
multi-objective knapsack and traveling salesman problems. For several
performance indicators (computation times, gap to optimality and number of
queries), RIGA obtains better results than state-of-the-art algorithms
Nonconvex optimization for pricing and hedging in imperfect markets.
The paper deals with imperfect financial markets and provides new methods to overcome many inefficiencies caused by frictions. Transaction costs are quite general and far from linear or convexo The concepts of pseudoarbitrage and efficiency are introduced and deeply analyzed by means of both scalar and vector optimization problems. Their optimality conditions and solutions yield strategies to invest and hedging portfolios, as well as bid-ask spread improvements. They also point out the role of coalitions when dealing with these markets. Several sensitivity results will permit us to show that a significant transaction costs reduction is very often feasible in practice, as well as to measure its effect on the general efficiency of the market. AII these findings may be especially important for many emerging and still illiquid spot or derivative markets (electricity markets, com odity markets, markets related to weather, infiation-linked or insurance-linked derivatives, etc.).Global optimization; Pseudoarbitrage; Spread reduction; Balance point;
A Tabu Search Based Metaheuristic for Dynamic Carpooling Optimization
International audienceThe carpooling problem consists in matching a set of riders' requests with a set of drivers' offers by synchronizing their origins, destinations and time windows. The paper presents the so-called Dynamic Carpooling Optimization System (DyCOS), a system which supports the automatic and optimal ridematching process between users on very short notice or even en-route. Nowadays, there are numerous research contributions that revolve around the carpooling problem, notably in the dynamic context. However, the problem's high complexity and the real time aspect are still challenges to overcome when addressing dynamic carpooling. To counter these issues, DyCOS takes decisions using a novel Tabu Search based metaheuristic. The proposed algorithm employs an explicit memory system and several original searching strategies developed to make optimal decisions automatically. To increase users' satisfaction, the proposed metaheuristic approach manages the transfer process and includes the possibility to drop off the passenger at a given walking distance from his destination or at a transfer node. In addition, the detour concept is used as an original aspiration process, to avoid the entrapment by local solutions and improve the generated solution. For a rigorous assessment of generated solutions , while considering the importance and interaction among the optimization criteria, the algorithm adopts the Choquet integral operator as an aggregation approach. To measure the effectiveness of the proposed method, we develop a simulation environment based on actual carpooling demand data from the metropolitan area of Lille in the north of France
Multi crteria decision making and its applications : a literature review
This paper presents current techniques used in Multi Criteria Decision Making (MCDM) and their applications. Two basic approaches for MCDM, namely Artificial Intelligence MCDM (AIMCDM) and Classical MCDM (CMCDM) are discussed and investigated. Recent articles from international journals related to MCDM are collected and analyzed to find which approach is more common than the other in MCDM. Also, which area these techniques are applied to. Those articles are appearing in journals for the year 2008 only. This paper provides evidence that currently, both AIMCDM and CMCDM are equally common in MCDM
Robust ordinal regression for value functions handling interacting criteria
International audienceWe present a new method called UTAGMSâINT for ranking a finite set of alternatives evaluated on multiple criteria. It belongs to the family of Robust Ordinal Regression (ROR) methods which build a set of preference models compatible with preference information elicited by the Decision Maker (DM). The preference model used by UTAGMSâINT is a general additive value function augmented by two types of components corresponding to ââbonusââ or ââpenaltyââ values for positively or negatively interacting pairs of criteria, respectively. When calculating value of a particular alternative, a bonus is added to the additive component of the value function if a given pair of criteria is in a positive synergy for performances of this alternative on the two criteria. Similarly, a penalty is subtracted from the additive component of the value function if a given pair of criteria is in a negative synergy for performances of the considered alternative on the two criteria. The preference information elicited by the DM is composed of pairwise comparisons of some reference alternatives, as well as of comparisons of some pairs of reference alternatives with respect to intensity of preference, either comprehensively or on a particular criterion. In UTAGMSâINT, ROR starts with identification of pairs of interacting criteria for given preference information by solving a mixed-integer linear program. Once the interacting pairs are validated by the DM, ROR continues calculations with the whole set of compatible value functions handling the interacting criteria, to get necessary and possible preference relations in the considered set of alternatives. A single representative value function can be calculated to attribute specific scores to alternatives. It also gives values to bonuses and penalties. UTAGMSâINT handles quite general interactions among criteria and provides an interesting alternative to the Choquet integral
Nonconvex optimization for pricing and hedging in imperfect markets
The paper deals with imperfect financial markets and provides new methods to overcome
many inefficiencies caused by frictions. Transaction costs are quite general and far from linear
or convexo The concepts of pseudoarbitrage and efficiency are introduced and deeply analyzed by
means of both scalar and vector optimization problems. Their optimality conditions and solutions
yield strategies to invest and hedging portfolios, as well as bid-ask spread improvements. They also
point out the role of coalitions when dealing with these markets. Several sensitivity results will permit
us to show that a significant transaction costs reduction is very often feasible in practice, as well as to
measure its effect on the general efficiency of the market. AII these findings may be especially important
for many emerging and still illiquid spot or derivative markets (electricity markets, com odity
markets, markets related to weather, infiation-linked or insurance-linked derivatives, etc.).Partially funded by "Comunidad AutĂłnoma de Madrid" and Spanish Ministry of Science and Education (ref:
BEC2003-09067 -C04-03).Publicad
A Fuzzy-based Framework to Support Multicriteria Design of Mechatronic Systems
Designing a mechatronic system is a complex task since it deals with a high
number of system components with multi-disciplinary nature in the presence of
interacting design objectives. Currently, the sequential design is widely used
by designers in industries that deal with different domains and their
corresponding design objectives separately leading to a functional but not
necessarily an optimal result. Consequently, the need for a systematic and
multi-objective design methodology arises. A new conceptual design approach
based on a multi-criteria profile for mechatronic systems has been previously
presented by the authors which uses a series of nonlinear fuzzy-based
aggregation functions to facilitate decision-making for design evaluation in
the presence of interacting criteria. Choquet fuzzy integrals are one of the
most expressive and reliable preference models used in decision theory for
multicriteria decision making. They perform a weighted aggregation by the means
of fuzzy measures assigning a weight to any coalition of criteria. This enables
the designers to model importance and also interactions among criteria thus
covering an important range of possible decision outcomes. However,
specification of the fuzzy measures involves many parameters and is very
difficult when only relying on the designer's intuition. In this paper, we
discuss three different methods of fuzzy measure identification tailored for a
mechatronic design process and exemplified by a case study of designing a
vision-guided quadrotor drone. The results obtained from each method are
discussed in the end
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