This paper presents a first approach to a constraint programming-based library for the modelling of general vehicle routing problems (VRP). In this work we present a set of constraints and cost functions written in EC...
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This paper presents a first approach to a constraint programming-based library for the modelling of general vehicle routing problems (VRP). In this work we present a set of constraints and cost functions written in ECLiPSe, a well known constraint programming (CP) language, which can be combined to build different VRP models without rewriting.
The paper introduces the concept of a crystalline-like model of a computer communication network (CCN) composed of routers forming a repeating or periodic arrangement. The considered homogenous network assumes the sam...
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The paper introduces the concept of a crystalline-like model of a computer communication network (CCN) composed of routers forming a repeating or periodic arrangement. The considered homogenous network assumes the same routers servicing the same number of transmissions form an array. In such a network several isomorphic sub-networks encompassing packet transmission processes serviced by each router, interact each other as to provide a variety of demand-responsive host-server transmission services. In that context, a crystalline-like layout of physically different, however functionally identical, routers provides a homogenous array supporting computer network flows. In turn, packet transmission flows are treated as multimodal processes encompassing arbitrarily given inter-computer communications. Assuming the packets passing their origin-destination routes are synchronized by the same mechanism of packet transmission the problem boils down to a communication processes scheduling. Since concurrent transmission flows are processed along the same presumed routes, hence the schedules sought are cyclic ones. In general case, cycles of multimodal processes depend on CNN's periodicity. That objective to develop conditions allowing one to calculate the cyclic schedule of whole CCN while taking into account only periodicity of its repeating isomorphic structure.
Model reduction is a central topic in systems biology and dynamical systems theory, for reducing the complexity of detailed models, finding important parameters, and developing multi-scale models for instance. While s...
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Model reduction is a central topic in systems biology and dynamical systems theory, for reducing the complexity of detailed models, finding important parameters, and developing multi-scale models for instance. While singular perturbation theory is a standard mathematical tool to analyze the different time scales of a dynamical system and decompose the system accordingly, tropical methods provide a simple algebraic framework to perform these analyses systematically in polynomial systems. The crux of these methods is in the computation of tropical equilibrations. In this paper we show that constraint-based methods, using reified constraints for expressing the equilibration conditions, make it possible to numerically solve non-linear tropical equilibration problems, out of reach of standard computation methods. We illustrate this approach first with the detailed reduction of a simple biochemical mechanism, the Michaelis-Menten enzymatic reaction model, and second, with large-scale performance figures obtained on the http://*** repository.
Picat is a new and interesting programming language,combing many different programming paradigms:logic programming,imperative programming,functional programming,constraint programming,and *** paper is a personal discu...
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Picat is a new and interesting programming language,combing many different programming paradigms:logic programming,imperative programming,functional programming,constraint programming,and *** paper is a personal discussion of some of Picat's features with several code examples.
This paper considers a parallel-machine scheduling problem with noncontinuous available machines in the horizon planning. The problem is converted from the housekeeper assignment in hotels while the information of arr...
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This paper considers a parallel-machine scheduling problem with noncontinuous available machines in the horizon planning. The problem is converted from the housekeeper assignment in hotels while the information of arrival and leaving times can be obtained from the reservation system in advance. The objective of the problem is to minimize total weighted tardiness which implies to minimize the waiting time for the customers entering into the rooms. For this problem we formulate a constraint programming model where if-then logics can be used in it and examine the model by some generated instances. Computational results show that the model is valid and can solve 30 rooms(jobs) with 6 housekeepers(machines) in a reasonable time. Based on this study,it is obvious that the proposed model could arrange the housekeeper resources efficiently in hotels.
In this work we exploit search process features to dynamically adapt a constraint programming solver in order to more efficiently solve constraint Satisfaction Problems. The main novelty of our approach is that we rec...
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ISBN:
(纸本)9783901509704
In this work we exploit search process features to dynamically adapt a constraint programming solver in order to more efficiently solve constraint Satisfaction Problems. The main novelty of our approach is that we reconfigure the search based solely on performance data gathered while solving the current problem. We report encouraging results where our combination of strategies outperforms the use of individual strategies.
When the steady states are largely predominant with respect to transitional phases, steady-state simulation seems sufficient to predict the behavior of a complex system. Over the past 20 years, different modeling lang...
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When the steady states are largely predominant with respect to transitional phases, steady-state simulation seems sufficient to predict the behavior of a complex system. Over the past 20 years, different modeling languages and dedicated tools have been developed to improve steady state simulation. In this paper, focus is made on steady-state simulation for system control and design. A model combining an emission sub-model with a ship propulsion sub-model was implemented in a constraint programming (CP) approach. It will help to determine the efficiency (i.e. the ability to model and solve the problem) and complexity of implementation (i.e. difficulties encountered during the implementation) of this approach. First, requirements for the steady-state simulation of complex systems are defined. Then, CP approach is shown to be able to answer these issues through experiments. This approach is then compared to one of the main simulation languages: Modelica. Although the two approaches (i.e Modelica and CP) are able to reverse models, the study shows that the use of Modelica principles for steady-state simulation involves some crippling limitations, such as the nonmanagement of under/over-constrained systems, or inequalities. This study also shows that the constraint programming approach permits to meet some needs for steady-state simulation not yet covered by current approaches. (C) 2012 Elsevier Ltd. All rights reserved.
For the enterprises organised in several distributed production sites, usually, production scheduling models presume either an instantaneous delivery of products or an unlimited number of available vehicles for transp...
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For the enterprises organised in several distributed production sites, usually, production scheduling models presume either an instantaneous delivery of products or an unlimited number of available vehicles for transporting products. However, the transportation of the intermediate products to the sites is an important activity within the whole process of manufacturing, and the efficient coordination of production and transportation becomes a challenging problem in the actual higher collaborative and competitive environments. This work focuses on the integrated production and transportation scheduling properly managing the resources capacity, material flows and temporal interdependencies between sites. A case-study is reported and the industrial problem under consideration is modelled as a constraint satisfaction problem (CSP). Besides scheduling under resource constraints, the model presented in this paper expands the packing problem to the area of transportation operations scheduling. It is implemented under the constraint programming language CHIP V5. The provided solutions determine values for the various variables associated to the production and transportation operations realised on the whole multi-site, as well as the curves with the profile of the total consumption of resources in time.
Many real-life problems are over-constrained, so that no solution satisfying all their constraints exists. Soft constraints, with costs denoting how much the constraints are violated, are used to solve these problems....
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Many real-life problems are over-constrained, so that no solution satisfying all their constraints exists. Soft constraints, with costs denoting how much the constraints are violated, are used to solve these problems. We use the edit-distance based SoftRegular constraint as an example to show that a propagation algorithm that sometimes underestimates the cost may guide the search to incorrect (non-optimal) solutions to an over-constrained problem. To compute correctly the cost for the edit-distance based SoftRegular constraint, we present a quadratic-time propagation algorithm based on dynamic programming and a proof of its correctness. We also give an improved propagation algorithm using an idea of computing the edit distance between two strings, which may also be applied to other constraints with propagators based on dynamic programming. The asymptotic time complexity of our improved propagator is always at least as good as the one of our quadratic-time propagator, but significantly better when the edit distance is small. Our propagators achieve domain consistency on the problem variables and bounds consistency on the cost variable. Our method can also be adapted for the violation measure of the edit-distance based Regular constraint for constraint-based local search.
We consider the problem of determining whether a given set of rectangular items can be cut from a larger rectangle using so-called guillotine cuts only. We introduce a new class of arc-colored directed graphs called g...
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We consider the problem of determining whether a given set of rectangular items can be cut from a larger rectangle using so-called guillotine cuts only. We introduce a new class of arc-colored directed graphs called guillotine graphs and show that each guillotine graph can be associated with a specific class of pattern solutions that we call a guillotine-cutting class. The properties of guillotine graphs are examined, and some effective algorithms for dealing with guillotine graphs are proposed. As an application, we then describe a constraint programming method based on guillotine graphs, and we propose effective filtering techniques that use the graph model properties in order to reduce the search space efficiently. Computational experiments are reported on benchmarks from the literature: our algorithm outperforms previous methods when solving the most difficult instances exactly.
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