This paper investigates the use of abstract domains from Abstract Interpretation (AI) in the field of constraint programming (CP). CP solvers are generally very efficient on a specific constraint language, but can har...
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ISBN:
(纸本)9783030549961;9783030549978
This paper investigates the use of abstract domains from Abstract Interpretation (AI) in the field of constraint programming (CP). CP solvers are generally very efficient on a specific constraint language, but can hardly be extended to tackle more general languages, both in terms of variable representation (discrete or continuous) and constraint type (global, arithmetic, etc.). For instance, linear constraints are usually solved with linear programming techniques, but non-linear ones have to be either linearized, reformulated or sent to an external solver. We approach this problem by adapting to CP a popular domain construction used to combine the power of several analyses in AI: the reduced product. We apply this product on two well-known abstract domains, Boxes and Polyhedra, that we lift to constraint solving. Finally we define general metrics for the quality of the solver results, and present a benchmark accordingly. Experiments show promising results and good performances.
This paper describes a new approach to develop a real-world automated scheduler applicable for Australian sugarcane industry. In Australia, the transport sector plays a critical role in raw sugarcane harvest and accou...
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ISBN:
(纸本)9781728141497
This paper describes a new approach to develop a real-world automated scheduler applicable for Australian sugarcane industry. In Australia, the transport sector plays a critical role in raw sugarcane harvest and accounts for over 35% of the total cost of raw sugar production. The generation of an optimised schedule can bring the following practical benefits: eliminate bin supply delays to harvesters, minimise the number of locomotives/bins, reduce the locomotive shifts, control the sugarcane age/quality, etc. To generate such a scheduler, a new optimisation approach is developed based on job shop scheduling techniques using constraint programming and mixed integer programming. The proposed approach can produce solutions for small-scale and large-scale cases in agriculture/crops transport systems in a reasonable time. Mixed integer programming focuses on objective function using linear relaxation to prune suboptimal solutions, while constraint programming focuses on the model using filtering algorithms to eliminate infeasible candidate solutions. The applicability of the developed scheduler has been validated by a real-world case study for Kalamia Mill in Queensland, Australia. Following from the validation and discussion, it is concluded that the automated scheduler would be a valuable optimisation tool for transport modellers in Australian sugarcane industry.
constraint programming (CP) and answer set programming (ASP) are two declarative paradigms used to solve combinatorial problems. Many modern solvers for both these paradigms rely on partial or complete Boolean represe...
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ISBN:
(纸本)9781921770203
constraint programming (CP) and answer set programming (ASP) are two declarative paradigms used to solve combinatorial problems. Many modern solvers for both these paradigms rely on partial or complete Boolean representations of the problem to exploit the extremely efficient techniques that have been developed for solving propositional satisfiability problems. This convergence on a common representation makes it possible to incorporate useful features of CP into ASP and vice versa. There has been significant effort in recent years to integrate CP into ASP, primarily to overcome the grounding bottleneck in traditional ASP solvers that exists due to their inability to handle integer variables efficiently. On the other hand, ASP solvers are more efficient than CP systems on problems that involve inductive definitions, such as reachability in a graph. Besides efficiency, ASP syntax is more natural and closer to the mathematical definitions of such concepts. In this paper, we describe an approach that adds support for answer set rules to a CP system, namely the lazy clause generation solver chuffed. This integration also naturally avoids the grounding bottleneck of ASP since constraint solvers natively support finite domain variables. We demonstrate the usefulness of our approach by comparing our new system against two competitors: the state-of-the-art ASP solver clasp, and clingcon, a system that extends clasp with CP capabilities.
Many organizations have adapted flexible working arrangements during COVID19 pandemic because of restrictions on the number of employees required on site at any time. Unfortunately, current employee scheduling methods...
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Many organizations have adapted flexible working arrangements during COVID19 pandemic because of restrictions on the number of employees required on site at any time. Unfortunately, current employee scheduling methods are more suited for compressed working arrangements. The problem of automating compressed employee scheduling has been studied by many researchers and is widely adopted by many organizations in an attempt to achieve high quality scheduling. During process of employee scheduling many constraints may have to be considered and may require negotiating a large dimension of constraints like in flexible working. These constraints make scheduling a challenging task in these working arrangements. Most scheduling algorithms are modeled as constraint optimization problems and suited for compressed work but for flexible working with large constraint dimensions, achieving accurate scheduling is even more challenging. In this research, we propose a machine learning approach that takes advantage of mining user-defined constraints or soft constraints and transform employee scheduling into a classification problem. We propose automatically extracting employee personal schedules like calendars in order to extract their availability. We then show how to use the extracted knowledge in a multi-label classification approach in order to generate a schedule for faculty staff in a University that supports flexible working. We show that the results of this approach are comparable to that of a constraint satisfaction and optimization method that is commonly used in literature. Results show that our approach achieved accuracy of 93.1% of satisfying constraints as compared to 92.7% of a common constraint programming approach.
The performance of a constraint problem can often be improved by converting a subproblem into a single regular constraint. We describe a new approach to optimize constraint satisfaction (optimization) problems using c...
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ISBN:
(纸本)9783030582845;9783030582852
The performance of a constraint problem can often be improved by converting a subproblem into a single regular constraint. We describe a new approach to optimize constraint satisfaction (optimization) problems using constraint transformations from different kinds of global constraints to regular constraints, and their combination. Our transformation approach has two aims: 1. to remove redundancy originating from semantically overlapping constraints over shared variables and 2. to remove origins of backtracks in the search during the solution process. Based on the case study of the Warehouse Location Problem we show that our new approach yields a significant speed-up.
Pour répondre aux objectifs de consommation des flottes de véhicules, au normes d’émissions de polluants et aux nouvelles demandes de l’usager, les constructeurs automobiles doivent développer de...
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Pour répondre aux objectifs de consommation des flottes de véhicules, au normes d’émissions de polluants et aux nouvelles demandes de l’usager, les constructeurs automobiles doivent développer des motorisations hybrides et électriques. Réaliser une chaine de traction hybride reste cependant une tâche difficile. Ces systèmes sont complexes et possèdent de nombreuses variables réparties sur différents niveaux : architecture, technologie des composants, dimensionnement et contrôle/commande. L’industrie manque encore d’environnements et d’outils pouvant aider à l’exploration de l’ensemble de l’espace de dimensionnement et à trouver la meilleure solution parmi tous ces niveaux. Cette thèse propose une méthodologie systématique pour répondre au moins partiellement à ce besoin. Partant d’un ensemble de composants, cette méthodologie permet de générer automatiquement tous les graphes d’architectures possibles en utilisant la technique de programmation par contraintes. Une représentation dédiée est développée pour visualiser ces graphes. Les éléments de boites de vitesse (embrayages, synchroniseurs) sont représentés avec un niveau de détails approprié pour générer de nouvelles transmission mécaniques sans trop complexifier le problème. Les graphes obtenus sont ensuite transformés en d’autres types de représentation : 0ABC Table (décrivant les connections mécaniques entre les composants), Modes Table (décrivant les modes de fonctionnement disponibles dans les architectures) et Modes Table + (décrivant pour chaque mode le rendement et le rapport de réduction global des chemins de transfert de l’énergie entre tous les composants). Sur la base de cette représentation, les nombreuses architectures générées sont filtrées et seules les plus prometteuses sont sélectionnées. Elles sont ensuite automatiquement évaluées et optimisées avec un modèle général spécifiquement développé pour calculer les performances et la consommation de toute les architectures générées. Ce modèle est insér
Most existing researches on cloud workflow systems have focused on resource scheduling with the aims to minimize system delay under budget constraints or optimize system cost under deadline constraints. However, cloud...
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ISBN:
(纸本)9781728187808
Most existing researches on cloud workflow systems have focused on resource scheduling with the aims to minimize system delay under budget constraints or optimize system cost under deadline constraints. However, cloud providers cannot guarantee a failure-free cloud environment, a compact scheduling plan is prone to failure, thus, workflow system reliability has been identified as a critical and challenging issue in the volatile cloud environment. With the ability of cloud, it is easy for users to implement the active fault tolerance schemes, e.g., Scale-Out. However, it will lead to issues like security problem and extra management cost. In this paper, we first investigate Scale-Up and Scale-Hybrid schemes to fully explore the possibilities offered by the ability of cloud. We formally model the problem of optimizing the reliability of a cloud workflow system under budget constraints with these three fault-tolerance schemes. These optimization problems are discrete and non-convex. Thus, we propose a genetic algorithm based method for workflow fault tolerance (GA4WFT). Finally, we evaluate the effectiveness and efficiency of proposed GA4WFT with three different fault-tolerance schemes through experiments conducted on Amazon EC2 data.
In today’s rapid production scenario, scheduling plays a dynamic role in planning. In this work, open shop scheduling problem related to a copper flexible braids manufacturing company is considered. In a scheduling p...
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Defeasible reasoning, critical for commonsense reasoning and uncertainty handling, has garnered significant attention in AI community. This interest is particularly pronounced in the development and evaluation of Larg...
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The Job-Shop Scheduling Problem (JSSP) is a well-known optimization problem with plenty of existing solutions. Although remarkable progress has been made in addressing the problem, most of the solutions require input ...
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