CLPGUI is a generic graphical user interface for visualizing and controlling the execution of constraint logic programs. CLPGUI has been designed to be used in different contexts: initially for teaching purposes, then...
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CLPGUI is a generic graphical user interface for visualizing and controlling the execution of constraint logic programs. CLPGUI has been designed to be used in different contexts: initially for teaching purposes, then for debugging complex programs of real-world scale, and recently for developing end-user interfaces. The challenge of developing a tool which is generic w.r.t. both the constraint logic programming system and the visualizers, is addressed by a client-server architecture for connecting a CLP process to a Java-based GUI process, and by a non-intrusive tracing and control method based on annotations in the CLP program. Arbitrary constraints and goals can be posted incrementally from the GUI in an interactive manner, and arbitrary states can be recomputed. We describe several generic 2D and 3D viewers of the variables and of the search tree, and argue that the 3D representation is best-suited to apprehend the shape of large search trees. We also illustrate the use of CLPGUI for developing application-oriented end-user interfaces on two placement problems, one in virtual reality.
Optimality-based reduction attempts to take advantage of the known bounds of the objective function to reduce the domain of the variables, and thus to speed up the search of a global optimum. However, the basic algori...
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ISBN:
(纸本)9781595934802
Optimality-based reduction attempts to take advantage of the known bounds of the objective function to reduce the domain of the variables, and thus to speed up the search of a global optimum. However, the basic algorithm is unsafe, and thus, the overall process may no longer be complete and may not reach the actual global optimum. Recently, Kear-fott has proposed a safe implementation of optimality-based reduction. Unfortunately, his method suffers from some limitations and is rather slow. In this paper, we show how constraint programming filtering techniques can be used to implement optimality-based reduction in a safe and efficient way.
Many knowledge-based applications require knowledge maintenance to keep the application functional throughout its lifecycle. In this paper we present iCAM, a constraint-based knowledge maintenance system that operates...
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ISBN:
(纸本)9781595936431
Many knowledge-based applications require knowledge maintenance to keep the application functional throughout its lifecycle. In this paper we present iCAM, a constraint-based knowledge maintenance system that operates in a hospital's material management domain. iCAM uses consistency algorithms to assist users in placing orders and making order corrections, and to ensure that maintenance activities are consistent with the department's ordering environment. This approach allows iCAM to interact with the user to revise orders and/or to update the knowledge base. For the user, there is not much distinction between these two tasks. This is one of iCAM's greatest strengths;order corrections and knowledge maintenance are carried out in a similar manner, since both are based on inconsistencies with respect to the existing knowledge base. iCAM has various constraint types that support physical and policy restrictions. It also allows maintenance to be done by a number of users while maintaining the integrity of the knowledge base by a system of role restrictions.
Action description languages, such as A and B [6], are expressive instruments introduced for formalizing planning domains and problems. The paper starts by proposing a methodology to encode an action language (with co...
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ISBN:
(纸本)9783540746089
Action description languages, such as A and B [6], are expressive instruments introduced for formalizing planning domains and problems. The paper starts by proposing a methodology to encode an action language (with conditional effects and static causal laws), a slight variation of B, using constraint Logic programming over Finite Domains. The approach is then generalized to lift the use of constraints to the level of the action language itself. A prototype implementation has been developed, and the preliminary results are presented and discussed.
LODE is a logic-based web tool for Italian deaf children. It aims at stimulating global reasoning on e-stories written in a verbal language. Presently, we are focusing on temporal reasoning, that is, LODE stimulates c...
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ISBN:
(纸本)9783540749691
LODE is a logic-based web tool for Italian deaf children. It aims at stimulating global reasoning on e-stories written in a verbal language. Presently, we are focusing on temporal reasoning, that is, LODE stimulates children to reason with global temporal relations between events possibly distant in a story. This is done through apt exercises and with the support of a constraint programming system. Children can also reinvent the e-story by rearranging its events along a new temporal order;it is the task of the constraint system to determine the consistency of the temporally reorganised story and provide children with feedback. To the best of our knowledge, LODE is the first e-learning tool for Italian deaf children that aims at stimulating global reasoning on whole e-stories.
In this paper, we propose a new language, called AR (Action Rules), and describe how various propagators for finite-domain constraints can be implemented in it. An action rule specifies a pattern for agents, an action...
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In this paper, we propose a new language, called AR (Action Rules), and describe how various propagators for finite-domain constraints can be implemented in it. An action rule specifies a pattern for agents, an action that the agents can carry out, and an event pattern for events that can activate the agents. AR combines the goal-oriented execution model of logic programming with the event-driven execution model. This hybrid execution model facilitates programmingconstraint propagators. A propagator for a constraint is an agent that maintains the consistency of the constraint and is activated by the updates of the domain variables in the constraint. AR has a much stronger descriptive power than indexicals, the language widely used in the current finite-domain constraint systems, and is flexible for implementing not only interval-consistency but also arc-consistency algorithms. As examples, we present a weak arc-consistency propagator for the all-distinct constraint and a hybrid algorithm for n-ary linear equality constraints. B-Prolog has been extended to accommodate action rules. Benchmarking shows that B-Prolog as a CLP(FD) system significantly outperforms other CLP(FD) systems.
Partially Defined constraints can be used to model the incomplete knowledge of a concept or a relation. Instead of only computing with the known part of the constraint, we propose to complete its definition by using M...
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Partially Defined constraints can be used to model the incomplete knowledge of a concept or a relation. Instead of only computing with the known part of the constraint, we propose to complete its definition by using Machine Learning techniques. Since constraints are actively used during solving for pruning domains, building a classifier for instances is not enough: we need a solver able to reduce variable domains. Our technique is composed of two steps: first we learn a classifier for each constraint projections and then we transform the classifiers into a propagator. The first contribution is a generic meta-technique for classifier improvement showing performances comparable to boosting. The second lies in the ability of using the learned concept in constraint-based decision or optimization problems. We presents results using Decision Trees and Artificial Neural Networks for constraint learning and propagation. It opens a new way of integrating Machine Learning in Decision Support Systems.
In this paper we present GRASPER, a graph constraint solver, based on set constraints, that shows promising results when compared to an existing similar solver at this early stage of development.
ISBN:
(纸本)9783540770008
In this paper we present GRASPER, a graph constraint solver, based on set constraints, that shows promising results when compared to an existing similar solver at this early stage of development.
In interval propagation approaches to solving non-linear constraints over reals it is common to build stronger propagators from systems of linear equations. This, as far as we axe aware, is not pursued for integer fin...
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ISBN:
(纸本)9781595934802
In interval propagation approaches to solving non-linear constraints over reals it is common to build stronger propagators from systems of linear equations. This, as far as we axe aware, is not pursued for integer finite domain propagation. In this paper we show how we can add preconditioning Gauss-Seidel based propagators to an integer propagation solver. The Gauss-Seidel based propagators make use of interval arithmetic which is substantially slower than integer arithmetic. We show how we can build new integer propagators from the result of preconditioning that no longer require interval arithmetic to be performed. Although the resulting propagators may be slightly weaker than the original Gauss-Seidel propagation, they are substantially faster. We show on standard integer benchmarks how these new propagators can substantially improve propagation performance, in terms of strength of propagation and speed.
This paper considers the problem of minimizing the traffic complexities in an airspace of adjacent sectors. The traffic complexity of a sector is determined by the numbers of flights within it, near its border, and on...
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This paper considers the problem of minimizing the traffic complexities in an airspace of adjacent sectors. The traffic complexity of a sector is determined by the numbers of flights within it, near its border, and on non-level segments within it. The dimensions of complexity resolution involve changing the take-off times of non-airborne flights, changing the approach times into the chosen airspace of airborne flights by slowing and accelerating within the two layers of feeder sectors around that airspace, as well as changing the attitude at way-points in that airspace. Experiments with European flight profiles from the Central Flow Management Unit show that these forms of resolution can lead to significant complexity reductions and rebalancing. (C) 2007 Elsevier Ltd. All rights reserved.
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