We study the global cardinality constraint (gcc) and propose an O(n1.5d) algorithm for domain consistency and an O(cn + dn) algorithm for range consistency where n is the number of variables, d the number of values in...
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作者:
Bistarelli, S.Gennari, R.Rossi, F.Università di Pisa
Dipartimento di Informatica Corso Italia 40 Pisa56125 Italy ILLC
Institute of Logic Language and Computation University of Amsterdam N. Doelenstraat 15 Amsterdam1012 CP Netherlands Università di Padova
Dipartimento di Matematica Pura ed Applicata Via Belzoni 7 Padova35131 Italy
Soft constraints based on semirings are a generalization of classical constraints, where tuples of variables’ values in each soft constraint are uniquely associated to elements from an algebraic structure called semi...
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Bound consistency can easily and efficiently be enforced on linear constraint. However, bound consistency techniques deal with every constraint separately. We show that in some cases much stronger bounds can be comput...
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constraint satisfaction problems (CSPs) sometimes contain both variable symmetries and value symmetries, causing adverse effects on CSP solvers based on tree search. As a remedy, symmetry breaking constraints are comm...
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constraint satisfaction problems (CSPs) sometimes contain both variable symmetries and value symmetries, causing adverse effects on CSP solvers based on tree search. As a remedy, symmetry breaking constraints are commonly used. While variable symmetry breaking constraints can be expressed easily and propagated efficiently using lexicographic ordering, value symmetry breaking constraints are often difficult to formulate. In this paper, we propose two methods of using symmetry breaking constraints to tackle value symmetries. First, we show theoretically when value symmetries in one CSP correspond to variable symmetries in another CSP of the same problem. We also show when variable symmetry breaking constraints in the two CSPs, combined using channeling constraints, are consistent. Such results allow us to tackle value symmetries efficiently using additional CSP variables and channeling constraints. Second, we introduce value precedence, a notion which can be used to break a common class of value symmetries, namely symmetries of indistinguishable values. While value precedence can be expressed using inefficient if-then constraints in existing CSP solvers, we propose efficient propagation algorithms for implementing global value precedence constraints. We also characterize several theoretical properties of the value precedence constraints. Extensive experiments are conducted to verify the feasibility and efficiency of the two proposals.
CGLIB is a high-level graphics library for B-Prolog, a constraint logic programming system. the library provides primitives for creating and manipulating graphical objects and a set of constraints including non-overla...
ISBN:
(纸本)3540232419
CGLIB is a high-level graphics library for B-Prolog, a constraint logic programming system. the library provides primitives for creating and manipulating graphical objects and a set of constraints including non-overlap, grid, table, and tree constraints that facilitates the specification of the layouts of objects. the library adopts a construct called action rules available in B-Prolog for creating agents and programming interactions among agents or between agents and the user. the library is a fully working system implemented in B-Prolog, Java and C. It can be used in many areas such as drawing editors, interactive user interfaces, document authoring, animation, information visualization, intelligent agents, and games. the high-level abstraction of the library and the use of constraints and action rules in the specification of layouts and behaviors can significantly enhance the productivity of the development of graphics. We demonstrate through several examples the effectiveness of the library as a tool for developing graphics-rich and interactive user interfaces. the system is available from *** and the details of the library can be found in [1].
We provide a reformulation of the constraint hierarchies (CHs) framework based on the notion of error indicators. Adapting the generalized view of local consistency in semiring-based constraint satisfaction problems (...
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Scheduling is one of the most successful application areas of constraintprogramming mainly thanks to special global constraints designed to model resource restrictions. Among these global constraints, edge-finding fi...
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this paper presents a model and implementation techniques for speeding up constraint propagation. Two fundamental approaches to improving constraint propagation are explored: keeping track of which propagators are at ...
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constraint programs containing a matrix of two (or more) dimensions of decision variables often have row and column symmetries: in any assignment to the variables the rows can be swapped and the columns can be swapped...
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In this paper, we address the task of finding the minimal network of a Temporal constraint Satisfaction Problem (TCSP).We report the integration of three approaches to improve the performance of the exponential-time b...
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