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51
Partial Constraint Satisfaction
, 1992
"... . A constraint satisfaction problem involves finding values for variables subject to constraints on which combinations of values are allowed. In some cases it may be impossible or impractical to solve these problems completely. We may seek to partially solve the problem, in particular by satisfying ..."
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Cited by 453 (21 self)
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. A constraint satisfaction problem involves finding values for variables subject to constraints on which combinations of values are allowed. In some cases it may be impossible or impractical to solve these problems completely. We may seek to partially solve the problem, in particular by satisfying a maximal number of constraints. Standard backtracking and local consistency techniques for solving constraint satisfaction problems can be adapted to cope with, and take advantage of, the differences between partial and complete constraint satisfaction. Extensive experimentation on maximal satisfaction problems illuminates the relative and absolute effectiveness of these methods. A general model of partial constraint satisfaction is proposed. 1 Introduction Constraint satisfaction involves finding values for problem variables subject to constraints on acceptable combinations of values. Constraint satisfaction has wide application in artificial intelligence, in areas ranging from temporal r...
Hybrid Algorithms for the Constraint Satisfaction Problem
 Computational Intelligence
, 1993
"... problem (csp), namely, naive backtracking (BT), backjumping (BJ), conflictdirected backjumping ..."
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Cited by 375 (8 self)
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problem (csp), namely, naive backtracking (BT), backjumping (BJ), conflictdirected backjumping
ConjunctiveQuery Containment and Constraint Satisfaction
 Journal of Computer and System Sciences
, 1998
"... Conjunctivequery containment is recognized as a fundamental problem in database query evaluation and optimization. At the same time, constraint satisfaction is recognized as a fundamental problem in artificial intelligence. What do conjunctivequery containment and constraint satisfaction have in c ..."
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Cited by 157 (15 self)
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Conjunctivequery containment is recognized as a fundamental problem in database query evaluation and optimization. At the same time, constraint satisfaction is recognized as a fundamental problem in artificial intelligence. What do conjunctivequery containment and constraint satisfaction have in common? Our main conceptual contribution in this paper is to point out that, despite their very different formulation, conjunctivequery containment and constraint satisfaction are essentially the same problem. The reason is that they can be recast as the following fundamental algebraic problem: given two finite relational structures A and B, is there a homomorphism h : A ! B? As formulated above, the homomorphism problem is uniform in the sense that both relational structures A and B are part of the input. By fixing the structure B, one obtains the following nonuniform problem: given a finite relational structure A, is there a homomorphism h : A ! B? In general, nonuniform tractability results do not uniformize. Thus, it is natural to ask: which tractable cases of nonuniform tractability results for constraint satisfaction and conjunctivequery containment do uniformize? Our main technical contribution in this paper is to show that several cases of tractable nonuniform constraint satisfaction problems do indeed uniformize. We exhibit three nonuniform tractability results that uniformize and, thus, give rise to polynomialtime solvable cases of constraint satisfaction and conjunctivequery containment.
Fuzzy Constraint Satisfaction
 In Proc. 3rd IEEE International Conference on Fuzzy Systems
, 1994
"... In this paper the issue of soft constraint satisfaction is discussed from a fuzzy set theoretical point of view. A fuzzy constraint is considered as a fuzzy relation. Different possible definitions for the degree of joint satisfaction of a set of fuzzy constraints are given, covering specific other ..."
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Cited by 102 (0 self)
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In this paper the issue of soft constraint satisfaction is discussed from a fuzzy set theoretical point of view. A fuzzy constraint is considered as a fuzzy relation. Different possible definitions for the degree of joint satisfaction of a set of fuzzy constraints are given, covering specific other soft constraint satisfaction problem (CSP) types such a partial and hierarchical CSP. It is shown that the classical CSP solving heuristics based on variable and value evaluations can be generalised and used to guide the solution construction process for solving fuzzy CSPs, and that the heuristic search can be replaced by branchandbound search. The solution process is illustrated with an example from the CSP literature. Finally, research issues are discussed. 1. Introduction In the recent years there has been a growing interest in soft constraint satisfaction. In general, in a soft CSP not all the given constraints need to be satisfied  either because all of them cannot be met, theoret...
Extracting Buildings from Aerial Images using Hierarchical Aggregation in 2D and 3D
, 1998
"... We propose a modelbased approach to automated 3D extraction of buildings from aerial images. We focus on a reconstruction strategy that is not restricted to a small class of buildings. Therefore, we employ a generic modeling approach which relies on the well dened combination of building part mo ..."
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Cited by 73 (4 self)
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We propose a modelbased approach to automated 3D extraction of buildings from aerial images. We focus on a reconstruction strategy that is not restricted to a small class of buildings. Therefore, we employ a generic modeling approach which relies on the well dened combination of building part models. Building parts are classied by their roof type.
Domain Filtering Consistencies
 Journal of Artificial Intelligence Research (JAIR)
, 2001
"... Enforcing local consistencies is one of the main features of constraint reasoning. Which level of local consistency should be used when searching for solutions in a constraint network is a basic question. Arc consistency and partial forms of arc consistency have been widely studied, and have been kn ..."
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Cited by 72 (8 self)
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Enforcing local consistencies is one of the main features of constraint reasoning. Which level of local consistency should be used when searching for solutions in a constraint network is a basic question. Arc consistency and partial forms of arc consistency have been widely studied, and have been known for sometime through the forward checking or the MAC search algorithms. Until recently, stronger forms of local consistency remained limited to those that change the structure of the constraint graph, and thus, could not be used in practice, especially on large networks. This paper focuses on the local consistencies that are stronger than arc consistency, without changing the structure of the network, i.e., only removing inconsistent values from the domains. In the last five years, several such local consistencies have been proposed by us or by others. We make an overview of all of them, and highlight some relations between them. We compare them both theoretically and experimentally, considering their pruning efficiency and the time required to enforce them.
Relative Representation of Spatial Knowledge: The 2D Case
, 1991
"... There have been some straightforward efforts to extend Allen's intervalbased temporal logic to spatial dimensions by using Cartesian tuples of relations [6]. We take a different approach based on a study of the kind of information that best relates two entities in 2dimensional space qualitati ..."
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Cited by 26 (5 self)
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There have been some straightforward efforts to extend Allen's intervalbased temporal logic to spatial dimensions by using Cartesian tuples of relations [6]. We take a different approach based on a study of the kind of information that best relates two entities in 2dimensional space qualitatively. The relevant spatial categories turn out to be "projection" and "orientation". We define a small set of spatial relations and stress the importance of making their reference frames explicit. Furthermore, we introduce "abstract maps", an analogical representation that inherently reflects the structure of the represented domain, and demonstrate their use in spatial reasoning. This scheme also facilitates "coarse" reasoning and the hierarchical organization of knowledge. These representational issues form the basis for an experimental system to develop "cognitive maps" from 2D scanned layout plans of buildings. 1 Introduction Cognitive spatial concepts are qualitative in nature. Despite the ...
Decision Procedures for Dependency Parsing Using Graded Constraints
 in proceedings of ACL'90
, 1998
"... We present an approach to the parsing of dependency structures which. brings together the notion of parsing as candidate elimination, the use of graded constraints, and the parallel disambiguation of related structural representations. The approach aims at an increased level of robustness by accepti ..."
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Cited by 24 (7 self)
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We present an approach to the parsing of dependency structures which. brings together the notion of parsing as candidate elimination, the use of graded constraints, and the parallel disambiguation of related structural representations. The approach aims at an increased level of robustness by accepting constraint violations in a controlled way, combining redundant and possibly conflicting information on different represenrational levels, and facilitating partial parsing as a natural mode of behavior.
Processing Fuzzy Spatial Queries: A Configuration Similarity Approach
 International Journal of Geographic Information Science
, 1998
"... . Increasing interest for configuration similarity is currently developing in the context of Digital Libraries, Spatial Databases and Geographical Information Systems. The corresponding queries retrieve all database configurations that match an input description (e.g., "find all configurations ..."
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Cited by 21 (1 self)
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. Increasing interest for configuration similarity is currently developing in the context of Digital Libraries, Spatial Databases and Geographical Information Systems. The corresponding queries retrieve all database configurations that match an input description (e.g., "find all configurations where an object x 0 is about 5km northeast of another x 1 , which, in turn, is inside object x 2 "). This paper introduces a framework for configuration similarity that takes into account all major types of spatial constraints (topological, direction, distance). We define appropriate fuzzy similarity measures for each type of constraint to provide flexibility and allow the system to capture reallife needs. Then we apply preprocessing techniques to explicate constraints in the query, and present algorithms that effectively solve the problem. Extensive experimental results demonstrate the applicability of our approach to images and queries of considerable size. 1. INTRODUCTION As opposed to visu...
Constraint Satisfaction and Database Theory: a Tutorial
 19th ACM Symposium on Principles of Database Systems
, 2000
"... A large class of problems in AI and other areas of computer science can be viewed as constraintsatisfaction problems. This includes problems in machine vision, belief maintenance, scheduling, temporal reasoning, type reconstruction, graph theory, and satisability. In general, the constraint satisfa ..."
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Cited by 21 (0 self)
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A large class of problems in AI and other areas of computer science can be viewed as constraintsatisfaction problems. This includes problems in machine vision, belief maintenance, scheduling, temporal reasoning, type reconstruction, graph theory, and satisability. In general, the constraint satisfactionproblem is NPcomplete, so searching for tractable cases is an active research area. It turns out that constraint satisfaction has an intimate connection with database theory: constraintsatisfaction problems can be recast as database problems and database problems can be recast as constraintsatisfaction problems. In this tutorial, I will cover the fundamentals of constraints saisfaction and describe its intimate relationship with database theory from various perspectives. 1 Introduction Since the early 1970s, researchers in articial intelligence have investigated a class of combinatorial problems that became known as constraintsatisfaction problems (CSP). The input to such a pro...