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Efficient solving of quantified inequality constraints over the real numbers
 ACM Transactions on Computational Logic
"... Let a quantified inequality constraint over the reals be a formula in the firstorder predicate language over the structure of the real numbers, where the allowed predicate symbols are ≤ and <. Solving such constraints is an undecidable problem when allowing function symbols such sin or cos. In t ..."
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Cited by 34 (9 self)
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Let a quantified inequality constraint over the reals be a formula in the firstorder predicate language over the structure of the real numbers, where the allowed predicate symbols are ≤ and <. Solving such constraints is an undecidable problem when allowing function symbols such sin or cos. In the paper we give an algorithm that terminates with a solution for all, except for very special, pathological inputs. We ensure the practical efficiency of this algorithm by employing constraint programming techniques. 1
Continuous FirstOrder Constraint Satisfaction
 ARTIFICIAL INTELLIGENCE, AUTOMATED REASONING, AND SYMBOLIC COMPUTATION, NUMBER 2385 IN LNCS
, 2002
"... This paper shows how to use constraint programming techniques for solving firstorder constraints over the reals (i.e., formulas in the firstorder predicate language over the structure of the real numbers). More specifically, based on a narrowing operator that implements an arbitrary notion of con ..."
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Cited by 27 (12 self)
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This paper shows how to use constraint programming techniques for solving firstorder constraints over the reals (i.e., formulas in the firstorder predicate language over the structure of the real numbers). More specifically, based on a narrowing operator that implements an arbitrary notion of consistency for atomic constraints over the reals (e.g., boxconsistency), the paper provides a narrowing operator for firstorder constraints that implements a corresponding notion of firstorder consistency, and a solver based on such a narrowing operator. As a consequence, this solver can take over various favorable properties from the field of constraint programming.
Qualitative Decision Making in Adaptive Presentation of Structured Information
 ACM TOIS
, 2003
"... We present a new approach for adaptive presentation of structured information, based on preferencebased constrained optimization techniques rooted in qualitative decisiontheory. ..."
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Cited by 10 (5 self)
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We present a new approach for adaptive presentation of structured information, based on preferencebased constrained optimization techniques rooted in qualitative decisiontheory.
Dynamic approximation of complex graphical constraints by linear constraints
 In Proceedings of the Fifteenth ACM Symposium on User Interface Software and Technology
, 2002
"... Current constraint solving techniques for interactive graphical applications cannot satisfactorily handle constraints such as nonoverlap, or containment within nonconvex shapes or shapes with smooth edges. We present a generic new technique for efficiently handling such kinds of constraints based ..."
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Cited by 8 (4 self)
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Current constraint solving techniques for interactive graphical applications cannot satisfactorily handle constraints such as nonoverlap, or containment within nonconvex shapes or shapes with smooth edges. We present a generic new technique for efficiently handling such kinds of constraints based on trust regions and linear arithmetic constraint solving. Our approach is to model these more complex constraints by a dynamically changing conjunction of linear constraints. At each stage, these give a local approximation to the complex constraints. During direct manipulation, linear constraints in the current local approximation can become active indicating that the current solution is on the boundary of the trust region for the approximation. The associated complex constraint is notified and it may choose to modify the current linear approximation. Empirical evaluation demonstrates that it is possible to (re)solve systems of linear constraints that are dynamically approximating complex constraints such as nonoverlap sufficiently quickly to support direct manipulation in interactive graphical applications. KEYWORDS: Constraintsolving, direct manipulation, trust regions, linearization of constraints, nonoverlap, containment.
A Presentation Language for Controlling the Formatting Process in Multimedia Presentations
 DOCENG'02
, 2002
"... Multimedia information encapsulated inside documents is more and more specific because its content is specified using domain vocabularies. Their integration in space and time to form a document implies transformation steps to produce "presentation structures". In this context presentation ..."
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Cited by 4 (0 self)
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Multimedia information encapsulated inside documents is more and more specific because its content is specified using domain vocabularies. Their integration in space and time to form a document implies transformation steps to produce "presentation structures". In this context presentation languages and formatters must be enhanced to cover new needs of rendering such as: multiple output of the same information or dynamic changing of the reader context. These new document models and processing architectures induce new editing and formatting services to be proposed to the author. This paper describes new presentation properties that can be added to existing presentation languages and that allow the author to express: priorities, more abstract properties and fallback positions. These properties are used by our formatter in order to provide more adaptive renderings. The architecture of this formatting service is open in order to be used for different presentation systems with different presentation languages. In this paper, we describe our experiment using priorities and optimization requests for temporal formatting.
Smooth Linear Approximation of Nonoverlap Constraints
"... Abstract. Constraintbased placement tools and their use in diagramming tools has been investigated for decades. One of the most important and natural placement constraints in diagrams is that their graphic elements do not overlap. However, nonoverlap of objects, especially nonconvex objects, is ex ..."
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Cited by 1 (0 self)
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Abstract. Constraintbased placement tools and their use in diagramming tools has been investigated for decades. One of the most important and natural placement constraints in diagrams is that their graphic elements do not overlap. However, nonoverlap of objects, especially nonconvex objects, is extremely difficult to solve, especially to solve sufficiently rapidly for direct manipulation. Here we present the first practical approach for solving nonoverlap of possibly nonconvex objects in conjunction with other placement constraints such as alignment and distribution. Our methods are based on approximating the nonoverlap constraint by a smoothly changing linear approximation. We have found that this in combination with techniques for lazy addition of constraints, is rapid enough to support direct manipulation in reasonably sized diagrams. 1
Drawing Euler Diagrams from Region Connection Calculus Specifications with local search
"... Abstract. This paper describes a local search based approach and a software tool to approximate the problem of drawing Euler diagrams. Specifications are written using RCC8constraints and radius constraints. Euler diagrams are described as set of circles. 1 ..."
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Abstract. This paper describes a local search based approach and a software tool to approximate the problem of drawing Euler diagrams. Specifications are written using RCC8constraints and radius constraints. Euler diagrams are described as set of circles. 1
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"... XML addresses several HTML shortcomings, but its underdefined processing impedes the development of adequate generic presentation models for the Web. Such models must define the parsing, validation, transformation and rendering of multilanguage XML documents, according to a variety of adaptation re ..."
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XML addresses several HTML shortcomings, but its underdefined processing impedes the development of adequate generic presentation models for the Web. Such models must define the parsing, validation, transformation and rendering of multilanguage XML documents, according to a variety of adaptation requirements. However, most existing approaches only define subsets of this functionality and do not follow the Web design principles. We hypothesise that generic document presentation can be achieved by utilising the presentation domain constraints and addressing the document processing problem as a whole. This thesis focuses on the document preprocessing domain and supports our hypothesis by proposing a preprocessing framework and the XMLPipe preprocessing model. Document preprocessing is the document presentation subset that only addresses parsing, validation and transformation. The preprocessing framework establishes the necessary preprocessing functionality and enables the evaluation of XMLPipe. XMLPipe utilises the presentation domain constraints to provide generic XML preprocessing.
Similarity of Spatial Configurations in Interactive Layout
"... A usability requirement for interactive layout assistance systems is the principle of least astonishment (Borning et al. 1987) which states that the system should arrange the layout in a way that conforms to the user’s expectations. This paper presents a framework for transformationbased similarity ..."
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A usability requirement for interactive layout assistance systems is the principle of least astonishment (Borning et al. 1987) which states that the system should arrange the layout in a way that conforms to the user’s expectations. This paper presents a framework for transformationbased similarity between twodimensional spatial configurations. Here, similarity is intended to measure the user’s expectations when he is presented with a systemside generated layout. The framework is based on results in cognitive science. Firstly, it can serve to validate existing layout algorithms with respect to their ergonomic adequacy. Secondly, it is demonstrated how it can help to design new algorithms respecting the principle of least astonishment. The practical use of the framework is illustrated with UML class diagrams as example domain.