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Using constraint Programming in Selection Operators for constraint databases

EXPERT SYSTEMS WITH APPLICATIONS 2014年第15期41卷 6773-6785页

作者： Teresa Gomez-Lopez, Maria Gasca, Rafael M. Univ Seville Dept Languages & Comp Syst Seville Spain

constraint databases represent complex data by means of formulas described by constraints (equations, inequations or Boolean combinations of both). Commercial database management systems allow the storage and efficient retrieval of classic data, but for complex data a made-to-measure solution combined with expert systems for each type of problem are necessary. Therefore, in the same way as commercial solutions of relational databases permit storing and querying classic data, we propose an extension of the Selection Operator for complex data stored, and an extension of SQL language for the case where both classic and constraint data need to be managed. This extension shields the user from unnecessary details on how the information is stored and how the queries are evaluated, thereby enlarging the capacity of expressiveness for any commercial database management system. In order to minimize the selection time, a set of strategies have been proposed, which combine the advantages of relational algebra and constraint data representation. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Complex data Optimal query evaluation Selection Operator constraint databases constraint Programming

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Efficient evaluation of specific queries in constraint databases

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INFORMATION PROCESSING LETTERS 2011年第19期111卷 941-944页

作者： Grimson, Rafael Heintz, Joos Kuijpers, Bart Univ Buenos Aires Fac Ciencias Exactas & Nat Dept Comp RA-1428 Buenos Aires DF Argentina Univ Buenos Aires Fac Ciencias Exactas & Nat Dept Matemat RA-1428 Buenos Aires DF Argentina Consejo Nacl Invest Cient & Tecn RA-1428 Buenos Aires DF Argentina Univ Cantabria Fac Ciencias Dept Matemat Estadist & Comp Santander 39071 Spain Hasselt Univ Database & Theoret Comp Sci Res Grp B-3590 Diepenbeek Belgium

Let F(1),...,F(s) is an element of R[X(1),...,X(n)] be polynomials of degree at most d, and suppose that F(1),...,F(s) are represented by a division free arithmetic circuit of non-scalar complexity size L. Let A be the arrangement of R(n) defined by F(1),...,F(s). For any point x is an element of R(n), we consider the task of determining the signs of the values F(1)(x),...,F(s)(x) (sign condition query) and the task of determining the connected component of A to which x belongs (point location query). By an extremely simple reduction to the well-known case where the polynomials F1,...,Fs are affine linear (i.e., polynomials of degree one), we show first that there exists a database of (possibly enormous) size s(O(L+n)) which allows the evaluation of the sign condition query using only (Ln)(O(1)) log(s) arithmetic operations. The key point of this paper is the proof that this upper bound is almost optimal. By the way, we show that the point location query can be evaluated using d(O(n)) log(s) arithmetic operations. Based on a different argument, analogous complexity upper-bounds are exhibited with respect to the bit-model in case that F(1),...,F(s) belong to Z[X(1),...,X(n)] and satisfy a certain natural genericity condition. Mutatis mutandis our upper-bound results may be applied to the sparse and dense representations of F(1),...,F(s). (C) 2011 Elsevier B.V. All rights reserved.

关键词： constraint databases Query evaluation Computational complexity

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The 3D motion of a solid with large deformations

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COMPTES RENDUS MATHEMATIQUE 2014年第3期352卷 183-187页

作者： Bonetti, Elena Colli, Pierluigi Fremond, Michel Univ Pavia Dipartimento Matemat F Casorati Lab Lagrange I-27100 Pavia Italy Univ Roma Tor Vergata Dipartimento Ingn Civile Lab Lagrange I-00133 Rome Italy

We study in dimension 3 the motion of a solid with large deformations. The solid may be loaded on its surface by needles, rods, beams, shells, etc. Therefore, it is wise to choose a third gradient theory for the body. It is known that the stretch matrix of the polar decomposition has to be symmetric. This is an internal constraint, which introduces a reaction stress in the Piola-Kirchhoff-Boussinesq stress. We prove that there exists a motion that satisfies the complete equations of Mechanics in a convenient variational framework. This motion is local-in-time for it may be interrupted by a crushing, which entails a discontinuity of velocity with respect to time, i.e., an internal collision. (C) 2014 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

关键词： DEFORMATIONS (Mechanics) SOLID state physics SYMMETRY (Mathematics) constraint databases VARIATIONAL principles

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Benchmarking curriculum-based course timetabling: formulations, data formats, instances, validation, visualization, and results

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ANNALS OF OPERATIONS RESEARCH 2012年第1期194卷 59-70页

作者： Bonutti, Alex De Cesco, Fabio Di Gaspero, Luca Schaerf, Andrea Univ Udine DIEGM I-33100 Udine Italy EasyStaff Srl I-33100 Udine Italy

We propose a set of formulations for the Curriculum-Based Course Timetabling problem, with the aim of "capturing" many real-world formulations, and thus encouraging researchers to "reduce" their specific problems to one of them, gaining the opportunity to compare and assess their results. This work is accompanied by a web application that maintains all the necessary infrastructures for benchmarking: validators, data formats, instances, reference scores, lower bounds, solutions, and visualizers. All instances proposed here are based on real data from various universities and they represent a variety of possible situations.

关键词： TIME perspective EDUCATION benchmarking EDUCATIONAL innovations INFORMATION visualization constraint databases

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An analytic solution to the alibi query in the space-time prisms model for moving object data

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INTERNATIONAL JOURNAL OF GEOGRAPHICAL INFORMATION SCIENCE 2011年第2期25卷 293-322页

作者： Kuijpers, Bart Grimson, Rafael Othman, Walied Hasselt Univ Database & Theoret Comp Sci Res Grp Diepenbeek Belgium

Moving objects produce trajectories, which are stored in databases by means of finite samples of time-stamped locations. When speed limitations in these sample points are also known, space-time prisms (also called beads) (Pfoser and Jensen 1999, Egenhofer 2003, Miller 2005) can be used to model the uncertainty about an object's location in between sample points. In this setting, a query of particular interest that has been studied in the literature of geographic information systems (GIS) is the alibi query. This boolean query asks whether two moving objects could have physically met. This adds up to deciding whether the chains of space-time prisms (also called necklaces of beads) of these objects intersect. This problem can be reduced to deciding whether two space-time prisms intersect. The alibi query can be seen as a constraint database query. In the constraint database model, spatial and spatiotemporal data are stored by boolean combinations of polynomial equalities and inequalities over the real numbers. The relational calculus augmented with polynomial constraints is the standard first-order query language for constraint databases and the alibi query can be expressed in it. The evaluation of the alibi query in the constraint database model relies on the elimination of a block of three existential quantifiers. Implementations of general purpose elimination algorithms, such as those provided by QEPCAD, Redlog, and Mathematica, are, for practical purposes, too slow in answering the alibi query for two specific space-time prisms. These software packages completely fail to answer the alibi query in the parametric case (i.e., when it is formulated in terms of parameters representing the sample points and speed constraints). The main contribution of this article is an analytical solution to the parametric alibi query, which can be used to answer the alibi query on two specific space-time prisms in constant time (a matter of milliseconds in our implementation). It solv

关键词： uncertainty space-time prism alibi query spatiotemporal constraint databases moving objects

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Trajectory databases: Data models, uncertainty and complete query languages

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JOURNAL OF COMPUTER AND SYSTEM SCIENCES 2010年第7期76卷 538-560页

作者： Kuijpers, Bart Othman, Walied Hasselt Univ Dept Math Phys & Comp Sci B-3590 Diepenbeek Belgium Transnatl Univ Limburg Limburg Belgium

Moving objects produce trajectories. We describe a data model for trajectories and trajectory samples and an efficient way of modeling uncertainty via beads for trajectory samples. We study transformations of the ambient space for which important physical properties of trajectories, such as speed, are invariant. We also determine which transformations preserve beads. We give conceptually easy first-order complete query languages and computationally complete query languages for trajectory databases, which allow to talk directly about speed and uncertainty in terms of beads. The queries expressible in these languages are invariant under speed- and bead-preserving transformations. (C) 2009 Elsevier Inc. All rights reserved.

关键词： Moving objects databases Spatio-temporal databases constraint databases Trajectories Trajectory samples Beads Uncertainty

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Uniform generation in spatial constraint databases and applications

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JOURNAL OF COMPUTER AND SYSTEM SCIENCES 2006年第4期72卷 576-591页

作者： Gross-Amblard, David de Rougemont, Michel Conservatoire Natl Arts & Metiers Equipe Vertigo Lab CEDRIC Special Informat CC 432 F-75141 Paris 03 France Univ Paris 02 F-91405 Orsay France Univ Paris 11 LRI F-91405 Orsay France

We study the efficient approximation of queries in linear constraint databases using sampling techniques. We define the notion of an almost uniform generator for a generalized relation and extend the classical generator of Dyer, Frieze and Karman for convex sets to the union and the projection of relations. For the intersection and the difference, we give sufficient conditions for the existence of such generators. We show how such generators give relative estimations of the volume and approximations of generalized relations as the composition of convex hulls obtained from the samples. (C) 2005 Elsevier Inc. All rights reserved.

关键词： constraint databases approximation estimator generator sampling volume dimension

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IMPROVING THE DETERMINATION OF MINIMAL HITTING SETS IN MODEL-BASED DIAGNOSIS USING constraint databases

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IFAC Proceedings Volumes 2006年第13期39卷 1509-1514页

作者： M.T. Gómez-López R.M. Gasca C. del Valle Escuela Técnica y Superior de Ingeniería Informática de Sevilla Spain

In model-based diagnosis, minimal hitting sets are usually used to identify which components may fail in a system. This work presents a set of algorithms to improve the determination of all Minimal Hitting Sets. Our proposal uses the minimal conflict sets to obtain, in an efficient way, the diagnosis of a system. The improvement consists of three algorithms which analyse only the relevant options. This proposal builds an equivalent system in order to obtain all minimal hitting sets depending on the location of the sensors. At the same time, all the information of the process is stored in a constraint Database, keeping the information persistent and recoverable. Some empirical results are presented in order to show how the proposal improves the process in order to obtain all minimal hitting sets.

关键词： Model-based Diagnosis constraint databases minimal hitting sets

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On the decidability of termination of query evaluation in transitive-closure logics for polynomial constraint databases

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THEORETICAL COMPUTER SCIENCE 2005年第1期336卷 125-151页

作者： Geerts, F Kuijpers, B Limburgs Univ Ctr Dept WNI Dept Math Phys & Comp Sci B-3590 Diepenbeek Belgium Helsinki Inst Informat Technol Basic Res Unit Helsinki Finland

The formalism of constraint databases, in which possibly infinite data sets are described by Boolean combinations of polynomial inequality and equality constraints, has its main application area in spatial databases. The standard query language for polynomial constraint databases is first-order logic over the reals. Because of the limited expressive power of this logic with respect to queries that are important in spatial data base applications, various extensions have been introduced. We study extensions of first-order logic with different types of transitive-closure operators and we are in particular interested in deciding the termination of the evaluation of queries expressible in these transitive-closure logics. lt turns out that termination is undecidable in general. However, we show that the termination of the transitive closure of a continuous function graph in the two-dimensional plane, viewed as a binary relation over the reals, is decidable, and even expressible in first-order logic over the reals. Based on this result, we identify a particular transitive-closure logic for which termination of query evaluation is decidable and which is more expressive than first-order logic over the reals. Furthermore, we can define a guarded fragment in which exactly the terminating queries of this language are expressible. (c) 2004 Elsevier B.V. All rights reserved.

关键词： data base theory constraint databases query languages query evaluation dynamical systems theory fixed points

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On the decidability of termination of query evaluation in transitive-closure logics for polynomial constraint databases

On the decidability of termination of query evaluation in tr...

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9th International Conference on Database Theory (ICDT)

作者： Geerts, F Kuijpers, B Limburgs Univ Ctr Dept WNI Dept Math Phys & Comp Sci B-3590 Diepenbeek Belgium Helsinki Inst Informat Technol Basic Res Unit Helsinki Finland

关键词： data base theory constraint databases query languages query evaluation dynamical systems theory fixed points

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