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Mats Carlsson

Swedish Institute of Computer Science, CSL, Faculty Member

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Fernando Zamith

Universidade do Porto

Kostas Zafiropoulos

University of Macedonia

Giovanna Mascheroni

Università Cattolica del Sacro Cuore (Catholic University of the Sacred Heart)

UFMS - Universidade Federal de Mato Grosso do Sul

Francisco Paulo Jamil Marques

The University of Iowa

Utrecht University

Fenwick McKelvey

Concordia University (Canada)

Viacheslav Kuleshov

Stockholm University

Judit Kis-Halas

Eötvös Loránd University Budapest

UFF - Universidade Federal Fluminense

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Papers by Mats Carlsson

The Aurora Or-Parallel Prolog System

by David H D Warren, R. Butler, Rick Stevens, Alan Calderwood, and Mats Carlsson

Joint ERCIM/CoLogNET International Workshop on Constraint Solving and Constraint Logic Programming

Entailment of Finite Domain Constraints

Using a glass-box theory of finite domain constraints, FD, we showhow the entailment of user-defi... more Using a glass-box theory of finite domain constraints, FD, we showhow the entailment of user-defined constraints can be expressed byanti-monotone FD constraints. We also provide an algorithm for checkingthe entailment and consistency of FD constraints. FD is shown tobe expressive enough to allow the definition of arithmetical constraints,as well as non-trivial symbolic constraints, that are normally built in toCLP systems. In particular, we use conditional FD constraints, which...

Sweep as a Generic Pruning Technique Applied to Constraint Relaxation

We introduce a new generic filtering algorithm for handling constraint relaxation within constrai... more We introduce a new generic filtering algorithm for handling constraint relaxation within constraint programming. More prec isely, we first present a generic pruning technique which is useful for a spe cial case of the cardinality operator where all the constraints have at least tw o variables in common. This method is based on a generalization of a sweep algo rithm

Filtrage basØ sur des propriØtØs de graphe

by Mats Carlsson and N. Beldiceanu

Tracing and Explaining Execution of CLP(FD) Programs

by Mats Carlsson and N. Beldiceanu

Computing Research Repository, 2002

Previous work in the area of tracing CLP(FD) programs mainly focuses on providing information abo... more Previous work in the area of tracing CLP(FD) programs mainly focuses on providing information about control of execution and domain modification. In this paper, we present a trace structure that pro- vides information about additional important aspects. We incorporate explanations in the trace structure, i.e. reasons for why certain solver actions occur. Furthermore, we come up with a format for

A New Multi-Resource textttcumulatives Constraint with Negative Heights

by Mats Carlsson and N. Beldiceanu

Sweep synchronisation as a global propagation mechanism

by Mats Carlsson and N. Beldiceanu

Global Constraint Catalog, 2nd Edition (revision a)

by Mats Carlsson and N. Beldiceanu

Graph-Properties Based Filtering. SICS technical report T2006-10

ABSTRACT Graph-Properties Based Filtering

Using Graph Properties for Global Constraints for Necessary Conditions and Filtering

Filtrage basÈ sur des propriÈtÈs de graphes

by Mats Carlsson and N. Beldiceanu

Cet article présente un schéma de filtrage générique, basé sur la description de contraintes glob... more Cet article présente un schéma de filtrage générique, basé sur la description de contraintes globales sous la forme de propriétés de graphes. Cette description est définie par un réseau de contraintes binaires et une liste de propriétés de graphe élémentaires : chaque solution de la contrainte globale correspond à un sous-graphe du réseau initial, dans lequel ne sont retenues que les contraintes binaires satisfaites. Ce sous-graphe doit vérifier les propriétés de graphe qui définissent la contrainte. Le filtrage consiste en l'identification des arcs du réseau qui appartiennent ou non aux sous-graphes solution. L'objectif est de construire, à côté du catalogue de contraintes, une liste de règles de filtrage systématiques. Ces règles sont basées sur un ensemble limité de propriétés. Elles s'appliquent à toutes les contraintes du catalogue décrites à l'aide de ces propriétés. Nous illustrons ce principe sur les propriétés de graphe les plus usuelles, et nous expérimento...

A New Multi-resource cumulatives Constraint with Negative Heights

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2002

Abstract. This paper presents a new,s cumulative constraint which generalizes the original cumula... more Abstract. This paper presents a new,s cumulative constraint which generalizes the original cumulativeconstraint in different ways. The two most importan t aspects consist in permitting multiple cumulative,res ources as well as negative heights for the resource consumption,of the tasks. This allows modeling,in an easy way,new scheduling and planning problems. The introduction of negative heights has forced us to come up

Sweep as a Generic Pruning Technique Applied to the Non-overlapping Rectangles Constraint

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2001

We rst present a generic pruning technique which aggregatesseveral constraints sharing some varia... more We rst present a generic pruning technique which aggregatesseveral constraints sharing some variables. The method is derivedfrom an idea called sweep which is extensively used in computationalgeometry. A rst benet of this technique comes from the fact that itcan be applied on several families of global constraints. A second mainadvantage is that it does not lead to any memory consumption

A Geometric Constraint over k-Dimensional Objects and Shapes Subject to Business Rules

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2008

This report presents a global constraint that enforces rules written in a language based on arith... more This report presents a global constraint that enforces rules written in a language based on arithmetic and first-order logic to hold among a set of objects. In a first step, the rules are rewritten to Quantifier-Free Presburger Arithmetic (QFPA) formulas. Secondly, such formulas are compiled to generators of k-dimensional forbidden sets. Such generators are a generalization of the indexicals of cc(FD). Finally, the forbidden sets generated by such indexicals are aggregated by a sweep-based algorithm and used for filtering. The business rules allow to express a great variety of packing and placement constraints, while admitting efficient and effective filtering of the domain variables of the k-dimensional object, without the need to use spatial data structures. The constraint was used to directly encode the packing knowledge of a major car manufacturer and tested on a set of real packing problems under these rules, as well as on a packing-unpacking problem.

An Integrated Constraint Programming Approach to Scheduling Sports Leagues with Divisional and Round-Robin Tournaments

Lecture Notes in Computer Science, 2014

ABSTRACT Previous approaches for scheduling a league with round-robin and divisional tournaments ... more ABSTRACT Previous approaches for scheduling a league with round-robin and divisional tournaments involved decomposing the problem into easier subproblems. This approach, used to schedule the top Swedish handball league Elitserien, reduces the problem complexity but can result in suboptimal schedules. This paper presents an integrated constraint programming model that allows to perform the scheduling in a single step. Particular attention is given to identifying implied and symmetry-breaking constraints that reduce the computational complexity significantly. The experimental evaluation of the integrated approach takes considerably less computational effort than the previous approach.

Integrating Rule-Based Modelling and Constraint Programming for Solving Industrial Packing Problems

Interfacing engines and schedulers in Or-Parallel Prolog systems

Lecture Notes in Computer Science, 1991

... Prolog Systems P6ter Szeredi; Rong Yang Department of Computer Science University of Bristol,... more

On Matrices, Automata, and Double Counting

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2010

ABSTRACT Matrix models are ubiquitous for constraint problems. Many such problems have a matrix o... more ABSTRACT Matrix models are ubiquitous for constraint problems. Many such problems have a matrix of variables M\mathcal{M}, with the same constraint defined by a finite-state automaton A\mathcal{A} on each row of M\mathcal{M} and a global cardinality constraint gcc{\mathit{gcc}} on each column of M\mathcal{M}. We give two methods for deriving, by double counting, necessary conditions on the cardinality variables of the gcc{\mathit{gcc}} constraints from the automaton A\mathcal{A}. The first method yields linear necessary conditions and simple arithmetic constraints. The second method introduces the cardinality automaton, which abstracts the overall behaviour of all the row automata and can be encoded by a set of linear constraints. We evaluate the impact of our methods on a large set of nurse rostering problem instances.

A Synchronized Sweep Algorithm for the k-dimensional cumulative Constraint

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2013

ABSTRACT This paper presents a sweep based algorithm for the k-dimensional cumulative constraint,... more ABSTRACT This paper presents a sweep based algorithm for the k-dimensional cumulative constraint, which can operate in filtering mode as well as in greedy assignment mode. Given n tasks and k resources, this algorithm has a worst-case time complexity of O(kn 2) but scales well in practice. In greedy assignment mode, it handles up to 1 million tasks with 64 resources in one single constraint in SICStus. In filtering mode, on our benchmarks, it yields a speed-up of about k 0.75 when compared to its decomposition into k independent cumulative constraints.

The Aurora Or-Parallel Prolog System

by David H D Warren, R. Butler, Rick Stevens, Alan Calderwood, and Mats Carlsson

Joint ERCIM/CoLogNET International Workshop on Constraint Solving and Constraint Logic Programming

Entailment of Finite Domain Constraints

Using a glass-box theory of finite domain constraints, FD, we showhow the entailment of user-defi... more Using a glass-box theory of finite domain constraints, FD, we showhow the entailment of user-defined constraints can be expressed byanti-monotone FD constraints. We also provide an algorithm for checkingthe entailment and consistency of FD constraints. FD is shown tobe expressive enough to allow the definition of arithmetical constraints,as well as non-trivial symbolic constraints, that are normally built in toCLP systems. In particular, we use conditional FD constraints, which...

Sweep as a Generic Pruning Technique Applied to Constraint Relaxation

We introduce a new generic filtering algorithm for handling constraint relaxation within constrai... more We introduce a new generic filtering algorithm for handling constraint relaxation within constraint programming. More prec isely, we first present a generic pruning technique which is useful for a spe cial case of the cardinality operator where all the constraints have at least tw o variables in common. This method is based on a generalization of a sweep algo rithm

Filtrage basØ sur des propriØtØs de graphe

by Mats Carlsson and N. Beldiceanu

Tracing and Explaining Execution of CLP(FD) Programs

by Mats Carlsson and N. Beldiceanu

Computing Research Repository, 2002

Previous work in the area of tracing CLP(FD) programs mainly focuses on providing information abo... more Previous work in the area of tracing CLP(FD) programs mainly focuses on providing information about control of execution and domain modification. In this paper, we present a trace structure that pro- vides information about additional important aspects. We incorporate explanations in the trace structure, i.e. reasons for why certain solver actions occur. Furthermore, we come up with a format for

A New Multi-Resource textttcumulatives Constraint with Negative Heights

by Mats Carlsson and N. Beldiceanu

Sweep synchronisation as a global propagation mechanism

by Mats Carlsson and N. Beldiceanu

Global Constraint Catalog, 2nd Edition (revision a)

by Mats Carlsson and N. Beldiceanu

Graph-Properties Based Filtering. SICS technical report T2006-10

ABSTRACT Graph-Properties Based Filtering

Using Graph Properties for Global Constraints for Necessary Conditions and Filtering

Filtrage basÈ sur des propriÈtÈs de graphes

by Mats Carlsson and N. Beldiceanu

Cet article présente un schéma de filtrage générique, basé sur la description de contraintes glob... more Cet article présente un schéma de filtrage générique, basé sur la description de contraintes globales sous la forme de propriétés de graphes. Cette description est définie par un réseau de contraintes binaires et une liste de propriétés de graphe élémentaires : chaque solution de la contrainte globale correspond à un sous-graphe du réseau initial, dans lequel ne sont retenues que les contraintes binaires satisfaites. Ce sous-graphe doit vérifier les propriétés de graphe qui définissent la contrainte. Le filtrage consiste en l'identification des arcs du réseau qui appartiennent ou non aux sous-graphes solution. L'objectif est de construire, à côté du catalogue de contraintes, une liste de règles de filtrage systématiques. Ces règles sont basées sur un ensemble limité de propriétés. Elles s'appliquent à toutes les contraintes du catalogue décrites à l'aide de ces propriétés. Nous illustrons ce principe sur les propriétés de graphe les plus usuelles, et nous expérimento...

A New Multi-resource cumulatives Constraint with Negative Heights

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2002

Abstract. This paper presents a new,s cumulative constraint which generalizes the original cumula... more Abstract. This paper presents a new,s cumulative constraint which generalizes the original cumulativeconstraint in different ways. The two most importan t aspects consist in permitting multiple cumulative,res ources as well as negative heights for the resource consumption,of the tasks. This allows modeling,in an easy way,new scheduling and planning problems. The introduction of negative heights has forced us to come up

Sweep as a Generic Pruning Technique Applied to the Non-overlapping Rectangles Constraint

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2001

We rst present a generic pruning technique which aggregatesseveral constraints sharing some varia... more We rst present a generic pruning technique which aggregatesseveral constraints sharing some variables. The method is derivedfrom an idea called sweep which is extensively used in computationalgeometry. A rst benet of this technique comes from the fact that itcan be applied on several families of global constraints. A second mainadvantage is that it does not lead to any memory consumption

A Geometric Constraint over k-Dimensional Objects and Shapes Subject to Business Rules

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2008

This report presents a global constraint that enforces rules written in a language based on arith... more This report presents a global constraint that enforces rules written in a language based on arithmetic and first-order logic to hold among a set of objects. In a first step, the rules are rewritten to Quantifier-Free Presburger Arithmetic (QFPA) formulas. Secondly, such formulas are compiled to generators of k-dimensional forbidden sets. Such generators are a generalization of the indexicals of cc(FD). Finally, the forbidden sets generated by such indexicals are aggregated by a sweep-based algorithm and used for filtering. The business rules allow to express a great variety of packing and placement constraints, while admitting efficient and effective filtering of the domain variables of the k-dimensional object, without the need to use spatial data structures. The constraint was used to directly encode the packing knowledge of a major car manufacturer and tested on a set of real packing problems under these rules, as well as on a packing-unpacking problem.

An Integrated Constraint Programming Approach to Scheduling Sports Leagues with Divisional and Round-Robin Tournaments

Lecture Notes in Computer Science, 2014

ABSTRACT Previous approaches for scheduling a league with round-robin and divisional tournaments ... more ABSTRACT Previous approaches for scheduling a league with round-robin and divisional tournaments involved decomposing the problem into easier subproblems. This approach, used to schedule the top Swedish handball league Elitserien, reduces the problem complexity but can result in suboptimal schedules. This paper presents an integrated constraint programming model that allows to perform the scheduling in a single step. Particular attention is given to identifying implied and symmetry-breaking constraints that reduce the computational complexity significantly. The experimental evaluation of the integrated approach takes considerably less computational effort than the previous approach.

Integrating Rule-Based Modelling and Constraint Programming for Solving Industrial Packing Problems

Interfacing engines and schedulers in Or-Parallel Prolog systems

Lecture Notes in Computer Science, 1991

... Prolog Systems P6ter Szeredi; Rong Yang Department of Computer Science University of Bristol,... more

On Matrices, Automata, and Double Counting

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2010

ABSTRACT Matrix models are ubiquitous for constraint problems. Many such problems have a matrix o... more ABSTRACT Matrix models are ubiquitous for constraint problems. Many such problems have a matrix of variables M\mathcal{M}, with the same constraint defined by a finite-state automaton A\mathcal{A} on each row of M\mathcal{M} and a global cardinality constraint gcc{\mathit{gcc}} on each column of M\mathcal{M}. We give two methods for deriving, by double counting, necessary conditions on the cardinality variables of the gcc{\mathit{gcc}} constraints from the automaton A\mathcal{A}. The first method yields linear necessary conditions and simple arithmetic constraints. The second method introduces the cardinality automaton, which abstracts the overall behaviour of all the row automata and can be encoded by a set of linear constraints. We evaluate the impact of our methods on a large set of nurse rostering problem instances.

A Synchronized Sweep Algorithm for the k-dimensional cumulative Constraint

by Mats Carlsson and N. Beldiceanu

Lecture Notes in Computer Science, 2013

ABSTRACT This paper presents a sweep based algorithm for the k-dimensional cumulative constraint,... more ABSTRACT This paper presents a sweep based algorithm for the k-dimensional cumulative constraint, which can operate in filtering mode as well as in greedy assignment mode. Given n tasks and k resources, this algorithm has a worst-case time complexity of O(kn 2) but scales well in practice. In greedy assignment mode, it handles up to 1 million tasks with 64 resources in one single constraint in SICStus. In filtering mode, on our benchmarks, it yields a speed-up of about k 0.75 when compared to its decomposition into k independent cumulative constraints.