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43
Fixedparameter algorithms for artificial intelligence, constraint satisfaction, and database problems
, 2007
"... We survey the parameterized complexity of problems that arise in artificial intelligence, database theory and automated reasoning. In particular, we consider various parameterizations of the constraint satisfaction problem, the evaluation problem of Boolean conjunctive database queries and the propo ..."
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Cited by 31 (10 self)
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We survey the parameterized complexity of problems that arise in artificial intelligence, database theory and automated reasoning. In particular, we consider various parameterizations of the constraint satisfaction problem, the evaluation problem of Boolean conjunctive database queries and the propositional satisfiability problem. Furthermore, we survey parameterized algorithms for problems arising in the context of the stable model semantics of logic programs, for a number of other problems of nonmonotonic reasoning, and for the computation of cores in data exchange.
Sudoku as a SAT problem
 In Proc. of the Ninth International Symposium on Artificial Intelligence and Mathematics
, 2006
"... Sudoku is a very simple and wellknown puzzle that has achieved international popularity in the recent past. This paper addresses the problem of encoding Sudoku puzzles into conjunctive normal form (CNF), and subsequently solving them using polynomialtime propositional satisfiability (SAT) inferenc ..."
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Cited by 25 (0 self)
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Sudoku is a very simple and wellknown puzzle that has achieved international popularity in the recent past. This paper addresses the problem of encoding Sudoku puzzles into conjunctive normal form (CNF), and subsequently solving them using polynomialtime propositional satisfiability (SAT) inference techniques. We introduce two straightforward SAT encodings for Sudoku: the minimal encoding and the extended encoding. The minimal encoding suffices to characterize Sudoku puzzles, whereas the extended encoding adds redundant clauses to the minimal encoding. Experimental results demonstrate that, for thousands of very hard puzzles, inference techniques struggle to solve these puzzles when using the minimal encoding. However, using the extended encoding, unit propagation is able to solve about half of our set of puzzles. Nonetheless, for some puzzles more sophisticated inference techniques are required. 1
Constructive Interval Disjunction
 In Proc. CP, LNCS 4741
, 2007
"... Abstract. This paper presents two new filtering operators for numerical CSPs (systems with constraints over the reals) based on constructive disjunction, as well as a new splitting heuristic. The fist operator (CID) isa generic algorithm enforcing constructive disjunction with intervals. The second ..."
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Cited by 20 (17 self)
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Abstract. This paper presents two new filtering operators for numerical CSPs (systems with constraints over the reals) based on constructive disjunction, as well as a new splitting heuristic. The fist operator (CID) isa generic algorithm enforcing constructive disjunction with intervals. The second one (3BCID) is a hybrid algorithm mixing constructive disjunction and shaving, another technique already used with numerical CSPs through the algorithm 3B. Finally, the splitting strategy learns from the CID filtering step the next variable to be split, with no overhead. Experiments have been conducted with 20 benchmarks. On several benchmarks, CID and 3BCID produce a gain in performance of orders of magnitude over a standard strategy. CID compares advantageously to the 3B operator while being simpler to implement. Experiments suggest to fix the CIDrelated parameter in 3BCID, offering thus to the user a promising variant of 3B. 1
The impact of balancing on problem hardness in a highly structured domain
 Proc. of 9th International Conference on Theory and Applications of Satisfiability Testing (SAT ’06
, 2006
"... Random problem distributions have played a key role in the study and design of algorithms for constraint satisfaction and Boolean satisfiability, as well as in our understanding of problem hardness, beyond standard worstcase complexity. We consider random problem distributions from a highly structu ..."
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Cited by 7 (2 self)
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Random problem distributions have played a key role in the study and design of algorithms for constraint satisfaction and Boolean satisfiability, as well as in our understanding of problem hardness, beyond standard worstcase complexity. We consider random problem distributions from a highly structured problem domain that generalizes the Quasigroup Completion problem (QCP) and Quasigroup with Holes (QWH), a widely used domain that captures the structure underlying a range of realworld applications. Our problem domain is also a generalization of the wellknown Sudoku puzzle: we consider Sudoku instances of arbitrary order, with the additional generalization that the block regions can have rectangular shape, in addition to the standard square shape. We evaluate the computational hardness of Generalized Sudoku instances, for different parameter settings. Our experimental hardness results show that we can generate instances that are considerably harder than QCP/QWH instances of the same size. More interestingly, we show the impact of different balancing strategies on problem hardness. We also provide insights into backbone variables in Generalized Sudoku instances and how they correlate to problem hardness.
The graph grammar library  a generic framework for chemical graph rewrite systems
 Theory and Practice of Model Transformations, Proc. of ICMT 2013, volume 7909 of LNCS
, 2013
"... Abstract. Graph rewrite systems are powerful tools to model and study complex problems in various fields of research. Their successful application to chemical reaction modelling on a molecular level was shown but no appropriate and simple system is available at the moment. The presented Graph Gramma ..."
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Cited by 6 (3 self)
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Abstract. Graph rewrite systems are powerful tools to model and study complex problems in various fields of research. Their successful application to chemical reaction modelling on a molecular level was shown but no appropriate and simple system is available at the moment. The presented Graph Grammar Library (GGL) implements a generic Double Push Out approach for general graph rewrite systems. The framework focuses on a high level of modularity as well as high performance, using stateoftheart algorithms and data structures, and comes with extensive documentation. The large GGL chemistry module enables extensive and detailed studies of chemical systems. It well meets the requirements and abilities envisioned by Yadav et al. (2004) for such chemical rewrite systems. Here, molecules are represented as undirected labeled graphs while chemical reactions are described by according graph grammar rules. Beside the graph transformation, the GGL offers advanced cheminformatics algorithms for instance to estimate energies ofmolecules or aromaticity perception. These features are illustrated using a set of reactions from polyketide chemistry a huge class of natural compounds of medical relevance. The graph grammar based simulation of chemical reactions offered by the GGL is a powerful tool for extensive cheminformatics studies on a molecular level. The GGL already provides rewrite rules for all enzymes listed in the KEGG LIGAND database is freely available at
Farion, K.: Identifying inconsistencies in multiple clinical practice guidelines for a patient with comorbidity
 In: Proceedings of KEDDH10
, 2010
"... Abstract — This paper describes a methodological approach to identifying inconsistencies when reconciling multiple clinical practice guidelines. The need to address these inconsistencies arises when a patient with comorbidity has to be managed according to different treatment regimens. Starting wit ..."
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Cited by 5 (4 self)
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Abstract — This paper describes a methodological approach to identifying inconsistencies when reconciling multiple clinical practice guidelines. The need to address these inconsistencies arises when a patient with comorbidity has to be managed according to different treatment regimens. Starting with a wellknown flowchart representation we discuss how to create a formal guideline model that allows for easy manipulations of its components. For this model we present how to identify conflicting actions that are manifested by treatmenttreatment and treatmentdisease interactions, and how to reconcile these conflicting actions. I.
Difficulty Rating of Sudoku Puzzles by a Computational Model ∗
"... We discuss and evaluate metrics for difficulty rating of Sudoku puzzles. The correlation coefficient with human performance for our best metric is 0.95. The data on human performance were obtained from three web portals and they comprise thousands of hours of human solving over 2000 problems. We pro ..."
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Cited by 5 (2 self)
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We discuss and evaluate metrics for difficulty rating of Sudoku puzzles. The correlation coefficient with human performance for our best metric is 0.95. The data on human performance were obtained from three web portals and they comprise thousands of hours of human solving over 2000 problems. We provide a simple computational model of human solving activity and evaluate it over collected data. Using the model we show that there are two sources of problem difficulty: complexity of individual steps (logic operations) and structure of dependency among steps. Beside providing a very good Sudokutuned metric, we also discuss a metric with few Sudokuspecific details, which still provides good results (correlation coefficient is 0.88). Hence we believe that the approach should be applicable to difficulty rating of other constraint satisfaction problems.
Comparing ASP and CP on Four Grid Puzzles
"... We study two declarative programming languages namely Answer Set Programming (ASP) and Constraint Programming (CP) on four grid puzzles: Akari, Kakuro, Nurikabe, and Heyawake. We represent these problems in both formalisms in a systematic way and compute their solutions using ASP system Clasp and CP ..."
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Cited by 4 (0 self)
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We study two declarative programming languages namely Answer Set Programming (ASP) and Constraint Programming (CP) on four grid puzzles: Akari, Kakuro, Nurikabe, and Heyawake. We represent these problems in both formalisms in a systematic way and compute their solutions using ASP system Clasp and CP system Comet. We compare the ASP approach with the CP approach both from the point of view of knowledge representation and from the point of view of computational time and memory. 1
Human Problem Solving: Sudoku Case Study
, 2011
"... is permitted for educational or research use on condition that this copyright notice is included in any copy. Publications in the FI MU Report Series are in general accessible via WWW: ..."
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Cited by 3 (1 self)
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is permitted for educational or research use on condition that this copyright notice is included in any copy. Publications in the FI MU Report Series are in general accessible via WWW: