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Daniel Berre

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Roberto Confalonieri

Juan Carlos Nieves

Universitat Politecnica de Catalunya

Universidad Politécnica de Madrid

Arizona State University

Roberto Confalonieri

CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council)

Carlos Iván Chesñevar

Universidad Nacional del Sur

Guillermo R. Simari

Marcelo Falappa

Nick Bassiliades

Aristotle University of Thessaloniki

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Papers by Daniel Berre

Qualitative Choice Logic

Kr, 2002

Qualitative choice logic (QCL) is a propositional logic for representing alternative, ranked opti... more Qualitative choice logic (QCL) is a propositional logic for representing alternative, ranked options for problem solutions. The logic adds to classical propositional logic a new connective called ordered disjunction: A × B intuitively means: if possible A, but if A is not possible then at least B. The semantics of qualitative choice logic is based on a preference relation among models. Consequences of QCL theories can be computed through a compilation to stratified knowledge bases which in turn can be compiled to classical propositional theories. We also discuss potential applications of the logic, several variants of QCL based on alternative inference relations, and their relation to existing nonmonotonic formalisms. 1

Comparing Arguments Using Preference Orderings for Argument-Based Reasoning

Proceedings of the 8th International Conference on Tools With Artificial Intelligence, Nov 16, 1996

Abstract Argument-based reasoning is a promising approach to handle inconsistent belief bases. Th... more

Logical Representation and Computation of Optimal Decisions in a Qualitative Setting

Aaai, 1998

This paper describes a logical machinery for computing decisions based on an ATMS procedure, wher... more This paper describes a logical machinery for computing decisions based on an ATMS procedure, where the available knowledge on the state of the world is described by a possibilistic propositional logic base (i.e., a collection of logical statements associated with qualitative certainty levels). The preferences of the user are also described by another possibilistic logic base whose formula weights are interpreted in terms of priorities and formulas express goals. Two attitudes are allowed for the decision maker: a pessimistic uncertainty-averse one and an optimistic one. The computed decisions are in agreement with a qualitative counterpart to classical expected utility theory for decision under uncertainty.

Complexity Results for Quantified Boolean Formulae Based on Complete Propositional Languages ∗ Sylvie Coste-Marquis

Several propositional fragments have been considered so far as target languages for knowledge com... more Several propositional fragments have been considered so far as target languages for knowledge compilation and used for improving computational tasks from major AI areas (like inference, diagnosis and planning); among them are the ordered binary decision diagrams, prime implicates, prime implicants, "formulae" in decomposable negation normal form. On the other hand, the validity problem val(QPROP P S ) for Quantified Boolean Formulae (QBF) has been acknowledged for the past few years as an important issue for AI, and many solvers have been designed. In this paper, the complexity of restrictions of the validity problem for QBF obtained by imposing the matrix of the input QBF to belong to propositional fragments used as target languages for compilation, is identified. It turns out that this problem remains hard (PSPACE-complete) even under severe restrictions on the matrix of the input. Nevertheless some tractable restrictions are pointed out.

$Figure 2. A formula in NNF pg. On the left part, the node marked *\ is decomposable while the node marked with the same symbol on the right part denotes a deterministic and smooth node.$

Using the Davis and Putnam Procedure for an Efficient Computation of Preferred Models

Ecai, 1996

Some famous problems (ATMS inference, ClosedWorld Reasoning (CWR) for instance) can be replaced b... more Some famous problems (ATMS inference, ClosedWorld Reasoning (CWR) for instance) can be replaced by aproblem of preferred model computation. We thus propose apreference relation between models based on a preference relationbetween literals and an &amp;amp;amp;amp;amp;amp;amp;amp;quot;efficient&amp;amp;amp;amp;amp;amp;amp;amp;quot; algorithm to computethe associated preferred models of a theory. Then, we applythis algorithm to ATMS inference and problems of CWR.Sub-problems like subsumption and label computation

An Alternative Inference for Qualitative Choice Logic

European Conference on Artificial Intelligence, 2006

The Sat4j library, release 2.2

Sat4j is a mature, open source library of SAT-based solvers in Java. It provides a modular SAT so... more Sat4j is a mature, open source library of SAT-based solvers in Java. It provides a modular SAT solver architecture designed to work with generic constraints. Such architecture is used to provide SAT, MaxSat and pseudo-boolean and solvers for lightweight constraint programming. Those solvers have been evaluated regularly in the corresponding international competitive events. The library has been adopted by several academic softwares and the widely used Eclipse platform, which relies on a pseudo-boolean solver from Sat4j for its plugins dependencies management since June 2008.

Challenges in the QBF Arena: the SAT’03 Evaluation of QBF Solvers

Lecture Notes in Computer Science, 2004

The implementation of effective reasoning tools for deciding the satisfiability of Quantified Boo... more The implementation of effective reasoning tools for deciding the satisfiability of Quantified Boolean Formulas (QBFs) is an important issue in several research fields such as Formal Verification, Planning, and Reasoning about Knowledge. Several QBF solvers have been implemented in the last few years, most of them extending the well-known Davis, Putnam, Logemann, Loveland procedure (DPLL) for propositional satisfiability (SAT). At the same time, a substantial breed of QBF benchmarks emerged, both in the form of statistical models for the generation of random formulas, and in the form of real-world instances. In this paper we report about the -first ever -evaluation of QBF solvers that was run as a joint event to SAT'03 Conference on Theory and Applications of Satisfiability Testing. Owing to the relative youngness of QBF tools and applications, we decided to run the comparison on a non-competitive basis, using the same technology that powered SAT'02 and SAT'03 competitions of SAT solvers. Running the evaluation enabled us to collect all sorts of data regarding the relative strength of different solvers and methods, the quality of the benchmarks, and to understand some of the current challenges for researchers involved in the QBF arena.

The Second QBF Solvers Comparative Evaluation

Lecture Notes in Computer Science, 2005

This paper reports about the 2004 comparative evaluation of solvers for quantified Boolean formul... more This paper reports about the 2004 comparative evaluation of solvers for quantified Boolean formulas (QBFs), the second in a series of non-competitive events established with the aim of assessing the advancements in the field of QBF reasoning and related research. We evaluated sixteen solvers on a test set of about one thousand benchmarks, selected from instances submitted to the evaluation and from those available at www.qbflib.org. In the paper we present the evaluation infrastructure, from the criteria used to select the benchmarks to the hardware set up, and we show different views about the results obtained, highlighting the strength of different solvers and the relative hardness of the benchmarks included in the test set.

The Essentials of the SAT 2003 Competition

Lecture Notes in Computer Science, 2004

The SAT 2003 Competition ran in February -May 2003, in conjunction with SAT'03 (the Sixth Fifth I... more The SAT 2003 Competition ran in February -May 2003, in conjunction with SAT'03 (the Sixth Fifth International Symposium on the Theory and Applications of Satisfiability Testing). One year after the SAT 2002 competition, it was not clear that significant progress could be made in the area in such a little time. The competition was a success -34 solvers and 993 benchmarks, needing 522 CPU days -with a number of brand new solvers. Several 2003 competitors were even able to solve within 15mn benchmarks remained unsolved within 6 hours by 2002 competitors. We report here the essential results of the competition, interpret and statistically analyse them, and at last provide some suggestions for the future competitions. sato (release 3.4) from Hantao Zhang . satzilla (release 0.9, v1 v2 v2-fixed) (v2s are hors concours) from Kevin Leyton-Brown, . Authors asked us to consider a new version of satzilla2. They discovered, during the contest, that satzilla2 had bugs in its learning phase, that led to wrong choices of solvers during the contest. The new version is refered as satzilla2-fixed. satzoo (release 0.98 v0 v1) from Niklas Een . tts (ternary tree solver, release 1.0, hors concours) from Ivor Spence. zchaff from Yinlei Yu and Lintao Zhang . zchaff was awarded best complete solver for both industrial and handmade categories at SAT'02 competition.

Aggregating Interval Orders by Propositional Optimization

Lecture Notes in Computer Science, 2009

Abstract. Aggregating preferences for findinga consensus between several agents is an important i... more Abstract. Aggregating preferences for findinga consensus between several agents is an important issue in many fields, like economics, decision theory and artificial intelligence. In this paper we focus on the problem of aggregating interval orders which are special preference structures allowing the introduction of tresholds for the indifference relation. We propose to solve this problem,by first translating it into a

On the Complexity of Optimization Problems based on Compiled NNF Representations

by Emmanuel Lonca and Daniel Berre

Optimization is a key task in a number of applications. When the set of feasible solutions under ... more Optimization is a key task in a number of applications. When the set of feasible solutions under consideration is of combinatorial nature and described in an implicit way as a set of constraints, optimization is typically NP-hard. Fortunately, in many problems, the set of feasible solutions does not often change and is independent from the user's request. In such cases, compiling the set of constraints describing the set of feasible solutions during an off-line phase makes sense, if this compilation step renders computationally easier the generation of a non-dominated, yet feasible solution matching the user's requirements and preferences (which are only known at the on-line step). In this article, we focus on propositional constraints. The subsets L of the NNF language analyzed in Darwiche and Marquis' knowledge compilation map are considered. A number of families F of representations of objective functions over propositional variables, including linear pseudo-Boolean functions and more sophisticated ones, are considered. For each language L and each family F, the complexity of generating an optimal solution when the constraints are compiled into L and optimality is to be considered w.r.t. a function from F is identified.

Module templates for the specification of fault-tolerant systems

Critical systems are often too complex to be easily analyzed and validated as a whole. An interes... more

Comparing arguments using preference orderings for argument-based reasoning

Proceedings Eighth IEEE International Conference on Tools with Artificial Intelligence, 1996

Abstract Argument-based reasoning is a promising approach to handle inconsistent belief bases. Th... more

A Branching Heuristics for Quantified Renamable Horn Formulas

Lecture Notes in Computer Science, 2005

Many solvers have been designed for QBFs, the validity problem for Quantied Boolean Formulas for ... more Many solvers have been designed for QBFs, the validity problem for Quantied Boolean Formulas for the past few years. In this paper, we describe a new branching heuristics whose purpose is to pro- mote renamable Horn formulas. This heuristics is based on H ebrard&amp;amp;#x27;s algorithm for the recognition of such formulas. We present some experi- mental results obtained by our qbf solver Qb with the new branching heuristics and show how its performances are improved.

Fifty-Five Solvers in Vancouver: The SAT 2004 Competition

Lecture Notes in Computer Science, 2005

For the third consecutive year, a SAT competition was organized as a joint event with the SAT con... more For the third consecutive year, a SAT competition was organized as a joint event with the SAT conference. With 55 solvers from 25 author groups, the competition was a clear success. One of the noticeable facts from the 2004 competition is the superiority of incomplete solvers on satisfiable random k-SAT benchmarks. It can also be pointed out that the complete solvers awarded this year, namely Zchaff, jerusat1.3, satzoo-1.02, kncfsand march-eq, participated in the SAT 2003 competition (or at least former versions of those solvers). This paper is not reporting exhaustive competition results, already available in details online, but rather focuses on some remarkable results derived from the competition dataset.

Dependency management for the eclipse ecosystem

Proceedings of the 1st international workshop on Open component ecosystems - IWOCE '09, 2009

One of the strength of Eclipse, the well-known open platform for software development, is its ext... more One of the strength of Eclipse, the well-known open platform for software development, is its extensibility made possible by the built-in pluggability mechanisms. However those pluggability mechanisms only reveal their full potential when extensions created by others are made easy to distribute and obtain. The purpose of Eclipse p2 project is to build a platform addressing the challenges of distribution and obtention of Eclipse and its extensions, which poses the same dependency management issues than for component based systems. This paper focuses on the dependency management aspect of p2. It describes the metadata used to express dependencies, the overall functioning of our resolver and a description of our propositional constraints based encoding. To conclude we describe the challenges to address in future releases.

Automated metamorphic testing of variability analysis tools

by Emmanuel Lonca and Daniel Berre

Software Testing, Verification and Reliability, 2015

Variability determines the capability of software applications to be configured and customized. A... more Variability determines the capability of software applications to be configured and customized. A common need during the development of variability-intensive systems is the automated analysis of their underlying variability models, e.g. detecting contradictory configuration options. The analysis operations that are performed on variability models are often very complex, which hinders the testing of the corresponding analysis tools and makes difficult, often infeasible, to determine the correctness of their outputs, i.e. the well-known oracle problem in software testing. In this article, we present a generic approach for the automated detection of faults in variability analysis tools overcoming the oracle problem. Our work enables the generation of random variability models together with the exact set of valid configurations represented by these models. These test data are generated from scratch using step-wise transformations and assuring that certain constraints (a.k.a. metamorphic relations) hold at each step. To show the feasibility and generalizability of our approach, it has been used to automatically test several analysis tools in three variability domains: feature models, CUDF documents and Boolean formulas. Among other results, we detected 19 real bugs in 7 out of the 15 tools under test. 2 SEGURA ET AL. either at the problem or at the solution level. At the problem level, variability is managed in terms of features or requirements, using VMs such as feature models , orthogonal variability models or decision models . At the solution level, variability is modelled using domain-specific languages such as Kconfig in Linux , p2 in Eclipse or WS-Agreement in web services .

Using possibilistic logic for modeling qualitative decision: Answer Set Programming algorithms

International Journal of Approximate Reasoning, 2014

This paper describes a logical machinery for computing decisions, where the available knowledge o... more This paper describes a logical machinery for computing decisions, where the available knowledge on the state of the world is described by a possibilistic propositional logic base (i.e., a collection of logical statements associated with qualitative certainty levels), and where the preferences of the user are also described by another possibilistic logic base whose formula weights are interpreted in terms of priorities. Two attitudes are allowed for the decision maker: a pessimistic risk-averse one and an optimistic one. The computed decisions are in agreement with a qualitative counterpart to the classical theory of expected utility, recently developed by three of the authors. A link is established between this logical view of qualitative decision making and an ATMSbased computation procedure. E cient algorithms for computing pessimistic and optimistic optimal decisions are nally given in this logical setting (using some previous work of the fourth author).

Second QBF solvers evaluation

Qualitative Choice Logic

Kr, 2002

Qualitative choice logic (QCL) is a propositional logic for representing alternative, ranked opti... more Qualitative choice logic (QCL) is a propositional logic for representing alternative, ranked options for problem solutions. The logic adds to classical propositional logic a new connective called ordered disjunction: A × B intuitively means: if possible A, but if A is not possible then at least B. The semantics of qualitative choice logic is based on a preference relation among models. Consequences of QCL theories can be computed through a compilation to stratified knowledge bases which in turn can be compiled to classical propositional theories. We also discuss potential applications of the logic, several variants of QCL based on alternative inference relations, and their relation to existing nonmonotonic formalisms. 1

Comparing Arguments Using Preference Orderings for Argument-Based Reasoning

Proceedings of the 8th International Conference on Tools With Artificial Intelligence, Nov 16, 1996

Abstract Argument-based reasoning is a promising approach to handle inconsistent belief bases. Th... more

Logical Representation and Computation of Optimal Decisions in a Qualitative Setting

Aaai, 1998

This paper describes a logical machinery for computing decisions based on an ATMS procedure, wher... more This paper describes a logical machinery for computing decisions based on an ATMS procedure, where the available knowledge on the state of the world is described by a possibilistic propositional logic base (i.e., a collection of logical statements associated with qualitative certainty levels). The preferences of the user are also described by another possibilistic logic base whose formula weights are interpreted in terms of priorities and formulas express goals. Two attitudes are allowed for the decision maker: a pessimistic uncertainty-averse one and an optimistic one. The computed decisions are in agreement with a qualitative counterpart to classical expected utility theory for decision under uncertainty.

Complexity Results for Quantified Boolean Formulae Based on Complete Propositional Languages ∗ Sylvie Coste-Marquis

Several propositional fragments have been considered so far as target languages for knowledge com... more Several propositional fragments have been considered so far as target languages for knowledge compilation and used for improving computational tasks from major AI areas (like inference, diagnosis and planning); among them are the ordered binary decision diagrams, prime implicates, prime implicants, "formulae" in decomposable negation normal form. On the other hand, the validity problem val(QPROP P S ) for Quantified Boolean Formulae (QBF) has been acknowledged for the past few years as an important issue for AI, and many solvers have been designed. In this paper, the complexity of restrictions of the validity problem for QBF obtained by imposing the matrix of the input QBF to belong to propositional fragments used as target languages for compilation, is identified. It turns out that this problem remains hard (PSPACE-complete) even under severe restrictions on the matrix of the input. Nevertheless some tractable restrictions are pointed out.

$Figure 2. A formula in NNF pg. On the left part, the node marked *\ is decomposable while the node marked with the same symbol on the right part denotes a deterministic and smooth node.$

Using the Davis and Putnam Procedure for an Efficient Computation of Preferred Models

Ecai, 1996

Some famous problems (ATMS inference, ClosedWorld Reasoning (CWR) for instance) can be replaced b... more Some famous problems (ATMS inference, ClosedWorld Reasoning (CWR) for instance) can be replaced by aproblem of preferred model computation. We thus propose apreference relation between models based on a preference relationbetween literals and an &amp;amp;amp;amp;amp;amp;amp;amp;quot;efficient&amp;amp;amp;amp;amp;amp;amp;amp;quot; algorithm to computethe associated preferred models of a theory. Then, we applythis algorithm to ATMS inference and problems of CWR.Sub-problems like subsumption and label computation

An Alternative Inference for Qualitative Choice Logic

European Conference on Artificial Intelligence, 2006

The Sat4j library, release 2.2

Sat4j is a mature, open source library of SAT-based solvers in Java. It provides a modular SAT so... more Sat4j is a mature, open source library of SAT-based solvers in Java. It provides a modular SAT solver architecture designed to work with generic constraints. Such architecture is used to provide SAT, MaxSat and pseudo-boolean and solvers for lightweight constraint programming. Those solvers have been evaluated regularly in the corresponding international competitive events. The library has been adopted by several academic softwares and the widely used Eclipse platform, which relies on a pseudo-boolean solver from Sat4j for its plugins dependencies management since June 2008.

Challenges in the QBF Arena: the SAT’03 Evaluation of QBF Solvers

Lecture Notes in Computer Science, 2004

The implementation of effective reasoning tools for deciding the satisfiability of Quantified Boo... more The implementation of effective reasoning tools for deciding the satisfiability of Quantified Boolean Formulas (QBFs) is an important issue in several research fields such as Formal Verification, Planning, and Reasoning about Knowledge. Several QBF solvers have been implemented in the last few years, most of them extending the well-known Davis, Putnam, Logemann, Loveland procedure (DPLL) for propositional satisfiability (SAT). At the same time, a substantial breed of QBF benchmarks emerged, both in the form of statistical models for the generation of random formulas, and in the form of real-world instances. In this paper we report about the -first ever -evaluation of QBF solvers that was run as a joint event to SAT'03 Conference on Theory and Applications of Satisfiability Testing. Owing to the relative youngness of QBF tools and applications, we decided to run the comparison on a non-competitive basis, using the same technology that powered SAT'02 and SAT'03 competitions of SAT solvers. Running the evaluation enabled us to collect all sorts of data regarding the relative strength of different solvers and methods, the quality of the benchmarks, and to understand some of the current challenges for researchers involved in the QBF arena.

The Second QBF Solvers Comparative Evaluation

Lecture Notes in Computer Science, 2005

This paper reports about the 2004 comparative evaluation of solvers for quantified Boolean formul... more This paper reports about the 2004 comparative evaluation of solvers for quantified Boolean formulas (QBFs), the second in a series of non-competitive events established with the aim of assessing the advancements in the field of QBF reasoning and related research. We evaluated sixteen solvers on a test set of about one thousand benchmarks, selected from instances submitted to the evaluation and from those available at www.qbflib.org. In the paper we present the evaluation infrastructure, from the criteria used to select the benchmarks to the hardware set up, and we show different views about the results obtained, highlighting the strength of different solvers and the relative hardness of the benchmarks included in the test set.

The Essentials of the SAT 2003 Competition

Lecture Notes in Computer Science, 2004

The SAT 2003 Competition ran in February -May 2003, in conjunction with SAT'03 (the Sixth Fifth I... more The SAT 2003 Competition ran in February -May 2003, in conjunction with SAT'03 (the Sixth Fifth International Symposium on the Theory and Applications of Satisfiability Testing). One year after the SAT 2002 competition, it was not clear that significant progress could be made in the area in such a little time. The competition was a success -34 solvers and 993 benchmarks, needing 522 CPU days -with a number of brand new solvers. Several 2003 competitors were even able to solve within 15mn benchmarks remained unsolved within 6 hours by 2002 competitors. We report here the essential results of the competition, interpret and statistically analyse them, and at last provide some suggestions for the future competitions. sato (release 3.4) from Hantao Zhang . satzilla (release 0.9, v1 v2 v2-fixed) (v2s are hors concours) from Kevin Leyton-Brown, . Authors asked us to consider a new version of satzilla2. They discovered, during the contest, that satzilla2 had bugs in its learning phase, that led to wrong choices of solvers during the contest. The new version is refered as satzilla2-fixed. satzoo (release 0.98 v0 v1) from Niklas Een . tts (ternary tree solver, release 1.0, hors concours) from Ivor Spence. zchaff from Yinlei Yu and Lintao Zhang . zchaff was awarded best complete solver for both industrial and handmade categories at SAT'02 competition.

Aggregating Interval Orders by Propositional Optimization

Lecture Notes in Computer Science, 2009

Abstract. Aggregating preferences for findinga consensus between several agents is an important i... more Abstract. Aggregating preferences for findinga consensus between several agents is an important issue in many fields, like economics, decision theory and artificial intelligence. In this paper we focus on the problem of aggregating interval orders which are special preference structures allowing the introduction of tresholds for the indifference relation. We propose to solve this problem,by first translating it into a

On the Complexity of Optimization Problems based on Compiled NNF Representations

by Emmanuel Lonca and Daniel Berre

Optimization is a key task in a number of applications. When the set of feasible solutions under ... more Optimization is a key task in a number of applications. When the set of feasible solutions under consideration is of combinatorial nature and described in an implicit way as a set of constraints, optimization is typically NP-hard. Fortunately, in many problems, the set of feasible solutions does not often change and is independent from the user's request. In such cases, compiling the set of constraints describing the set of feasible solutions during an off-line phase makes sense, if this compilation step renders computationally easier the generation of a non-dominated, yet feasible solution matching the user's requirements and preferences (which are only known at the on-line step). In this article, we focus on propositional constraints. The subsets L of the NNF language analyzed in Darwiche and Marquis' knowledge compilation map are considered. A number of families F of representations of objective functions over propositional variables, including linear pseudo-Boolean functions and more sophisticated ones, are considered. For each language L and each family F, the complexity of generating an optimal solution when the constraints are compiled into L and optimality is to be considered w.r.t. a function from F is identified.

Module templates for the specification of fault-tolerant systems

Critical systems are often too complex to be easily analyzed and validated as a whole. An interes... more

Comparing arguments using preference orderings for argument-based reasoning

Proceedings Eighth IEEE International Conference on Tools with Artificial Intelligence, 1996

Abstract Argument-based reasoning is a promising approach to handle inconsistent belief bases. Th... more

A Branching Heuristics for Quantified Renamable Horn Formulas

Lecture Notes in Computer Science, 2005

Many solvers have been designed for QBFs, the validity problem for Quantied Boolean Formulas for ... more Many solvers have been designed for QBFs, the validity problem for Quantied Boolean Formulas for the past few years. In this paper, we describe a new branching heuristics whose purpose is to pro- mote renamable Horn formulas. This heuristics is based on H ebrard&amp;amp;#x27;s algorithm for the recognition of such formulas. We present some experi- mental results obtained by our qbf solver Qb with the new branching heuristics and show how its performances are improved.

Fifty-Five Solvers in Vancouver: The SAT 2004 Competition

Lecture Notes in Computer Science, 2005

For the third consecutive year, a SAT competition was organized as a joint event with the SAT con... more For the third consecutive year, a SAT competition was organized as a joint event with the SAT conference. With 55 solvers from 25 author groups, the competition was a clear success. One of the noticeable facts from the 2004 competition is the superiority of incomplete solvers on satisfiable random k-SAT benchmarks. It can also be pointed out that the complete solvers awarded this year, namely Zchaff, jerusat1.3, satzoo-1.02, kncfsand march-eq, participated in the SAT 2003 competition (or at least former versions of those solvers). This paper is not reporting exhaustive competition results, already available in details online, but rather focuses on some remarkable results derived from the competition dataset.

Dependency management for the eclipse ecosystem

Proceedings of the 1st international workshop on Open component ecosystems - IWOCE '09, 2009

One of the strength of Eclipse, the well-known open platform for software development, is its ext... more One of the strength of Eclipse, the well-known open platform for software development, is its extensibility made possible by the built-in pluggability mechanisms. However those pluggability mechanisms only reveal their full potential when extensions created by others are made easy to distribute and obtain. The purpose of Eclipse p2 project is to build a platform addressing the challenges of distribution and obtention of Eclipse and its extensions, which poses the same dependency management issues than for component based systems. This paper focuses on the dependency management aspect of p2. It describes the metadata used to express dependencies, the overall functioning of our resolver and a description of our propositional constraints based encoding. To conclude we describe the challenges to address in future releases.

Automated metamorphic testing of variability analysis tools

by Emmanuel Lonca and Daniel Berre

Software Testing, Verification and Reliability, 2015

Variability determines the capability of software applications to be configured and customized. A... more Variability determines the capability of software applications to be configured and customized. A common need during the development of variability-intensive systems is the automated analysis of their underlying variability models, e.g. detecting contradictory configuration options. The analysis operations that are performed on variability models are often very complex, which hinders the testing of the corresponding analysis tools and makes difficult, often infeasible, to determine the correctness of their outputs, i.e. the well-known oracle problem in software testing. In this article, we present a generic approach for the automated detection of faults in variability analysis tools overcoming the oracle problem. Our work enables the generation of random variability models together with the exact set of valid configurations represented by these models. These test data are generated from scratch using step-wise transformations and assuring that certain constraints (a.k.a. metamorphic relations) hold at each step. To show the feasibility and generalizability of our approach, it has been used to automatically test several analysis tools in three variability domains: feature models, CUDF documents and Boolean formulas. Among other results, we detected 19 real bugs in 7 out of the 15 tools under test. 2 SEGURA ET AL. either at the problem or at the solution level. At the problem level, variability is managed in terms of features or requirements, using VMs such as feature models , orthogonal variability models or decision models . At the solution level, variability is modelled using domain-specific languages such as Kconfig in Linux , p2 in Eclipse or WS-Agreement in web services .

Using possibilistic logic for modeling qualitative decision: Answer Set Programming algorithms

International Journal of Approximate Reasoning, 2014

This paper describes a logical machinery for computing decisions, where the available knowledge o... more This paper describes a logical machinery for computing decisions, where the available knowledge on the state of the world is described by a possibilistic propositional logic base (i.e., a collection of logical statements associated with qualitative certainty levels), and where the preferences of the user are also described by another possibilistic logic base whose formula weights are interpreted in terms of priorities. Two attitudes are allowed for the decision maker: a pessimistic risk-averse one and an optimistic one. The computed decisions are in agreement with a qualitative counterpart to the classical theory of expected utility, recently developed by three of the authors. A link is established between this logical view of qualitative decision making and an ATMSbased computation procedure. E cient algorithms for computing pessimistic and optimistic optimal decisions are nally given in this logical setting (using some previous work of the fourth author).

Second QBF solvers evaluation