The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Roberto Sebastiani - One of the best experts on this subject based on the ideXlab platform.
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to ackermann ize or not to ackermann ize on efficiently handling uninterpreted function symbols in smt t
International Conference on Logic Programming, 2006Co-Authors: Roberto Bruttomesso, Alessandro Cimatti, Anders Franzen, Alberto Griggio, Alessandro Santuari, Roberto SebastianiAbstract:Satisfiability Modulo Theories is the problem of deciding the satisfiability of a formula with respect to a given Background Theory . When is the combination of two simpler theories and , a standard and general approach is to handle the integration of and by performing some form of search on the equalities between the shared variables. A frequent and very relevant sub-case of is when is the Theory of Equality and Uninterpreted Functions . For this case, an alternative approach is to eliminate first all uninterpreted function symbols by means of Ackermann's expansion, and then to solve the resulting problem. In this paper we build on the empirical observation that there is no absolute winner between these two alternative approaches, and that the performance gaps between them are often dramatic, in either direction. We propose a simple technique for estimating a priori the costs and benefits, in terms of the size of the search space of an tool, of applying Ackermann's expansion to all or part of the function symbols. A thorough experimental analysis, including the benchmarks of the SMT'05 competition, shows that the proposed technique is extremely effective in improving the overall performance of the tool.
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to ackermann ize or not to ackermann ize on efficiently handling uninterpreted function symbols in smt euf t
Lecture Notes in Computer Science, 2006Co-Authors: Roberto Bruttomesso, Alessandro Cimatti, Anders Franzen, Alberto Griggio, Alessandro Santuari, Roberto SebastianiAbstract:Satisfiability Modulo Theories (SMT(T)) is the problem of deciding the satisfiability of a formula with respect to a given Background Theory T. When T is the combination of two simpler theories T 1 and T 2 . (SMT(T 1 ∪ T 2 )), a standard and general approach is to handle the integration of T 1 and T 2 by performing some form of search on the equalities between the shared variables. A frequent and very relevant sub-case of SMT(T 1 ∪ T 2 ) is when T 1 is the Theory of Equality and Uninterpreted Functions (EUF). For this case, an alternative approach is to eliminate first all uninterpreted function symbols by means of Ackermann's expansion, and then to solve the resulting SMT (T 2 ) problem. In this paper we build on the empirical observation that there is no absolute winner between these two alternative approaches, and that the performance gaps between them are often dramatic, in either direction. We propose a simple technique for estimating a priori the costs and benefits, in terms of the size of the search space of an SMT tool, of applying Ackermann's expansion to all or part of the function symbols. A thorough experimental analysis, including the benchmarks of the SMT'05 competition, shows that the proposed technique is extremely effective in improving the overall performance of the SMT tool.
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efficient satisfiability modulo theories via delayed Theory combination
Computer Aided Verification, 2005Co-Authors: Marco Bozzano, Roberto Bruttomesso, Alessandro Cimatti, Tommi Junttila, Silvio Ranise, Peter Van Rossum, Roberto SebastianiAbstract:The problem of deciding the satisfiability of a quantifier-free formula with respect to a Background Theory, also known as Satisfiability Modulo Theories (SMT), is gaining increasing relevance in verification: representation capabilities beyond propositional logic allow for a natural modeling of real-world problems (e.g., pipeline and RTL circuits verification, proof obligations in software systems). In this paper, we focus on the case where the Background Theory is the combination T1∪T2 of two simpler theories. Many SMT procedures combine a boolean model enumeration with a decision procedure for T1∪T2, where conjunctions of literals can be decided by an integration schema such as Nelson-Oppen, via a structured exchange of interface formulae (e.g., equalities in the case of convex theories, disjunctions of equalities otherwise). We propose a new approach for SMT(T1∪T2), called Delayed Theory Combination, which does not require a decision procedure for T1∪T2, but only individual decision procedures for T1 and T2, which are directly integrated into the boolean model enumerator. This approach is much simpler and natural, allows each of the solvers to be implemented and optimized without taking into account the others, and it nicely encompasses the case of non-convex theories. We show the effectiveness of the approach by a thorough experimental comparison.
Roberto Bruttomesso - One of the best experts on this subject based on the ideXlab platform.
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to ackermann ize or not to ackermann ize on efficiently handling uninterpreted function symbols in smt t
International Conference on Logic Programming, 2006Co-Authors: Roberto Bruttomesso, Alessandro Cimatti, Anders Franzen, Alberto Griggio, Alessandro Santuari, Roberto SebastianiAbstract:Satisfiability Modulo Theories is the problem of deciding the satisfiability of a formula with respect to a given Background Theory . When is the combination of two simpler theories and , a standard and general approach is to handle the integration of and by performing some form of search on the equalities between the shared variables. A frequent and very relevant sub-case of is when is the Theory of Equality and Uninterpreted Functions . For this case, an alternative approach is to eliminate first all uninterpreted function symbols by means of Ackermann's expansion, and then to solve the resulting problem. In this paper we build on the empirical observation that there is no absolute winner between these two alternative approaches, and that the performance gaps between them are often dramatic, in either direction. We propose a simple technique for estimating a priori the costs and benefits, in terms of the size of the search space of an tool, of applying Ackermann's expansion to all or part of the function symbols. A thorough experimental analysis, including the benchmarks of the SMT'05 competition, shows that the proposed technique is extremely effective in improving the overall performance of the tool.
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to ackermann ize or not to ackermann ize on efficiently handling uninterpreted function symbols in smt euf t
Lecture Notes in Computer Science, 2006Co-Authors: Roberto Bruttomesso, Alessandro Cimatti, Anders Franzen, Alberto Griggio, Alessandro Santuari, Roberto SebastianiAbstract:Satisfiability Modulo Theories (SMT(T)) is the problem of deciding the satisfiability of a formula with respect to a given Background Theory T. When T is the combination of two simpler theories T 1 and T 2 . (SMT(T 1 ∪ T 2 )), a standard and general approach is to handle the integration of T 1 and T 2 by performing some form of search on the equalities between the shared variables. A frequent and very relevant sub-case of SMT(T 1 ∪ T 2 ) is when T 1 is the Theory of Equality and Uninterpreted Functions (EUF). For this case, an alternative approach is to eliminate first all uninterpreted function symbols by means of Ackermann's expansion, and then to solve the resulting SMT (T 2 ) problem. In this paper we build on the empirical observation that there is no absolute winner between these two alternative approaches, and that the performance gaps between them are often dramatic, in either direction. We propose a simple technique for estimating a priori the costs and benefits, in terms of the size of the search space of an SMT tool, of applying Ackermann's expansion to all or part of the function symbols. A thorough experimental analysis, including the benchmarks of the SMT'05 competition, shows that the proposed technique is extremely effective in improving the overall performance of the SMT tool.
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efficient satisfiability modulo theories via delayed Theory combination
Computer Aided Verification, 2005Co-Authors: Marco Bozzano, Roberto Bruttomesso, Alessandro Cimatti, Tommi Junttila, Silvio Ranise, Peter Van Rossum, Roberto SebastianiAbstract:The problem of deciding the satisfiability of a quantifier-free formula with respect to a Background Theory, also known as Satisfiability Modulo Theories (SMT), is gaining increasing relevance in verification: representation capabilities beyond propositional logic allow for a natural modeling of real-world problems (e.g., pipeline and RTL circuits verification, proof obligations in software systems). In this paper, we focus on the case where the Background Theory is the combination T1∪T2 of two simpler theories. Many SMT procedures combine a boolean model enumeration with a decision procedure for T1∪T2, where conjunctions of literals can be decided by an integration schema such as Nelson-Oppen, via a structured exchange of interface formulae (e.g., equalities in the case of convex theories, disjunctions of equalities otherwise). We propose a new approach for SMT(T1∪T2), called Delayed Theory Combination, which does not require a decision procedure for T1∪T2, but only individual decision procedures for T1 and T2, which are directly integrated into the boolean model enumerator. This approach is much simpler and natural, allows each of the solvers to be implemented and optimized without taking into account the others, and it nicely encompasses the case of non-convex theories. We show the effectiveness of the approach by a thorough experimental comparison.
Alessandro Cimatti - One of the best experts on this subject based on the ideXlab platform.
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to ackermann ize or not to ackermann ize on efficiently handling uninterpreted function symbols in smt t
International Conference on Logic Programming, 2006Co-Authors: Roberto Bruttomesso, Alessandro Cimatti, Anders Franzen, Alberto Griggio, Alessandro Santuari, Roberto SebastianiAbstract:Satisfiability Modulo Theories is the problem of deciding the satisfiability of a formula with respect to a given Background Theory . When is the combination of two simpler theories and , a standard and general approach is to handle the integration of and by performing some form of search on the equalities between the shared variables. A frequent and very relevant sub-case of is when is the Theory of Equality and Uninterpreted Functions . For this case, an alternative approach is to eliminate first all uninterpreted function symbols by means of Ackermann's expansion, and then to solve the resulting problem. In this paper we build on the empirical observation that there is no absolute winner between these two alternative approaches, and that the performance gaps between them are often dramatic, in either direction. We propose a simple technique for estimating a priori the costs and benefits, in terms of the size of the search space of an tool, of applying Ackermann's expansion to all or part of the function symbols. A thorough experimental analysis, including the benchmarks of the SMT'05 competition, shows that the proposed technique is extremely effective in improving the overall performance of the tool.
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to ackermann ize or not to ackermann ize on efficiently handling uninterpreted function symbols in smt euf t
Lecture Notes in Computer Science, 2006Co-Authors: Roberto Bruttomesso, Alessandro Cimatti, Anders Franzen, Alberto Griggio, Alessandro Santuari, Roberto SebastianiAbstract:Satisfiability Modulo Theories (SMT(T)) is the problem of deciding the satisfiability of a formula with respect to a given Background Theory T. When T is the combination of two simpler theories T 1 and T 2 . (SMT(T 1 ∪ T 2 )), a standard and general approach is to handle the integration of T 1 and T 2 by performing some form of search on the equalities between the shared variables. A frequent and very relevant sub-case of SMT(T 1 ∪ T 2 ) is when T 1 is the Theory of Equality and Uninterpreted Functions (EUF). For this case, an alternative approach is to eliminate first all uninterpreted function symbols by means of Ackermann's expansion, and then to solve the resulting SMT (T 2 ) problem. In this paper we build on the empirical observation that there is no absolute winner between these two alternative approaches, and that the performance gaps between them are often dramatic, in either direction. We propose a simple technique for estimating a priori the costs and benefits, in terms of the size of the search space of an SMT tool, of applying Ackermann's expansion to all or part of the function symbols. A thorough experimental analysis, including the benchmarks of the SMT'05 competition, shows that the proposed technique is extremely effective in improving the overall performance of the SMT tool.
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efficient satisfiability modulo theories via delayed Theory combination
Computer Aided Verification, 2005Co-Authors: Marco Bozzano, Roberto Bruttomesso, Alessandro Cimatti, Tommi Junttila, Silvio Ranise, Peter Van Rossum, Roberto SebastianiAbstract:The problem of deciding the satisfiability of a quantifier-free formula with respect to a Background Theory, also known as Satisfiability Modulo Theories (SMT), is gaining increasing relevance in verification: representation capabilities beyond propositional logic allow for a natural modeling of real-world problems (e.g., pipeline and RTL circuits verification, proof obligations in software systems). In this paper, we focus on the case where the Background Theory is the combination T1∪T2 of two simpler theories. Many SMT procedures combine a boolean model enumeration with a decision procedure for T1∪T2, where conjunctions of literals can be decided by an integration schema such as Nelson-Oppen, via a structured exchange of interface formulae (e.g., equalities in the case of convex theories, disjunctions of equalities otherwise). We propose a new approach for SMT(T1∪T2), called Delayed Theory Combination, which does not require a decision procedure for T1∪T2, but only individual decision procedures for T1 and T2, which are directly integrated into the boolean model enumerator. This approach is much simpler and natural, allows each of the solvers to be implemented and optimized without taking into account the others, and it nicely encompasses the case of non-convex theories. We show the effectiveness of the approach by a thorough experimental comparison.
Muhammad E Abdelhamid - One of the best experts on this subject based on the ideXlab platform.
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storing energy in plastics a review on conducting polymers their role in electrochemical energy storage
RSC Advances, 2015Co-Authors: Muhammad E Abdelhamid, Anthony P Omullane, Graeme A SnookAbstract:Conducting polymers have become the focus of research due to their interesting properties, such as a wide range of conductivity, facile production, mechanical stability, light weight and low cost and the ease with which conducting polymers can be nanostructured to meet the specific application. They have become valuable materials for many applications, such as energy storage and generation. Recently, conducting polymers have been studied for use in supercapacitors, batteries and fuel cells. This article is to briefly discuss the Background & Theory behind their conductivity as well as to highlight the recent contributions of conducting polymers to the field of energy. Furthermore, the methods of production of the conducting polymers in addition to the different ways utilised to nano-engineer special morphologies are discussed.
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storing energy in plastics a review on conducting polymers their role in electrochemical energy storage
Science & Engineering Faculty, 2015Co-Authors: Muhammad E Abdelhamid, Anthony P Omullane, Graeme A SnookAbstract:Conducting polymers have become the focus of research due to their interesting properties, such as a wide range of conductivity, facile production, mechanical stability, light weight and low cost and due to the ease with which conducting polymers can be nanostructured to meet the specific application. They have become valuable materials for many applications, such as energy storage and generation. Recently, conducting polymers have been studied to be used in supercapacitors, battery electrode and fuel cells. This article is to briefly discuss the Background & Theory behind their conductivity as well as to highlight the recent contributions of conducting polymers to the field of energy and their significance. Furthermore, the methods of production of the conducting polymers in addition to the different ways utilised to nano-engineer special morphologies are discussed.
Nick S Jones - One of the best experts on this subject based on the ideXlab platform.
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generalized methods and solvers for noise removal from piecewise constant signals i Background Theory
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2011Co-Authors: Max A Little, Nick S JonesAbstract:Removing noise from piecewise constant (PWC) signals is a challenging signal processing problem arising in many practical contexts. For example, in exploration geosciences, noisy drill hole records need to be separated into stratigraphic zones, and in biophysics, jumps between molecular dwell states have to be extracted from noisy fluorescence microscopy signals. Many PWC denoising methods exist, including total variation regularization, mean shift clustering, stepwise jump placement, running medians, convex clustering shrinkage and bilateral filtering; conventional linear signal processing methods are fundamentally unsuited. This paper (part I, the first of two) shows that most of these methods are associated with a special case of a generalized functional, minimized to achieve PWC denoising. The minimizer can be obtained by diverse solver algorithms, including stepwise jump placement, convex programming, finite differences, iterated running medians, least angle regression, regularization path following and coordinate descent. In the second paper, part II, we introduce novel PWC denoising methods, and comparisons between these methods performed on synthetic and real signals, showing that the new understanding of the problem gained in part I leads to new methods that have a useful role to play.
