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Reasoning support for risk prediction and prevention in independent living

theory and practice of logic programming 2011年第2-3期11卷 361-395页

作者： Mileo, A. Merico, D. Bisiani, R. Univ Milano Bicocca NOMADIS Res Lab Dept Informat Syst & Commun I-20126 Milan Italy

In recent years there has been a growing interest in solutions for the delivery of clinical care for the elderly because of the large increase in aging population. Monitoring a patient in his home environment is necessary to ensure continuity of care in home settings, but, to be useful, this activity must not be too invasive for patients and a burden for caregivers. We prototyped a system called Secure and IN Dependent lIving (SINDI), focused on (a) collecting a limited amount of data about the person and the environment through Wireless Sensor Networks (WSN), and (b) inferring from these data enough information to support caregivers in understanding patients' well-being and in predicting possible evolutions of their health. Our hierarchical logic-based model of health combines data from different sources, sensor data, tests results, common-sense knowledge and patient's clinical profile at the lower level, and correlation rules between health conditions across upper levels. The logical formalization and the reasoning process are based on Answer Set programming. The expressive power of this logic programming paradigm makes it possible to reason about health evolution even when the available information is incomplete and potentially incoherent, while declarativity simplifies rules specification by caregivers and allows automatic encoding of knowledge. This paper describes how these issues have been targeted in the application scenario of the SINDI system.

关键词： answer set programming wireless sensor networks independent living prediction context-awareness knowledge representation dependency graph

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On the implementation of the probabilistic logic programming language ProbLog

On the implementation of the probabilistic logic programming...

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24th International Conference on logic programming (ICLP)

作者： Kimmig, Angelika Demoen, Bart De Raedt, Luc Costa, Vitor Santos Rocha, Ricardo Katholieke Univ Leuven Dept Comp Wetenschappen B-3001 Heverlee Belgium Univ Porto Fac Sci CRACS P-4169007 Oporto Portugal Univ Porto Fac Sci INESC Porto LA P-4169007 Oporto Portugal

The past few years have seen a surge of interest in the field of probabilistic logic learning and statistical relational learning. In this endeavor, many probabilistic logics have been developed. ProbLog is a recent probabilistic extension of Prolog motivated by the mining of large biological networks. In ProbLog, facts can be labeled with probabilities. These facts are treated as mutually independent random variables that indicate whether these facts belong to a randomly sampled program. Different kinds of queries can be posed to ProbLog programs. We introduce algorithms that allow the efficient execution of these queries, discuss their implementation on top of the YAP-Prolog system, and evaluate their performance in the context of large networks of biological entities.

关键词： Probabilistic logic programming Exact and approximative inference Implementation

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On elementary loops of logic programs

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theory and practice of logic programming 2011年第6期11卷 953-988页

作者： Gebser, Martin Lee, Joohyung Lierler, Yuliya Univ Potsdam Inst Informat Potsdam Germany Arizona State Univ Sch Comp Informat & Decis Syst Engn Tempe AZ USA Univ Kentucky Dept Comp Sci Lexington KY 40506 USA

Using the notion of an elementary loop, Gebser and Schaub (2005. Proceedings of the Eighth International Conference on logic programming and Nonmonotonic Reasoning (LPNMR'05), 53-65) refined the theorem on loop formulas attributable to Lin and Zhao (2004) by considering loop formulas of elementary loops only. In this paper, we reformulate the definition of an elementary loop, extend it to disjunctive programs, and study several properties of elementary loops, including how maximal elementary loops are related to minimal unfounded sets. The results provide useful insights into the stable model semantics in terms of elementary loops. For a nondisjunctive program, using a graph-theoretic characterization of an elementary loop, we show that the problem of recognizing an elementary loop is tractable. On the other hand, we also show that the corresponding problem is coNP-complete for a disjunctive program. Based on the notion of an elementary loop, we present the class of Head-Elementary-loop-Free (HEF) programs, which strictly generalizes the class of Head-Cycle-Free (HCF) programs attributable to Ben-Eliyahu and Dechter (1994. Annals of Mathematics and Artificial Intelligence 12, 53-87). Like an Ha: program, an HEF program can be turned into an equivalent nondisjunctive program in polynomial time by shifting head atoms into the body.

关键词： stable model semantics loop formulas unfounded sets

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Efficient instance retrieval of subgoals for subsumptive tabled evaluation of logic programs

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theory and practice of logic programming 2011年第4-5期11卷 697-712页

作者： Cruz, Flavio Rocha, Ricardo Univ Porto Fac Sci CRACS P-4169007 Oporto Portugal Univ Porto Fac Sci INESC Porto LA P-4169007 Oporto Portugal

Tabled evaluation is an implementation technique that solves some problems of traditional Prolog systems in dealing with recursion and redundant computations. Most tabling engines determine if a tabled subgoal will produce or consume answers by using variant checks. A more refined method, named call subsumption, considers that a subgoal A will consume from a subgoal B if A is subsumed by (an instance of) B, thus allowing greater answer reuse. We recently developed an extension, called Retroactive Call Subsumption, that improves upon call subsumption by supporting bidirectional sharing of answers between subsumed/subsuming subgoals. In this paper, we present both an algorithm and an extension to the table space data structures to efficiently implement instance retrieval of subgoals for subsumptive tabled evaluation of logic programs. Experiments results using the YapTab tabling system show that our implementation performs quite well on some complex benchmarks and is robust enough to handle a large number of subgoals without performance degradation.

关键词： tabled evaluation call subsumption implementation

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Efficient local unfolding with ancestor stacks

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theory and practice of logic programming 2011年第1期11卷 1-32页

作者： Puebla, German Albert, Elvira Hermenegildo, Manuel Tech Univ Madrid Sch Comp Sci E-28660 Madrid Spain Univ Complutense Madrid Sch Comp Sci E-28040 Madrid Spain

The most successful unfolding rules used nowadays in the partial evaluation of logic programs are based on well quasi orders (wqo) applied over (covering) ancestors, i.e., a subsequence of the atoms selected during a derivation. Ancestor (sub)sequences are used to increase the specialization power of unfolding while still guaranteeing termination and also to reduce the number of atoms for which the wqo has to be checked. Unfortunately, maintaining the structure of the ancestor relation during unfolding introduces significant overhead. We propose an efficient, practical local unfolding rule based on the notion of covering ancestors which can be used in combination with a wqo and allows a stack-based implementation without losing any opportunities for specialization. Using our technique, certain nonleftmost unfoldings are allowed as long as local unfolding is performed, i.e., we cover depth-first strategies. To deal with practical programs, we propose assertion-based techniques which allow our approach to treat programs that include (Prolog) built-ins and external predicates in a very extensible manner, for the case of leftmost unfolding. Finally, we report on our implementation of these techniques embedded in a practical partial evaluator, which shows that our techniques, in addition to dealing with practical programs, are also significantly more efficient in time and somewhat more efficient in memory than traditional tree-based implementations.

关键词： partial evaluation partial deduction logic programming prolog SLD semantics local unfolding

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Fuzzy Portfolio Selection Problem with Different Borrowing and Lending Rates

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MATHEMATICAL PROBLEMS IN ENGINEERING 2011年第1期2011卷 1-15页

作者： Chen, Wei Yang, Yiping Ma, Hui Capital Univ Econ & Business Sch Informat Beijing 100070 Peoples R China

As we know, borrowing and lending risk-free assets arise extensively in the theory and practice of finance. However, little study has ever investigated them in fuzzy portfolio problem. In this paper, the returns of each assets are assumed to be fuzzy variables, then following the mean-variance approach, a new possibilistic portfolio selection model with different interest rates for borrowing and lending is proposed, in which the possibilistic semiabsolute deviation of the return is used to measure investment risk. The conventional probabilistic mean variance model can be transformed to a linear programming problem under possibility distributions. Finally, a numerical example is given to illustrate the modeling idea and the impact of borrowing and lending on optimal decision making.

关键词： FUZZY logic LINEAR programming OPTIMAL designs (Statistics) MATHEMATICAL models of decision making MATHEMATICAL models of interest rates

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Reasoning support for risk prediction and prevention in independent living

Reasoning support for risk prediction and prevention in inde...

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24th International Conference on logic programming (ICLP)

作者： Mileo, A. Merico, D. Bisiani, R. Univ Milano Bicocca NOMADIS Res Lab Dept Informat Syst & Commun I-20126 Milan Italy

关键词： answer set programming wireless sensor networks independent living prediction context-awareness knowledge representation dependency graph

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A general framework for equivalences in Answer-Set programming by countermodels in the logic of Here-and-There

A general framework for equivalences in Answer-Set Programmi...

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24th International Conference on logic programming (ICLP)

作者： Fink, Michael Vienna Univ Technol Inst Informat Syst A-1040 Vienna Austria

Different notions of equivalence, such as the prominent notions of strong and uniform equivalence, have been studied in Answer-Set programming, mainly for the purpose of identifying programs that can serve as substitutes without altering the semantics, for instance in program optimization. Such semantic comparisons are usually characterized by various selections of models in the logic of Here-and- There (HT). For uniform equivalence however, correct characterizations in terms of HT-models can only be obtained for finite theories, respectively programs. In this paper, we show that a selection of countermodels in HT captures uniform equivalence also for infinite theories. This result is turned into coherent characterizations of the different notions of equivalence by countermodels, as well as by a mixture of HT-models and countermodels (so-called equivalence interpretations). Moreover, we generalize the so-called notion of relativized hyperequivalence for programs to propositional theories, and apply the same methodology in order to obtain a semantic characterization which is amenable to infinite settings. This allows for a lifting of the results to first-order theories under a very general semantics given in terms of a quantified version of HT. We thus obtain a general framework for the study of various notions of equivalence for theories under answer-set semantics. Moreover, we prove an expedient property that allows for a simplified treatment of extended signatures, and provide further results for non-ground logic programs. In particular, uniform equivalence coincides under open and ordinary answer-set semantics, and for finite non-ground programs under these semantics, also the usual characterization of uniform equivalence in terms of maximal and total HT-models of the grounding is correct, even for infinite domains, when corresponding ground programs are infinite.

关键词： Answer-Set programming Uniform equivalence Relativized equivalence Knowledge representation

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Automatic music composition using answer set programming

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theory and practice of logic programming 2011年第2-3期11卷 397-427页

作者： Boenn, Georg Brain, Martin De Vos, Marina Ffitch, John Univ Glamorgan Cardiff Sch Creat & Cultural Ind Pontypridd CF37 1DL M Glam Wales Univ Bath Dept Comp Sci Bath BA2 7AY Avon England

Music composition used to be a pen and paper activity. These days music is often composed with the aid of computer software, even to the point where the computer composes parts of the score autonomously. The composition of most styles of music is governed by rules. We show that by approaching the automation, analysis and verification of composition as a knowledge representation task and formalising these rules in a suitable logical language, powerful and expressive intelligent composition tools can be easily built. This application paper describes the use of answer set programming to construct an automated system, named Anton, that can compose melodic, harmonic and rhythmic music, diagnose errors in human compositions and serve as a computer-aided composition tool. The combination of harmonic, rhythmic and melodic composition in a single framework makes Anton unique in the growing area of algorithmic composition. With near real-time composition, Anton reaches the point where it can not only be used as a component in an interactive composition tool but also has the potential for live performances and concerts or automatically generated background music in a variety of applications. With the use of a fully declarative language and an "off-the-shelf" reasoning engine, Anton provides the human composer a tool which is significantly simpler, more compact and more versatile than other existing systems.

关键词： Answer set programming Applications of ASP Music composition Algorithmic composition Harmonic and melodic composition Diagnosis

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Granularity and Concurrent Separation logic

Granularity and Concurrent Separation Logic

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22nd Conference on Concurrency theory (CONCUR 2011)

作者： Hayman, Jonathan Univ Cambridge Comp Lab Cambridge CB2 1TN England

ISBN: (纸本)9783642232169;9783642232176

When defining the semantics of shared-memory concurrent programming languages, one conventionally has to make assumptions about the atomicity of actions such as assignments. Running on physical hardware, these assumptions can fail to hold in practice, which puts in question reasoning about their concurrent execution. We address an observation, due to John Reynolds, that processes proved sound in concurrent separation logic are separated to an extent that these assumptions can be disregarded, so judgements remain sound even if the assumptions on atomicity fail to hold. We make use of a Petri-net based semantics for concurrent separation logic with explicit representations of the key notions of ownership and interference. A new characterization of the separation of processes is given and is shown to be stronger than existing race-freedom results for the logic. Exploiting this, sufficient criteria are then established for an operation of refinement of processes capable of changing the atomicity of assignments.

关键词： Semantics

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