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6th international conference on principles and practice of programming in Java, PPPJ 2008

ISBN: (纸本)9781605582238

the proceedings contain 19 papers. the topics discussed include: the JavaFest: a collaborative learning technique for Java programming courses;an experimental environment for teaching Java security;patterns and traceability in teaching software architecture;a framework for command processing in Java/Swing programs based on the MVC pattern;the PIM: an innovative robot coordination model based on Java thread migration;self-configuring object-to-relational mapping queries;portable execution of legacy binaries on the Java virtual machine;a lazy developer approach: building a JVM with third party software;speculative improvements to verifiable bounds check elimination;constraint based optimization of stationary fields;optimized strings for Java HotSpot™ virtual machine;and SlimVM: optimistic partial program loading for connected embedded Java virtual machines.

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A constraint programming Approach for Allocation and Scheduling on the CELL Broadband Engine

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14th international conference on principles and practice of constraint programming (CP 2008)

作者： Benini, Luca Lombardi, Michele Milano, Michela Ruggiero, Martino Univ Bologna DEIS I-40136 Bologna Italy

ISBN: (纸本)9783540859574

the Cell BE processor provides both scalable computation power and flexibility, and it is already being adopted for many computational intensive applications like aerospace, defense, medical imaging and gaming. Despite of its merits, it also presents many challenges. as it is now widely known that is very difficult to program the Cell BE in an efficient manner. Hence, the creation of an efficient software development framework is becoming the key challenge for this computational platform. We have developed a novel software toolkit, called Cellflow, which enables developers to quickly build multi-task applications for Cell-based platform. We support programmers from the initial stage of their work, through a development-time software infrastructure, to the final stage of the application development, proposing a safe and easy-to-use explicit parallel programming model. A fundamental component of the software toolkit is the off-line allocator and scheduler that manages hardware resources while optimizing performance metrics such as execution time, allocation costs, power. the optimization engine receives as input a task graph representing an application, the hardware resources and produces an optimal allocation and scheduling. We have developed various approaches, either based on decomposition [5] or based on pure constraint programming, this latter being the core of this paper. We have identified instance features that guide toward the choice of the best solver for the instance at hand. Experimental result show that constraint programming (possibly combined with Integer programming) is a proper tool for dealing with this kind of applications achieving very good performance.

关键词： constraint programming

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Search Strategies for Rectangle Packing

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14th international conference on principles and practice of constraint programming (CP 2008)

作者： Simonis, Helmut O'Sullivan, Barry Natl Univ Ireland Univ Coll Cork Dept Comp Sci Cork Constraint Computat Ctr Cork Ireland

ISBN: (纸本)9783540859574

Rectangle (square) packing problems involve packing all squares with sires 1 x 1 to n x n into the minimum area enclosing rectangle (respectively, square). Rectangle packing is a variant of an important problem in a variety of real-world settings. For example, in electronic design automation, the packing of blocks into it circuit layout is essentially a rectangle packing problem. Rectangle packing problems are also motivated by applications in scheduling. In this paper we demonstrate thin an "off-the-shelf" constraint programming system. SICStus Prolog. outperforms recently developed ad-hoc approaches by over three orders of magnitude. We adopt the standard CP model for these problems, and study a variety of search strategies and improvements to solve large rectangle packing problems. As well as being over three orders of magnitude faster than the current state-of-the-art, we close eight open problems: two rectangle packing problems and six square packing problems. Our approach has other advantages over the state-of-the-art, Such its being trivially modifiable to exploit multi-core computing platforms to parallelise search, although we use only a single-core in our experiments. We argue that rectangle packing is a domain where constraint pro-ramming significantly outperforms hand-crafted ad-hoc systems developed for this problem. this provides the CP community with a convincing success story.

关键词： Geometry

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MAX ONES generalized to larger domains

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SIAM JOURNAL ON COMPUTING 2008年第1期38卷 329-365页

作者： Jonsson, Peter Kuivinen, Fredrik Nordh, Gustav Linkoping Univ Dept Comp & Informat Sci SE-58183 Linkoping Sweden Ecole Polytech LIX F-91128 Palaiseau France

We study a family of problems, called Maximum Solution, where the objective is to maximize a linear goal function over the feasible integer assignments to a set of variables subject to a set of constraints. When the domain is Boolean (i.e., restricted to {0, 1}), the maximum solution problem is identical to the well-studied MAX ONES problem, and the approximability is completely understood for all restrictions on the underlying constraints [S. Khanna, M. Sudan, L. Trevisan, and D. P. Williamson, SIAM J. Comput., 30 (2001), pp. 1863-1920]. We continue this line of research by considering domains containing more than two elements. We present two main results: a complete classification for the approximability of all maximal constraint languages over domains of cardinality at most 4, and a complete classification of the approximability of the problem when the set of allowed constraints contains all permutation constraints. Under the assumption that a conjecture due to Szczepara [Minimal Clones Generated by Groupoids, Ph. D. thesis, Universite de Montreal, Montreal, QC, 1996] holds, we give a complete classification for all maximal constraint languages. these classes of languages are well studied in universal algebra and computer science;they have, for instance, been considered in connection with machine learning and constraint satisfaction. Our results are proved by using algebraic results from clone theory, and the results indicate that this approach is very powerful for classifying the approximability of certain optimization problems.

关键词： combinatorial optimization constraint satisfaction approximability universal algebra

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Relaxations for Compiled Over-Constrained Problems

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14th international conference on principles and practice of constraint programming (CP 2008)

作者： PaPadopoulos, Alexandre O'Sullivan, Barry Univ Collegc Cork Dept Comp Sci Cork Constraint Computat Ctr Cork Ireland

ISBN: (纸本)9783540859574

In many real-world settings, e.g. product configuration, constraint satisfaction problems are compiled into automata or binary decision diagrams, which can be seen as instances of Darwiche's negation normal form. In this paper we consider settings in which a foreground set of constraints can he added to a set of consistent background constraints, that are compactly represented in a compiled form. When the set of foreground constraints introduces inconsistencies with the background constraints we wish to find relaxations of the problem by identifying the subset of the foreground constraints that do not introduce inconsistency;such a subset is called a relaxation. this paper is organised in two parts. First, two novel algorithms for finding relaxations based on automata arc presented. they find the relaxation that is consistent with the largest (or smallest) number of solutions from amongst the longest ones (first algorithm), or from amongst the set-wise maximal ones (second algorithm). then, we generalise our results by identifying the properties that the target compilation language must have for our approach to apply. Finally, we show empirically that on average our algorithms can be more than 500 times faster than a current state-of-the-art algorithm.

关键词： Binary decision diagrams

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Guarded hybrid knowledge bases

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thEORY AND practice OF LOGIC programming 2008年第3期8卷 411-429页

作者： Heymans, Stijn De Bruijn, Jos Predoiu, Livia Feier, Cristina Van Niewenborgh, Davy Univ Innsbruck Digital Enterprise Res Inst A-6020 Innsbruck Austria Free Univ Bozen Bolzano Fac Comp Sci I-39100 Bozen Bolzano Italy Univ Mannheim Inst Comp Sci D-68159 Mannheim Germany Vrije Univ Brussel VUB Dept Comp Sci B-1050 Brussels Belgium

Recently, there has been a lot of interest in the integration of Description Logics (DL) and rules on the Semantic Web. We define guarded hybrid knowledge bases (or g-hybrid knowledge bases) as knowledge bases that consist of a Description Logic knowledge base and a guarded logic program, similar to the DL+log knowledge bases from Rosati (In Proceedings of the 10th international conference on principles of Knowledge Representation and Reasoning, AAAI Press, Menlo Park, CA, 2006, pp. 68 - 78.). g-Hybrid knowledge bases enable an integration of Description Logics and Logic programming where, unlike in other approaches, variables in the rules of a guarded program do not need to appear in positive non-DL atoms of the body, i.e., DL atoms can act as guards as well. Decidability of satisfiability checking of g-hybrid knowledge bases is shown for the particular DL DLRO-{<=} which is close to OWL DL, by a reduction to guarded programs under the open answer set semantics. Moreover, we show 2-EXPTIME-completeness for satisfiability checking of such g-hybrid knowledge bases.

关键词： g-hybrid knowledge bases open answer set programming guarded logic programs description logics

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An Application of constraint programming to Superblock Instruction Scheduling

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14th international conference on principles and practice of constraint programming (CP 2008)

作者： Malik, Abid M. Chase, Michael Russell, Tyrel van Beek, Peter Univ Waterloo Cheriton Sch Comp Sci Waterloo ON N2L 3G1 Canada

ISBN: (纸本)9783540859574

Modern computer architectures have complex features that Can only be fully taken advantage of if tire compiler schedules the compiled code. A standard region of code for scheduling in an optimizing compiler is called a superblock. Scheduling superblocks optimally is known to be NP-complete, and production compilers rise non-optimal heuristic algorithms. In this paper;we present ill application of constraint programming to the superblock instruction scheduling problem. the resulting system is both optimal and fast enough to be incorporated into production compilers, awl is the first optimal superblock scheduler for realistic architectures. In developing our optimal scheduler, tire keys to scaling up to large;real problems were ill applying and adapting several techniques from the literature including: implied gild dominance constraints, impact-based variable ordering heuristics, singleton bounds consistency, portfolios;and structure-based decomposition techniques. We experimentally evaluated our optimal scheduler oil the SPEC 2000 benchmarks, a standard benchmark suite. Depending oil the architectural model, between 98.29% to 99.98% of all superblocks were solved to optimality. the scheduler was able to routinely solve tire largest superblocks, including superblocks with up to 2,600 instructions, and gave noteworthy improvements over previous heuristic approaches.

关键词： Computer architecture

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principles and practice of constraint programming 2008

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丛书名： Lecture Notes in Computer Science

2008年

作者： Peter J. Stuckey

ISBN: (数字)9783540859581

ISBN: (纸本)9783540859574

this book constitutes the refereed proceedings of the 14th international conference on principles and practice of constraint programming, CP 2008, Sydney, Australia, September, 2008. the 27 revised full papers and 23 revised short papers presented together with 6 application papers and the abstracts of one invited lecture were carefully reviewed and selected from 120 submissions. All current issues of computing with constraints are addressed, ranging from methodological and foundational aspects - using algorithms, environments, languages, models and systems - to solving real-world problems in various application fields.

关键词： constraint programming (Computer science) Congresses.

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constraint based optimization of stationary fields 08

Constraint based optimization of stationary fields

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6th international conference on principles and practice of programming in Java, PPPJ 2008

作者： Rogers, Ian Zhao, Jisheng Kirkham, Chris Watson, Ian University of Manchester Oxford Road Manchester United Kingdom

ISBN: (纸本)9781605582238

In many scenarios a field holds a value that is constant beyond a certain point in the execution of the program. However, Java only allows it to be marked as being final in relation to the control-flow of the program. We present a language extension whereby the programmer can express that a field will have an unchanging value once it satisfies a given constraint. that is the constraint is the guarantee of finality as opposed to the particular code region. A field holding an unchanging value is said to be stationary. the resulting change of the language has similar pitfalls to keywords that express immutability in a dynamic system. However, it provides a number of advantages: ability for improved partial evaluation and specialisation in dynamic compilation, simple inspection to show thread safety and richer information to the runtime environment. We present an implementation of our proposed language extension to Java in the Jikes Research Virtual Machine (RVM). We use class loading as a case study of where lazy initialisation occurs. In code that is frequently executed the probability of a referenced class being uninitialised is less than 1% for method accesses and for fields typically 0%. We create an optimization framework that uses this information to perform specialisation and partial evaluation. We demonstrate that on average 61.32% of accesses occur to fields in their stationary state. We demonstrate that stationary information allows optimizations achieving a best case 3.90% speedup of benchmark applications, and 1.67% speedup on average. © 2008 ACM.

关键词： Java programming language

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Elicitation Strategies for Fuzzy constraint Problems with Missing Preferences: Algorithms and Experimental Studies

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14th international conference on principles and practice of constraint programming (CP 2008)

作者： Gelain, Mirco Pini, Maria Silvia Rossi, Francesca Venable, K. Brent Walsh, Toby Univ Padua Dipartimento Matemat Pura & Applicata I-35100 Padua Italy UNSW NICTA Sydney NSW Australia

ISBN: (纸本)9783540859574

Fuzzy constraints are it popular approach to handle preferences and over-constrained problems in scenarios where one needs to be cautious. Such as in medical or space applications. We consider here fuzzy constraint problems where some of the preferences may be missing. this models, for example, settings where agents are distributed and have privacy issues, or where there is an ongoing preference elicitation process. In this setting. We Study how to find a solution which is optimal irrespective of the missing preferences. In the process of finding such it solution. we may elicit preferences from the user if necessary. However. our goal is to ask the user as little as possible. We define it combined solving and preference elicitation scheme with a large number of different instantiations, each corresponding to a concrete algorithm which we compare experimentally. We compute both the number of elicited preferences and the "user effort", which may he larger, as it contains all the preference values the user has to compute to be able to respond to the elicitation requests. While the number of elicited preferences is important when the concern is to communicate its little information as possible, the user effort measures also the hidden work the user hits to do to be able to communicate the elicited preferences. Our experimental results show that Some of our algorithms are very good at finding a necessarily optimal Solution while asking the user for only a very small fraction of the missing preferences. the user effort is also very small for the best algorithms. Finally, we test these algorithms on hard constraint problems with possibly missing constraints, where the aim is to find feasible solutions irrespective of the missing constraints.

关键词： Space applications

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