| 1. |
- Haridi, Seif, et al.
(författare)
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Efficient logic variables for distributed computing
- 1999
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Ingår i: ACM Transactions on Programming Languages and Systems. - : Association for Computing Machinery (ACM). - 0164-0925 .- 1558-4593. ; 21:3, s. 569-626
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Tidskriftsartikel (refereegranskat)abstract
- We define a practical algorithm for distributed rational tree unification and prove its correctness in both the off-line and on-line cases. We derive the distributed algorithm from a centralized one, showing clearly the trade-offs between local and distributed execution. The algorithm is used to realize logic variables in the Mozart Programming System, which implements the Oz language (see http://www.mozart-oz.org). Oz appears to the programmer as a concurrent object-oriented language with dataflow synchronization Logic variables implement the dataflow behavior. We show that logic variables can easily be added to the more restricted models of Java and ML, thus providing an alternative way to do concurrent programming in these languages. We present common distributed programming idioms in a network-transparent way using logic variables. We show that in common cases the algorithm maintains the same message latency as explicit message passing. In addition, it is able to handle uncommon cases that arise from the properties of latency tolerance and third-party independence. This is evidence that using logic variables in distributed computing is beneficial at both the system and language levels. At the system level, they improve latency tolerance and third-party independence. At the language level, they help make network-transparent distribution practical.
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| 2. |
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| 3. |
- Schulte, Christian, 1967-, et al.
(författare)
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Encapsulated Search and Constraint Programming in Oz
- 1994
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Ingår i: Second International Workshop on Principles and Practice of Constraint Programming. - : Springer-Verlag. ; , s. 134-150
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Konferensbidrag (refereegranskat)
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| 4. |
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| 5. |
- Tack, Guido, et al.
(författare)
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Generating propagators for finite set constraints
- 2006
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Ingår i: Principles And Practice Of Constraint Programming - CP 2006. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 3540462678 ; , s. 575-589
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Konferensbidrag (refereegranskat)abstract
- Ideally, programming propagators as implementations of constraints should be an entirely declarative specification process for a large class of constraints: a high-level declarative specification is automatically translated into an efficient propagator. This paper introduces the use of existential monadic second-order logic as declarative specification language for finite set propagators. The approach taken in the paper is to automatically derive projection propagators (involving a single variable only) implementing constraints described by formulas. By this, the paper transfers the ideas of indexicals to finite set constraints while considerably increasing the level of abstraction available with indexicals. The paper proves soundness and completeness of the derived propagators and presents a run-time analysis, including techniques for efficiently executing projectors for n-ary constraints.
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| 6. |
- Van Roy, Peter, et al.
(författare)
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A history of the Oz multiparadigm language
- 2020
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Ingår i: Proceedings of the ACM on Programming Languages. - : Association for Computing Machinery. - 2475-1421. ; 4:HOPL
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Tidskriftsartikel (refereegranskat)abstract
- Oz is a programming language designed to support multiple programming paradigms in a clean factored way that is easy to program despite its broad coverage. It started in 1991 as a collaborative effort by the DFKI (Germany) and SICS (Sweden) and led to an influential system, Mozart, that was released in 1999 and widely used in the 2000s for practical applications and education. We give the history of Oz as it developed from its origins in logic programming, starting with Prolog, followed by concurrent logic programming and constraint logic programming, and leading to its two direct precursors, the concurrent constraint model and the Andorra Kernel Language (AKL). We give the lessons learned from the Oz effort including successes and failures and we explain the principles underlying the Oz design. Oz is defined through a kernel language, which is a formal model similar to a foundational calculus, but that is designed to be directly useful to the programmer. The kernel language is organized in a layered structure, which makes it straightforward to write programs that use different paradigms in different parts. Oz is a key enabler for the book Concepts, Techniques, and Models of Computer Programming (MIT Press, 2004). Based on the book and the implementation, Oz has been used successfully in university-level programming courses starting from 2001 to the present day.
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| 7. |
- Van Roy, Peter, et al.
(författare)
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Mobile objects in distributed Oz
- 1997
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Ingår i: ACM Transactions on Programming Languages and Systems. - : Association for Computing Machinery (ACM). - 0164-0925 .- 1558-4593. ; 19:5, s. 804-851
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Tidskriftsartikel (refereegranskat)abstract
- Some of the most difficult questions to answer when designing a distributed application are related to mobility: what information to transfer between sites and when and how to transfer it. Network-transparent distribution, the property that a program's behavior is independent of how it is partitioned among sites, does not directly address these questions. Therefore we propose to extend all language entities with a network behavior that enables efficient distributed programming by giving the programmer a simple and predictable control over network communication patterns. In particular, we show how to give objects an arbitrary mobility behavior that is independent of the object's definition. In this way, the syntax and semantics of objects are the same regardless of whether they are used as stationary servers, mobile agents, or simply as caches, These ideas have been implemented in Distributed Oz, a concurrent object-oriented language that is state aware and has dataflow synchronization. We prove that the implementation of objects in Distributed Oz, is network transparent. To satisfy the predictability condition, the implementation avoids forwarding chains through intermediate sites. The implementation is an extension to the publicly available DFKI Oz 2.0 system.
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| 8. |
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