J. Niehren and M. Mueller. Constraints for free in concurrent computation. In Proceedings of the Asian Computer Science Conference, LNCS 1023, pages 171-186, 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....parent process and let them escape through Y. Rather, we want to allocate and garbage collect them locally and let Y emit an integer constant. 9 Related Work Relating the family of # calculi and the CCP formalism has been done as proposals of calculi such as the # calculus [33] the # calculus [24] and the Fusion calculus [48] all of which incorporate constraints (or name equation) in some form. The # calculus is unique in that it uses procedures with encapsulated states to model concurrency and communication rather than the other way around. The # calculus introduces constraints into ....

Niehren, J. and Muller, M., Constraints for Free in Concurrent Computation. In Proc. Asian Computing Science Conf. (ACSC'95), LNCS 1023, Springer-Verlag, 1995, pp. 171--186.

....denotable objects in the programming language, called constraints, can be constructed, and an entailment relation specifying interdepencies between such constraints. For our purposes it will suffice to found the notion of constraint system on First Order Predicate Logic (PL) as it was done in ( NM95] Smo94] A more general and foundationally less heavy alternative for setting up the notion is given in [SRP91] by representing constraint systems as Scott s information systems [Sco82] without consistency structure. The importance of this alternative is that information systems form a rich ....

Joachim Niehren and M Martin. Constraints for free in concurrent computation. In Kanchana Kanchanasut and Jean-Jaques Levy, editors, Asian Computing Science Conference, volume 1023 of Lecture Notes in Computer Science, pages 171--186, December 1995.

....del Valle, ciudad universitaria Mel endez, Cali, Colombia GERARD ASSAYAG assayag ircam.fr IRCAM, 1 pl Igor Stravinski, 75004 Paris, France Abstract. We propose PiCO, a calculus integrating concurrent objects and constraints, as a base for music composition tools. In contrast with calculi such as [5], 9] or TyCO [16] both constraints and objects are primitive notions in PiCO.InPiCO a base object model is extended with constraints by orthogonally adding the notion of constraint system found in the # calculus [12] Concurrent processes make use of a constraint store to synchronize ....

....constraints can also be used to define a rich set of possible concurrent processes interactions, as has been shown in the cc model [11] The basic operations ask and tell allow processes to define complex synchronization schemes through the use of common process variables. In the cc language Oz [5], first class procedures and first class cells are used to simulate objects within a concurrent constraint setting. Objects are thus INTEGRATING CONSTRAINTS 23 not primitive. In fact, the constraint paradigm is the only underlying model of interaction. The powerful constraints calculus of Oz ....

N. Joachim and M. Muller (1995). "Constraints for Free in Concurrent Computation." Asian Computing Science Conference. K. Kanchanasut and J.-J. Levy, editors, pages 171--186, Pathumthani, Thailand.

....Indeed a computation is possible when two objects interact and evolve generating other interaction or modifying their environments via substitutions. We also address the issue of encoding concurrent computations by showing as an example how the fusion calculus [9] and hence [7] 10] and [8] calculi) can be expressed in our formalism. Finally we propose an encoding of proof nets in the calculus and we introduce the question of typing in relation with linear logic. The paper is organized as follows. In the next section we introduce the basic ingredients of our calculus. Section 3 ....

J. Niehren and M. Muller. Constraints for free in concurrent computations. In In Proc. of ACSC95, LNCS 1023, pages 171-186, 1995.

....that also simplifies the p calculus, by taking a different approach, in which both input and output are symmetric as in fusion, but unlike fusion, they are binding operators. Other calculi relevant to concurrent constraint programming include Smolka s g calculus, and Niehren and Mller s r calculus [NM95]. Conclusion It s agreeable that the fusion calculus is more elegant than p calculus since it is simpler and more orthogonal, having symmetric input and output operations, and only one binding operator. The authors also argue that there is only one sensible bisimulation equivalence, so the ....

Niehren, J., Mller, M. Constraints for Free in Concurrent Computation. In Proceedings of ACSC'95. LNCS. Springer-Verlag, December 1995.

....Journal 1 (2) 1998 2 The need to establish a firm base for the integration of programming models has led to the design of formal calculi for a variety of paradigms. One approach in this direction is to devise a calculus for a particular paradigm and then show how to simulate the others in it [JM95]. A more direct approach is to include the notions of the integrated paradigms in a new calculus [Vas94] In our quest for the foundations of a computer music language we favor the strategy of relying on minimal orthogonal extensions to calculi that have already found an established place in the ....

N. Joachim and M. Muller. Constraints for Free in Concurrent Computation. In Kanchana Kanchanasut and Jean-Jacques L'evy, editors, Asian Computing Science Conference, Lecture Notes in Computer Science, vol. 1023, pages 171--186, Pathumthani, Thailand, December 1995. SpringerVerlag.

.... calculus. Furthermore, the call by need complexity is dominated by call byvalue complexity. In contrast to the recently proposed call by need calculus, the concurrent call by need model of [67] incorporates mutual recursion and can be extended to cyclic data structures by means of constraints. [68] investigates concurrency as unifying computational paradigm which integrates functional, constraint, and object oriented programming. The ae calculus is proposed as a foundation of concurrent computation. The ae calculus with equational constraints provides for logic variables and is bisimilar ....

Joachim Niehren and Martin Muller. Constraints for free in concurrent computation. In International Workshop on Concurrent Constraints Programming, Venice, Italy, May 1995.

.... however, Milner has given a reduction semantics that is much simpler that the rather delicate SOS definitions of labelled transition systems [Mil92] Following this, more recent name passing process calculi have often been defined by a reduction semantics in some form, e.g. the HO [San93] ae [NM95], Join [FG96] Blue [Bou97] Spi [AG97] dpi [Sew98] D [RH98] and Ambient [CG98] Calculi. Turning to operational congruences, for confluent calculi the definition of an appropriate operational congruence is relatively straightforward, even in the (usual) case where the dynamics is expressed as a ....

J. Niehren and M. Mueller. Constraints for free in concurrent computation. In Proceedings of the Asian Computer Science Conference, LNCS 1023, pages 171--186, 1995.

.... on [14] however, Milner has given a reduction semantics that is much simpler than the rather delicate SOS de nitions of labelled transition systems [28] Following this, more recent name passing process calculi have often been de ned by a reduction semantics in some form, e.g. the HO [35] [32], Join [17] Blue [9] Spi [1] dpi [39] D [34] and Ambient [10] Calculi. Turning to operational congruences, for con uent calculi the de nition of an appropriate operational congruence is relatively straightforward, even in the (usual) case where the dynamics are expressed as a reduction ....

J. Niehren and M. Mueller. Constraints for free in concurrent computation. In Proceedings of the Asian Computer Science Conference, LNCS 1023, pages 171-186, 1995.

....Italy fpriami,solitrog sci.univr.it 14 April 2000 1 Introduction Many process calculi have been proposed in the literature in the last years to address the description of distributed and communicating systems. Various mechanisms of interaction between processes have been devised as basic [8, 9, 12, 10, 5, 4]. We resort in this paper to an interaction mechanism inspired to the computational behaviour of proof nets, a deduction system of linear logic [7] In this setting the conclusion of a derivation is the type of the corresponding proof net. The computational mechanism is cut elimination that can ....

.... (represented by a variable) with something else (a process) We show here that designing systems in a multiset style and equipping them with a simple interaction mechanism is enough to express the computations of the calculus [2] of the fusion calculus [11] and hence [9] fl [12] and ae [10] calculi) and of the proof nets [7] 2 The basic calculus In this section we introduce our calculus. We first define its syntax and then its operational semantics. Finally, we discuss confluence properties of the calculus. 2.1 Syntax Definition 2.1. Let V be a denumerable set of variables ....

J. Niehren and M. Muller. Constraints for free in concurrent computations. In In Proc. of ACSC95, LNCS 1023, pages 171--186, 1995.

....17 and x ) An example of a concurrent constraint computation is CC program: ask (x y) P tell (y 17) tell (x 11) which can evolve into P with a store which entails x 11 y 17. To relate mobile process calculi and concurrent constraints, we use the ae calculus of Niehren and Muller [6]. This is a calculus which serves as a foundation of the concurrent constraint programming language Oz, developed at DFKI in Saarbrucken. Oz incorporates constraints, functional, and object oriented programming in a concurrent setting, and requires a richer foundational calculus than a pure ....

....developed at DFKI in Saarbrucken. Oz incorporates constraints, functional, and object oriented programming in a concurrent setting, and requires a richer foundational calculus than a pure constraint calculus as in, e.g. 11] The process part of the ae calculus is a subcalculus of the calculus [6], and it is expressive enough to model functional and object oriented programming. It can be extended by an arbitrary constraint system CS, resulting in the calculus ae(CS) This takes the calculus beyond traditional process calculi and it thus cannot directly use the rich flora of associated ....

[Article contains additional citation context not shown here]

J. Niehren and M. Muller. Constraints for free in concurrent computation. In K. Kanchanasut and J.-J. L'evy, editors, Asian Computer Science Conference, volume 1023 of LNCS, pages 171--186. Springer, 1995.

....calculus has a higher degree of symmetry and this has profound implications for our technical proofs. In [21] we explore the weak version of the equivalence defined in the present paper, give a reduction semantics of the fusion calculus, and show how to encode three variants of the ae calculus [9], a foundational calculus for concurrent constraints. Another way to obtain an input output symmetry is in the I calculus developed by Sangiorgi [16] I is a subcalculus of : output objects must be bound by restriction, so both input and output bind their objects. Through clever encodings it has ....

J. Niehren and M. Muller. Constraints for free in concurrent computation. In K. Kanchanasut and J.- J. L'evy, editors, Asian Computer Science Conference, volume 1023 of LNCS, pages 171--186, Pathumthani, Thailand, 11--13 Dec. 1995. Springer.

....nor too picky in that it takes insignificant aspects into consideration. Related work: Smolka [Smo94] inspired our research by relating the fl calculus to a variant of the calculus with variables, equations and an elimination rule. We show that these additions can be dropped. Niehren and Muller [NM95] relate the fl calculus to the ae calculus with equational constraints (ae(x = y) and observe that the ae calculus without constraints (ae( is a subcalculus both of ae(x = y) and of the calculus. We strengthen their result by formally showing the correspondence between the fl calculus and ....

....into the calculus and established its correctness by means of barbed bisimulation congruence. This opens several avenues of further work. The constraints in the fl calculus are just equalities between variables and names. In this way fl is equipotent with a special case of the ae calculus[NM95] A natural direction for further work is to investigate other versions of the ae calculi and the Oz calculus. These calculi use constraints over arbitrary data types and although data type encodings in the calculus are well understood it is less clear how to deal with constraints over them. ....

J. Niehren and M. Muller. Constraints for free in concurrent computation. In K. Kanchanasut and J.-J. L'evy, editors, Asian Computing Science Conference on Algorithms, Concurrency and Knowledge (ACSC '95), volume 1023 of Lecture Notes in Computer Science, Pathumthani, Thailand, 11--13 Dec. 1995. Springer-Verlag.

....too picky in that it takes insignificant aspects into consideration. Related work: Smolka [Smo94] inspired our research by relating the fl calculus to a variant of the calculus with variables, equations and an elimination rule. We show that these additions can be dropped. Niehren and Muller [NM95] relate the fl calculus to the ae calculus with equational constraints (ae(x = y) and observe that the ae calculus without constraints (ae( is a subcalculus both of ae(x = y) and of the calculus. We strengthen their result by formally showing the correspondence between the fl calculus and ....

....into the calculus and established its correctness by means of barbed bisimulation congruence. This opens several avenues of further work. The constraints in the fl calculus are just equalities between variables and names. In this way fl is equipotent with a special case of the ae calculus[NM95] A natural direction for further work is to investigate other versions of the ae calculi and the Oz calculus. These calculi use constraints over arbitrary data types and although data type encodings in the calculus are well understood it is less clear how to deal with constraints over them. ....

J. Niehren and M. Muller. Constraints for free in concurrent computation. In K. Kanchanasut and J.-J. L'evy, editors, Asian Computing Science Conference on Algorithms, Concurrency and Knowledge (ACSC '95), volume 1023 of Lecture Notes in Computer Science, Pathumthani, Thailand, 11--13 December 1995. Springer-Verlag.

....resulting higher order ccp model is simple and theoretically clean. Its restriction to the pure functional paradigm recovers nice formal properties such as confluence [28] both in the lazy and eager cases. For a deeper introduction, see the Oz programming model [41] and the calculi underlying Oz [40, 29, 28]. A closely related model of concurrency is the calculus [25] See [28] for a formal comparison between the two models. The higher order ccp core is minimally extended with state and search (see Section 5) The programming style arising from the resulting model can be sketched as follows: ....

.... Programming Model This section briefly summarizes the ingredients of the Oz Programming Model OPM with its extension by encapsulated search, and relates them to the programming abstractions above [41] For more background, see [40, 42, 18, 38] The paradigms are compared on the calculus level in [29, 28]. Concurrent Constraints. The core of OPM is similar to Saraswat s concurrent constraint model [37] providing for concurrent control and synchronization via logic variables. E : local x in E end j E F j C j if C then E else F fi C : x = y j x = f(y) j : Computation in OPM takes place ....

Joachim Niehren and Martin Muller. Constraints for Free in Concurrent Computation. In Asian Computer Science Conference, Pathumthani, Thailand, 11--13 December 1995. Springer-Verlag, Berlin, Germany. LNCS, to appear.

.... however, Milner has given a reduction semantics that is much simpler that the rather delicate SOS definitions of labelled transition systems [Mil92] Following this, more recent name passing process calculi have often been defined by a reduction semantics in some form, e.g. the HO [San93] ae [NM95], Join [FG96] Blue [Bou97] Spi [AG97] dpi [Sew98b] D [RH98] and Ambient [CG98] Calculi. Turning to operational congruences, for confluent calculi the definition of an appropriate operational congruence is relatively straightforward, even in the (usual) case where the dynamics is expressed as ....

J. Niehren and M. Mueller. Constraints for free in concurrent computation. In Proceedings of the Asian Computer Science Conference, LNCS 1023, pages 171--186, 1995.

....17 and x ) An example of a concurrent constraint computation is CC program: ask(x y) P tell(y 17) tell(x 11) which can evolve into P with a store which entails x 11 y 17. To relate mobile process calculi and concurrent constraints, we use the ae calculus of Niehren and Muller [NM95]. This is a calculus which serves as a foundation of the concurrent constraint programming language Oz, developed at DFKI in Saarbrucken. Oz incorporates constraints, functional, and object oriented programming in a concurrent setting, and requires a richer foundational calculus than a pure ....

....at DFKI in Saarbrucken. Oz incorporates constraints, functional, and object oriented programming in a concurrent setting, and requires a richer foundational calculus than a pure constraint calculus as in, e.g. SRP91] The process part of the ae calculus is a subcalculus of the calculus [NM95], and it is expressive enough to model functional and object oriented programming. It can be extended by an arbitrary constraint system CS, resulting in the calculus ae(CS) This takes the calculus beyond traditional process calculi and it thus cannot directly use the rich flora of associated ....

[Article contains additional citation context not shown here]

J. Niehren and M. Muller. Constraints for free in concurrent computation. In K. Kanchanasut and J.-J. L'evy, eds, Asian Computer Science Conference, volume 1023 of LNCS, pages 171--186. Springer, 1995.

....checking a program consists in three steps: i) every program variable is mapped to a type variable, ii) the program itself is mapped to a constraint OE over these variables, and (iii) inconsistency of OE is interpreted as a type error. Consider the following program written in the ae calculus [NM95]. The ae calculus can be considered as relational calculus [Nie94] or as concurrent calculus [MPW92] with logic variables. Furthermore, it is a foundation for concurrent constraint programming [Smo94] in the style of Oz. This program declares four variables x; y; z, and p. It defines a ....

Joachim Niehren and Martin Muller. Constraints for Free in Concurrent Computation. In First International Workshop on Concurrent Constraint Programming, Venice, Italy, May29--31 1995. Submitted to CP'95.

.... computational paradigm in the spirit of Milner [Mil92] and Smolka [Smo94, Smo95b] Whereas the motivations for both approaches are quite distinct, the resulting formalisms are closely related: The calculus [MPW92] models communication and synchronisation via channels, whereas the ae calculus [NS94, Smo94, NM95] uses logic variables or more generally constraints as inspired by [Mah87, SRP91] Our motivation in concurrent calculi lies in the design of programming languages. Concurrency enables us to integrate multiple programming paradigms such as functional [Mil92, Smo94, Nie94, Iba95, PT95b] ....

....of functional arguments and evaluates only needed arguments. As a formal basis, we use a uniformly confluent applicative core of a concurrent calculus that we call ffi 0 calculus. This is a proper subset of the polyadic asynchronous calculus [Mil91, HT91, Bou92] and of the ae calculus [NM95, Smo94], the latter being a foundation of higher order concurrent constraint programming. The choice of ffi 0 has the following advantages: 1. Delay and triggering mechanisms as needed for programming laziness are expressible within ffi 0 . 2. Mutually recursive definitions are expressible in a callby ....

[Article contains additional citation context not shown here]

Joachim Niehren and Martin Muller. Constraints for Free in Concurrent Computation. In Asian Computing Science Conference, LNCS, December 1995.

.... computational paradigm in the spirit of Milner [Mil92] and Smolka [Smo94, Smo95b] Whereas the motivations for both approaches are quite distinct, the resulting formalisms are closely related: The calculus [MPW92] models communication and synchronisation via channels, whereas the ae calculus [NS94, Smo94, NM95] uses logic variables or more generally constraints as inspired by [Mah87, SRP91] Our motivation in concurrent calculi lies in the design of programming languages. Concurrency enables us to integrate multiple programming paradigms such as functional [Mil92, Smo94, Nie94, Iba95, PT95b] ....

....of functional arguments and evaluates only needed arguments. As a formal basis, we use a uniformly confluent applicative core of a concurrent calculus that we call ffi 0 calculus. This is a proper subset of the polyadic asynchronous calculus [Mil91, HT91, Bou92] and of the ae calculus [NM95, Smo94], the latter being a foundation of higher order concurrent constraint programming. The choice of ffi 0 has the following advantages: 1. Delay and triggering mechanisms as needed for programming laziness are expressible within ffi 0 . Originally, Smolka s fl calculus [Smo94] and the ae calculus ....

[Article contains additional citation context not shown here]

Joachim Niehren and Martin Muller. Constraints for Free in Concurrent Computation. In Asian Computing Science Conference, Lecture Notes in Computer Science, pages 171-186, Springer-Verlag. Pathumthani, Thailand, December 1995.

....independent of the other data structures. 12 6 Related Work Earlier work that compared higher order concurrent constraint programming and the p calculus includes the following. Smolka [36] presents OPM in form of the g calculus, and notices a close relation to the p calculus. Niehren and Muller [27] prove this relation based on the r calculus which extends the g calculus with a parametric constraint system. Niehren [25, 26] studies uniform confluence in the concurrent calculi mentioned above (g, d, r, p, join) he identifies a common subcalculus of g and p and proves that it can embed the ....

J. Niehren and M. Muller. Constraints for free in concurrent computation. In K. Kanchanasut and J.-J. Levy, eds, 1 Asian Computing Science Conference, LNCS 1023, pp. 171--186. Springer-Verlag, Berlin, 1995.

....complexity ) This implementation can be organized incrementally. Type Analysis. One application for INES constraints which we are investigating in [23] is type analysis for concurrent constraint programming [17, 27] in particular Oz [28] As formal foundations we intend to use the calculi in [24, 25]. There, INES constraints are used to approximate the set of run time values for program variables. Since values in Oz include infinite trees, it is important that INES allows an interpretation over sets of possibly infinite trees. It is considered an error if the set of possible run time values ....

J. Niehren and M. Muller. Constraints for Free in Concurrent Computation. In ASIAN, LNCS 1023, pp. 171--186. Springer, 1995.

....higherorder ccp model is simple and theoretically clean. Its restriction to the pure functional paradigm recovers nice formal properties such as confluence [Nie96] both in the lazy and eager cases. For a deeper introduction, see the Oz programming model [Smo95a] and the calculi underlying Oz [Smo94, NM95b, Nie96]. A closely related model of concurrency is the calculus [Mil93] See [Nie96] for a formal comparison between the two models. 2 The non declarative aspect has received some attention, e.g. Nai86, HL94, PS95, And95] 3 The higher order ccp core is minimally extended with state and search ....

.... This section briefly summarizes the ingredients of the Oz Programming Model OPM with its extension by encapsulated search, and relates them to the programming abstractions above [Smo95a] For more background, see [Smo94, Smo95b, HSW95, SS94] The paradigms are compared on the calculus level in [NM95b, Nie96]. Concurrent Constraints. The core of OPM is similar to Saraswat s concurrent constraint model [Sar93] providing for concurrent control and synchronization via logic variables. E : local x in E end j E F j C j if C then E else F fi C : x = y j x = f(y) j : Computation in OPM takes ....

Joachim Niehren and Martin Muller. Constraints for Free in Concurrent Computation. In Asian Computer Science Conference, Pathumthani, Thailand, 11--13 December 1995. Springer-Verlag, Berlin, Germany. LNCS, to appear.

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J. Niehren and M. Muller. Constraints for free in concurrent computation. In International Workshop on Concurrent Constraints Programming, Venice, Italy, May29--31 1995.

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J. Niehren and M. Mueller. Constraints for free in concurrent computation. In Proceedings of the Asian Computer Science Conference, LNCS 1023, pages 171-186, 1995.

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J. Niehren and M. Mueller. Constraints for free in concurrent computation. In Proceedings of the Asian Computer Science Conference, LNCS 1023, pages 171--186, 1995.

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J. Niehren and M. Mueller. Constraints for free in concurrent computation. In Proceedings of the Asian Computer Science Conference, LNCS 1023, pages 171--186, 1995.

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J. Niehren and M. Mueller. Constraints for free in concurrent computation. In Asian Computing Science Conference, LNCS 1023:171--186, 1995. ftp: //ps-ftp.dfki.uni-sb.de/pub/papers/ProgrammingSysLab/ConstraintsFree.ps.Z

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