Gerard Berry and Gerard Boudol. The chemical abstract machine. In Proceedings of the ACM Symposium on Principles of Programming Languages, pages 81--94. ACM, January 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....do periodic stuff after (0.1 seconds) controller It is important to note that the n execution of this action will have terminated before the (n 1) execution starts. Execution Model The model of concurrent execution used by Timber is based on the idea of the Chemical Abstract Machine [4]. The state of an executing program is envisioned as a soup of molecules. Sometimes these molecules react together, becoming absorbed and producing new molecules as a result. There are two kinds of molecules in the Timber soup : objects and messages. Objects. Objects are always named. The ....

Gerard Berry and Gerard Boudol. The Chemical Abstract Machine. In Seventeenth annual ACM symposium on Principles of programming languages, 1990, San Francisco, CA, USA: ACM Press, .

....fi Figure 2: Structural congruence laws of Calculus A. expressions with respect to an equivalence relation called structural congruence. This setup is familiar in the theory of term rewriting [8] and has been applied to the semantics of concurrent programming in the Chemical Abstract Machine [3] and the Calculus [21] A binary relation j on the expressions of Calculus A is called a congruence if it satisfies the structural congruence laws in Figure 2. Proposition 3.1 The relation E j=j Delta F is a congruence. We define the structural congruence E j F of Calculus A to be the ....

....of the quotient that structural congruence imposes on the set of expressions. The laws for conjunction make conjunction into an operator building multisets of nonconjunctive expressions, where plays the role of the empty multiset. To use the metaphor of the Chemical Abstract Machine [3], conjunction creates the chemical solution in which concurrent computation can take place. The Quantifier Mobility Law SQM and the Renaming Law ensure that quantification does not hinder the flow of the chemical solution. With the congruence laws mentioned so far we can rewrite every expression ....

G'erard Berry and G'erard Boudol. The chemical abstract machine. In Proceedings of the 17th ACM Conference on Principles of Programming Languages, pages 81--94, San Francisco, CA, January 1990.

....does not wish to move, it may spawn a new thread which splits from the agent and then performs the desired move communication. Information thus acquired may be returned to the primary agent later via communication. We discuss this further in Example 3.4 of Section 3. The structural equivalence [4, 22], defined in Figure 3, relates closed systems (N M ) The purpose of the structural equivalence is to abstract from the static structure of terms, i.e. from the irrelevant details of the syntactic relation between composition (P j Q ) restriction ( ne)P ) and location ( JPK) The structural ....

Gerard Berry and Gerard Boudol. The chemical abstract machine. In Conference Record of the ACM Symposium on Principles of Programming Languages, pages 81--94, San Francisco, January 1990. ACM Press. 46 HENNESSY AND RIELY

....functional nets as reduction systems. There is in each case only a single rewrite rule, which is similar to the # reduction rule of # calculus, thus closely matching intuitions of functional programming. By contrast, the original treatment of join calculus is based on a chemical abstract machine[BB90] a concept well established in concurrency theory. The two versions of join calculus complement each other and are (modulo some minor syntactical details) equivalent. 5.1 Purely Functional Calculus Figure 4 presents the subset of join calculus which can express purely functional programs. The ....

Gerard Berry and Gerard Boudol. The chemical abstract machine. In Proc. 17th ACM Symposium on Principles of Programming Languages, pages 81--94, January 1990.

....defined. Processes in C (entities) can use Unix sockets (media) to coordinate. The laws of this model would clearly be laws that govern communication via sockets. Other coordination models include: GAMMA (General Abstract Model for Multiset Manipulation) BL90] CHAM (Chemical Abstract Machine) BB90] IAM (Interaction Abstract Machine) ACP93] LO (Linear Objects) AP92] Manifold [AR93] and Actors [Agh86] Although all the problems of garbage collection and distributed I O also exist in these models this thesis concentrates on the variations of the LINDA model [Gel85] 2.1.1 The LINDA ....

Gerard Berry and Gerard Boudol. The Chemical Abstract Machine. In ACM, editor, Proceedings of the seventeenth annual ACM symposium on Principles of programming languages, pages 81--94, New York, NY, USA, 1990. ACM Press.

....does not wish to move, it may spawn a new thread which splits from the agent and then performs the desired move communication. Information thus acquired may be returned to the primary agent later via communication. We discuss this further in Example 4 of Section 3. The structural equivalence [4, 20], defined in Table 3, relates closed systems (P n Q) The purpose of the structural equivalence is to abstract from the static structure of terms, i.e. from the irrelevant details of the syntactic relation between composition (p E q) restriction ( G ne I p) and location (06C p D ) The ....

Gerard Berry and Gerard Boudol. The chemical abstract machine. In Conference Record of the ACM Symposium on Principles of Programming Languages, pages 81--94, San Francisco, January 1990. ACM Press.

....of a global environment where tuples and processes live together, and agents react to the environment according to some simple rules; for instance, Brownian motion. This analogy has inspired Berry and Boudol to the definition of a concurrent computing model called the Chemical Abstract Machine [4]. This model seems extremely promising for the class of languages listed in the introduction, and in particular for Linda. 4.1 The Chemical Abstract Machine Sequential abstract machines are very useful tools to study sequential programming languages, providing a unified framework to discuss both ....

Gerard Berry and Gerard Boudol. The chemical abstract machine. In Proc. 17 th ACM Conf. on Principles of Programming Languages, pages 81--94, 1990.

....does not wish to move, it may spawn a new thread which splits from the agent and then performs the desired move communication. Information thus acquired may be returned to the primary agent later via communication. We discuss this further in Example 4 of Section 3. The structural equivalence [4, 20], defined in Table 3, relates closed systems (P j Q) The purpose of the structural equivalence is to abstract from the static structure of terms, i.e. from the irrelevant details of the syntactic relation between composition (p j q) restriction ( ne)p) and location ( JpK) The structural ....

Gerard Berry and Gerard Boudol. The chemical abstract machine. In Conference Record of the ACM Symposium on Principles of Programming Languages, pages 81--94, San Francisco, January 1990. ACM Press.

....does not wish to move, it may spawn a new thread which splits from the agent and then performs the desired move communication. Information thus acquired may be returned to the primary agent later via communication. We discuss this further in Example 4 of Section 3. The structural equivalence [4, 20], defined in Table 3, relates closed systems (P Q) The purpose of the structural equivalence is to abstract from the static structure of terms, i.e. from the irrelevant details of the syntactic relation between composition (p j q) restriction ( ne)p) and location ( JpK) The structural ....

Gerard Berry and Gerard Boudol. The chemical abstract machine. In Conference Record of the ACM Symposium on Principles of Programming Languages, pages 81--94, San Francisco, January 1990. ACM Press.

....areas [Bou89, Ode95a, Bou97] As such it seems well suited to take over from lambda calculus as a generally agreed upon foundation of programming. Join calculus has traditionally been introduced as a process calculus, and its operational semantics has been explained as a chemical abstract machine [BB90, FG96] We show in this paper that join calculus can be regarded equivalently as a concurrent version of lambda calculus, with an operational semantics expressed as a reduction system. Our presentation of join calculus has a single reduction rule, similar to # V reduction in the call by value ....

Gerard Berry and Gerard Boudol. The chemical abstract machine. In Proc. 17th ACM Symposium on Principles of Programming Languages, pages 81--94, January 1990.

....the messages are elementary processes that can be sent without any sequencing constraint. Furthermore, names may be restricted, making them private in the context of an agent. 2 These two concepts are sufficient to encode the synchronous communication of the calculus. Chemical Abstract Machine [37]: The chemical abstract machine is a semantic framework based on the chemical metaphor used in the Gamma language of Banatre and Le Metayer. States of a machine are understood as chemical solutions where molecules may interact according to reaction rules. It is possible to dynamically encapsulate ....

G. Boudol and G. Berry, "The chemical abstract machine," Theoretical Computer Science, vol. 96, pp. 217--248, 1992.

....some detail in my thesis [Sar89] and we shall not re make that case here. The purpose of this paper is to explore the higher order analog of the cc languages. We are motivated in part by the obvious need to understand the interaction between concurrency and higher order calculi (see for example [Bou89, Tho90, MPW89, BB90]) in part by the need to understand at a more fundamental level the relationship between the cc programming framework, and Scott s conception of computation, and in part by the need to get a more powerful framework for computing with constraints than provided by the first order cc languages. For ....

Gerard Boudol and G. Berry. The Chemical Abstract Machine. In Proceedings of the 17th Annual ACM Symposium on Principles of Programming Languages, pages 81--94. ACM, 1990.

....class of computational phenomena. In particular, we will develop the concept of linear CCP, which we believe will provide a simple, elegant logical account of various distributed computation models such as the actors formalism of [89] the calculus of [131] the Chemical Abstract Machine of [22], the (intuitionistic) cc languages, and Shared Prolog. One of the primary areas of research in concurrency theory today is the study of higher order process calculii. We will examine higher order concurrent constraint programming languages, with special emphasis on developing higher order ....

Gerard Boudol and G. Berry. The Chemical Abstract Machine. In Proceedings of the 17th Annual ACM Symposium on Principles of Programming Languages, pages 81--94. ACM, 1990.

....as choosing one of the component of A B to verify the sequent within the context Gamma. Since computation is to search for a successful proof, the choice may be influenced by other formulae in Gamma (i.e. the environment) This corresponds to the external choice in concurrent programming [BG90]. Thus, don t care non determinism (committedchoice) for which the arrival nondeterminism is a special case, can be uniformly modelled in terms of additive conjunction. Communication between processes is realised by passing messages, as outlined in the following deduction: Gamma; B;A[t 1 =y] ....

Gerard Boudol and G.Berry. The chemical abstract machine. In Proc. of the 17th Annual ACM symposium on Principle of Programming Languages. ACM, 1990.

....as choicing one of the component of A B to verify the sequent within the context Gamma. Since computation is to search for a successful proof. The choice may be influenced by other formulae in Gamma (i.e. the environment) It corresponds to the external choice in concurrent programming [BG90] Thus, don t care non determinism (committed choice) in concurrent logic programming, where choice is generally made externally, can be uniformly modelled in terms of additive conjunction. Additive Disjunction for Fork: The left rule for additive disjunction Phi Gamma; A Delta Gamma; B ....

.... where the syntax of a receiver is defined as following: m 4 = x(t) singer receiver j m Omega m multiple receivers An intuitive description of the concurrent computation model underlying the calculus may be given following the approach of Berry and Boudol s chemical abstract machine (CHAM) BG90] where the concurrent components in a system are regarded as freely moving in the system and communicate when they come in contact. The state of a system is like a chemical solution in which floating molecules can interact with each other according to reaction rules. Within the calculus, ....

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Gerard Boudol and G.Berry. The chemical abstract machine. In Proc. of the 17th Annual ACM symposium on Principle of Programming Languages. ACM, 1990.

....these ideas lead to the formula as agent interpretation of a larger class of logics. A subset of the formulas of the logic are viewed as computational agents. The left rules in a sequent style presentation of the logic are taken to specify the operational heating rules (in the style of [BB90]) which describe how complex agents may be decomposed into simpler agents, and the basic interactions betwen these agents. Thus, the operational derivability relation between configurations qua agents is related to the entailment relation between configurations qua logical formulas. In general, ....

Gerard Boudol and G. Berry. The Chemical Abstract Machine. In Proceedings of the 17th Annual ACM Symposium on Principles of ProgrammingLanguages, pages 81--94. ACM, 1990.

....multiple shared dataspaces and a more precise interaction protocol. ESP [3] instanciates PoliS and uses Prolog as sequential language. Another family of models merges the coordination mechanisms and the sequential language into a unique formalism, for instance the Chemical Abstract Machine [2] which considers programs as multiset transformations. In a concurrent object oriented framework, we can put forward the Maude language [8] which uses a rewriting logic and the COOLL language [4] that relies on a fragment of linear logic. However, the handling of object oriented principles in ....

G. Berry and G. Boudol. The Chemical Abstract Machine. In Sevententh Annual ACM Symposium on Principles of Programming Languages, pages 81--94, San Francisco, CA., January 1990.

....a process must have free names. The set Proc = fP j fv(P ) g is the set of closed processes. 4. 1 The Reaction Relation The reaction relation is a concise account of computation in the pi calculus introduced by Milner [Mil92] inspired by the Chemical Abstract Machine of Berry and Boudol [BB90]. One thinks of a process as consisting of a chemical solution of molecules waiting to react. A reaction step arises from the interaction of the adjacent molecules mhNi:P and m(x) Q, as follows: mhNi:P j m(x) Q P j Q[N=x] Just as one might stir a chemical solution to allow nonadjacent ....

G. Berry and G. Boudol. The chemical abstract machine. In Conference Record of the Seventeenth ACM Symposium on Principles of Programming Languages, pages 81--94, 1990.

....is written j ff . We also set fu(P ) def = fc(P ) fn(P ) Processes without free variables or free channels are called programs. 2.3. Operational Semantics. For the concise definition of the operational semantics of the language constructs, we introduce the structural equality j (cf. [5, 17]) which is the smallest congruence relation on processes including the following equations. 1. P j Q if P j ff Q. 2. P j inact j P , P j Q j Q j P , P j Q) j R j P j (Q j R) 3. u)inact j inact, uu)P j (u)P , uu 0 )P j (u 0 u)P , u)P j Q j (u) P j Q) if u 62 fu(Q) u)def D in P j def ....

....(b) Fact[b] j y = call b[x Gamma 1] in return[x y] Here and henceforth we write X( x k) P , or a sequence of such equations, for the declaration part of recursion, leaving the body part implicit. This example implements the standard recursive algorithm for the factorial function. y = call f[5] in P would give its client process. The communication patterns based on call return are easily representable by the combination of request accept and send receive. We first show the mapping of the caller. Below [ Delta] denotes the inductive mapping into the structuring primitives. x = call ....

G. Berry and G. Boudol. The chemical abstract machine. TCS, 96:217--248, 1992.

.... the whole system, into a typable local redex (hu ( Ri j uv 1 Delta Delta Delta v k ) the typing of which can be transformed, by a kind of cut elimination, into a typing of Rv 1 Delta Delta Delta v k ) This is not so easy, because typing is not compatible with chemical transformations [4], allowing the components of a parallel system to freely move. Related Work The idea of using trace languages as types is not new. For instance, Abramsky, Gay and Nagarajan [1] developed a semantic framework for types, namely interaction categories, based on this idea. Regular trace ....

....relation P P 0 , the main ingredient being message passing , that is the transformation of uz 1 Delta Delta Delta z n into Rz 1 Delta Delta Delta z n , where R is a resource found for u in the environment, either in a declaration or in a definition. The chemical metaphor (see [4]) would be perfect here, since we want to describe asynchronous computations, where no ordering is assumed on the messages for a given name. However, this style is difficult to maintain with typing purposes, therefore we use a more traditional style, with evaluation contexts. Nevertheless, we ....

G. Berry, G. Boudol, The chemical abstract machine, Theoretical Comput. Sci. 96 (1992) 217-248.

....of receptors) so that j is not a congruence relation, and (b) the relation induced by (ii) iii) and (vi) ix) is finite for a given term. Definition 3 Structural equivalence, denoted by j, is the smallest equivalence relation over terms defined by: 2 Inspired by Chemical Abstract Machine [3]. It can also be likened to the separation of structural rules in Natural Deduction or to the treatment of ff conversion in [2] i) P j Q if P is ff convertible to Q (ii) P; Q) R j P; Q; R) iii) jxjjyjP j jyjjxjP (iv) P; j P (v) jxj j (vi) jxjP; Q j jxj(P; Q) x 62 FN (Q) vii) P; Q ....

Berry, G. and Boudol, G. : The Chemical Abstract Machine. In Proc. 17 the Annual Symposium on Principles of Programming Languages, 1990.

....The work in this paper represents part of a growing interest in higher order process calculi. We feel that it is a significant achievement of Boudol s to describe a calculus that can be given a pleasing mathematical model and yet express concurrency and abstraction. There are other related calculi [13, 19, 4] and also the label passing calculi of Milner and his co workers, studied independently by Engberg and Neilsen [6] Though these systems are theoretical there are other closely related systems, in varying stages of formal analysis, that are actually implemented and are being used in experiments. ....

G. Berry and G. Boudol. The chemical abstract machine. In Proceedings of the 17th Annual ACM Symposium on Principles of Programming Languages, 1990.

....; M) P 0 1 ; M 0 ) P1 P2 ; M) P 0 1 P2 ; M 0 ) 6) P1 ; M) M (P2 ; M) M (P1 P2 ; M) M (7) Fig. 2. An SOS style semantics for Gamma The Gamma model is related to the models of UNITY [12] Action Systems [6, 7] Linda and the Chemical Abstract Machine of Berry and Boudol [11]. All four related formalisms use the metaphor of a chemical reaction as their computational model, although only the latter two use multisets (tuple spaces) as their only data types. The chemical reaction metaphor allows the expression of algorithms which contain a high degree of data ....

G. Berry and G. Boudol. The chemical abstract machine. In 17th Principles of programming languages, pages 81--94, San Fransisco, California, Jan 1990. ACM, New York.

....paper is one of many attempts to find a common theoretical framework for concurrent computation. It would take a long essay to classify these attempts, or even to compare them all to this one. I shall mention only three alternative lines. The chemical abstract machine (CHAM) of Berry and Boudol [6] has common aspects with action structures. Indeed, in particular cases such as the calculus action structure the actions, with a multiset of particles as their principal component, are close to what the natural CHAM for the calculus looks like. Crudely, one can see action structures as an ....

Berry, G. and Boudol, G., The chemical abstract machine, Journal of Theoretical Computer Science, Vol 96, pp217--248, 1992.

....to define a term algebra, and then provide it with reduction rules or transition rules. But for interactive systems it has been found helpful to use a formalism richer than a term algebra. Following ideas of Ban atre and M etayer [4] Berry and Boudol based their Chemical Abstract Machine (Cham) [3] on the notion of multiset. Prompted by them, the present author imposed a structural congruence upon the calculus as part of the formal language, not of the semantics [14] Again, Meseguer and Montanari [10] have revealed the monoidal structure inherent in Petri nets. Indeed, part of the reason ....

....which we shall call action calculi. Their actions are more general than the particle forms discussed in the preceding section; in fact a particle h yiK( x) is a special case of a richer construction which we shall call a molecule. This notion of molecule is similar to that of Berry and Boudol [3]; one difference is that our molecules can bind one another, since a molecule is a name binding operator. The molecules of any action calculus are formed from generators which we shall call control operators, or simply controls. A control operator is a generalisation of the notion of control ....

Berry, G. and Boudol, G., The chemical abstract machine, Journal of Theoretical Computer Science, Vol 96, pp217--248, 1992.

....of information to always hold, given that some other pieces of information must also hold (the notion of entailment) Relationship to other theories of concurrency. Recently there have been radical new ideas about concurrency. Two of particular note are the so called Chemical Abstract Machine [BB90] due to Boudol and Berry, and mobile processes, due to Milner and his co workers [MPW89] In both of these approaches the key new ingredient is that processes can alter their interactions and are, in efffect, mobile. In our approach the interactions between processes is dynamic too in the sense ....

....the closely related safety model and an axiomatization of equality for it. We also believe that it is possible to develop a theory of higher order determinate cc programming languages. There are interesting connections to be made with other theories of higher order concurrent processes [BB90,JP90,Mil90] and also with classical linear logic. It appears that concurrent constraint languages may be related to the proof nets introduced by Girard in his discussion of the proof theory of linear logic. If this connection were successful it would exhibit concurrent constraint programs as ....

G. Boudol and G. Berry. The chemical abstract machine. In Proceedings of the 17th Annual ACM Symposium on Principles of Programming Languages, pages 81--94. ACM, 1990.

....has been the basis for a more general abstract machine for distributed systems called CHARM ( CMR92a, CMR92b] which has been given an algebraic description and has been shown to be able to implement graph grammars, Petri nets, and cc programs. The CHARM is also related to the CHAM machine ([BB90]) which has simpler structural axioms, and which does not exhibit the same convenient treatment of context items and of shared variables. In some sense we can say that, while the CHAM machine models multiset rewriting via the chemical metaphor, the CHARM machine models term (and graph) rewriting ....

G. Berry and G. Boudol. The Chemical Abstract Machine. In Proc. POPL90. ACM, 1990.

....construction. However in order for this construction to work, a limitation of only one defining clause per process is imposed. 4. 3 LL and the Chemical Abstract Machine There is a large body of work close in spirit to the general approach of the Chemical Abstract Machine of Berry and Boudol [32, 36]. This approach regards a system of distributed processes agents objects as a chemical solution where molecules wander around in a Brownian like motion, energised by a magic stirring mechanism. When two matching molecules get in contact with their interlocking (dual) parts, a chemical reaction ....

G. Berry and G. Boudol. The Chemical Abstract Machine. In Principles of Programming Languages (POPL'90), pages 81--94, San Francisco, CA, Jan. 1990. ACM.

....also discuss similar applications of the paradigm as we do here, although their point of view is parallelizability of the approach. Rather, our point of view will be the dynamics of such a system. Later, the idea was further developed into the CHemical Abstract Machine (CHAM) by Berry and Boudol [19]. The CHAM adds new features to the paradigm by considering solutions of multisets and allowing for the definition of membrane like encapsulation of subsolutions. The authors also examine more theoretical aspects of the approach, e.g. its relation to concurrent calculi [20] and to Milner s ....

G. Berry, G. Boudol, The chemical abstract machine, Theor. Comp. Sci., 96 (1992) 217

....a process must have free names. The set Proc = fP j fv(P ) g is the set of closed processes. 4. 1 The Reaction Relation The reaction relation is a concise account of computation in the pi calculus introduced by Milner [Mil92] inspired by the Chemical Abstract Machine of Berry and Boudol [BB90]. One thinks of a process as consisting of a chemical solution of molecules waiting to react. A reaction step arises from the interaction of the adjacent molecules mhNi:P and m(x) Q, as follows: React Inter) mhNi:P j m(x) Q P j Q[N=x] Just as one might stir a chemical solution to allow ....

G. Berry and G. Boudol. The chemical abstract machine. In Conference Record of the Seventeenth ACM Symposium on Principles of Programming Languages, pages 81--94, 1990.

....AR94] In works by Adleman and Arkin and Ross and Hjelmfelt, biochemical reaction networks have been used to implement artificial neuron cells, logic gates and even universal Turing machines. In Computer Science, on the other hand, the chemical computation metaphor is becoming more frequently used [Fon91, BB92, Ban93]. Within this line of research, the potential of computation considered as a kind of chemical reaction taking place between input and output is examined. Here, the flow of data would correspond to the flow of substances and processing of the data, i.e. computation, would correspond to ....

Gerard Berry and Gerard Boudol. The chemical abstract machine. Theor. Computer Science, 96:217--248, 1992.

....Berry showed in [4] Function declarations and their application to data (which can eventually be other functions) is supported by the language. Thus, an important challenge for researchers was to find a framework for the concurrency and the communication between processes similar to the calculus, [1, 5, 7, 10, 11]. We introduce the Parallel Label Selective calculus, LCEP , to model concurrency and communication from a functional perspective. The expressiveness of the calculus is integrated within a unified framework with powerful features to explicitly express the communication actions and the independence ....

G. Berry and G. Boudol. The Chemical Abstract Machine. , pages 81--93, ACM Press, 1993.

....as choosing one of the component of A B to verify the sequent within the context Gamma. Since computation is to search for a successful proof, the choice may be influenced by other formulae in Gamma (i.e. the environment) This corresponds to the external choice in concurrent programming [BG90]. Thus, don t care non determinism (committed choice) for which the arrival nondeterminism is a special case, can be uniformly modelled in terms of additive conjunction. Communication between processes is realized by passing messages, as outlined in the following deduction: Gamma; B; A[t 1 =y] ....

Gerard Boudol and G.Berry. The chemical abstract machine. In Proc. of the 17th Annual ACM symposium on Principle of Programming Languages. ACM, 1990. 10 -- 6 Implementation of Functional Languages '94, UEA, Norwich

....Using the CHAM the state of a system is represented by a chemical solution (a multiset of terms of a word algebra) whose transformation is operationally defined by the application of multiset rewriting (reaction) rules. The CHAM was originally introduced for representing concurrent computations [3]. In fact, the CHAM is also a very simple coordination model to describe and control coordination and interaction among agents [2] All these notations are do not support code mobility. Instead, the PoliS notation allows the specification of code mobility and agent migration in a natural way. ....

G. Berry and G. Boudol. The Chemical Abstract Machine. In Proc. 17 th ACM Conf. on Principles of Programming Languages, pages 81--94, 1990.

....an interesting class of parallel computations. We think the simple operational model can lead to a more practical language core. The resulting framework is strongly related to the paradigm of multiset rewriting lying at the basis of the Gamma formalism [7] and of the Chemical Abstract Machine [9]. Actually it allows to specify a set of transformations that try to reduce an input multiset of goals to the empty multiset, returning as an output an answer substitution for the initial goal. More transformations can be applied concurrently to the multiset, thus making possible efficient ....

..... fragment) with some synchronous additions (the connectives Phi and 1) We believe that LC characterizes a class of applications for a subset of LinLog. Finally we want to mention the relation to [7] and [9]. We think that the LC framework can easily be related to the general model of multiset rewriting. Indeed LC computations realize in a very natural way the chemical metaphor (as first noted in [17] for a smaller fragment) The multiset are solutions in which the molecules (agent or messages) can ....

G. Berry and G. Boudol. The chemical abstract machine. In Proc. Seventeenth Annual ACM Symp. on Principles of Programming Languages, pages 81--94, 1990.

....brought about the juxtaposition x(z) Delta Delta Delta j xy 0 : Delta Delta Delta, which is reducible by the rules which follow below. The use of structural laws such as the above, to bring communicands into juxtaposition, was suggested by the Chemical Abstract Machine of Berry and Boudol [5]. 2.4 Reduction rules This section is devoted to defining the reduction relation over processes; P P 0 means that P can be transformed into P 0 by a single computational step. Now every computation step consists of the interaction between two normal terms. So our first reduction rule is ....

Berry, G. and Boudol, G., The chemical abstract machine, Proc 17th Annual Symposium on Principles of Programming Languages, 1990.

.... Mark Shackleton, and Chris Winter Systems Research BT Laboratories Martlesham Heath Ipswich IP5 3RE UK INTRODUCTION There has been considerable interest in recent years in applying biological metaphors to develop new approaches to information processing (Paton, 1994; Banzhaf et al. 1996; Berry and Boudol, 1992; Fontana, 1991) and in exploiting biochemical processes for computing. At the same time, computational models of cells and cellular systems have attracted increasing attention (Paton, 1993) within both biological and computational spheres. The field of molecular computing (Conrad, 1990; Conrad ....

Berry, G. and Boudol, G., 1992, The chemical abstract machine, Theoretical Computer Science, 96:217.

....first action of the selected E 1 . In order to preserve correctness, the foregoing two operations must be performed atomically [18] Hence, troubles arise for its distributed choice net based modeling [9, 10, 12, 14, 27] centralized choice net based description [16, 17] and CHAM like semantics [2]. The interleaving description of gives a very abstract representation of rivalry because in a distributed environment the competition between two activities a and b, represented by a b, is usually not resolved before the actions start, rather it is resolved by the completion of one of these ....

.... of using P T nets extended with inhibitor arcs is due to the fact that the basic model is not powerful enough to express external nondeterminism and restriction, if we do not make use of the syntactical structure of the terms, as in [8] Because of the equivalence of P T nets with the basic CHAM [2] and the Gamma language [1] we think that also these models can be similarly extended to cope with nondeterminism. As a final comment, we would like to draw some analogy between our approach to net semantics and the so called ask tell coordination mechanism. A shared data space of conflicts ....

G. Berry, G. Boudol, "The Chemical Abstract Machine", Theoretical Computer Science 96, 217-248, 1992.

.... properties [1, 2, 7] As an example Figure 1 shows the information flow in the chemotaxis system of Escherichia Coli [10] In a parallel development, the chemical computation metaphor is becoming more and more frequently used as part of the emergent computation paradigm in Computer Science [3, 4, 5, 6, 8]. In this contribution we will discuss two ways of how information can be processed by a collection of molecules floating around in well stirred tank reactor. In the first case the information is stored as a concentration of a substances and computation is carried out by increase and decrease of ....

G. Berry, G. Boudol, The chemical abstract machine, Theor. Comp. Sci. 96 (1992) 217

....jg Gamma Gamma haijP jQ. We now analyze the originality of our framework with respect to other approaches to the formal analysis of the semantics of generative communication. In (Ciancarini, Jensen, and Yankelevich, 1995) several frameworks such as CCS, Petri Nets and Chemical Abstract Machine (Berry and Boudol, 1992) are used as semantic domains for the coordination language Linda. That paper studies different possible implementations of generative communication in other computational models, but semantic equivalences (and their axiomatizations) are not presented. In (De Nicola and Pugliese, 1995) ....

Berry, G. and Boudol, G. (1992) The chemical abstract machine. Theoretical Computer Science, 96:217-248.

....denotational semantics is fully abstract with respect to a traditional operational semantics. We first describe what is meant by a constraint system and give some basic lemmas that we use later. In the next subsection we give an operational semantics in the style of the Chemical Abstract Machine [3] or CHAM. Finally we sketch the results that show that the program combinators are the functorial image of the logical connectives. An Informal View of Constraint Systems What do we have when we have a constraint system First, of course, there must be a vocabulary of assertions that can be made ....

G. Berry and G. Boudol. The chemical abstract machine. In Proceedings of the Seventeenth Annual ACM Symposium on Principles of Programming Languages, pages 81--94. ACM, 1990.

....floating molecules. 3 The molecules are equations, abstractions, applications, conditionals, and cells. The structural congruence of the fl calculus is defined such 3 The metaphor of seeing concurrent computation as chemical reaction appeared with Berry and Boudol s chemical abstract machine [4]. Structure E j E 0 E 0 F 0 F 0 j F E F E E 0 E F E 0 F E E 0 9uE 9uE 0 Elimination 9x(x = u E) E[u=x] if x 6= u and u free for x in E Application au a: x=E E[u=x] a: x=E if u free for x in E and juj = jxj Conditional if u = u then E else F E if a = b ....

G. Berry and G. Boudol. The chemical abstract machine. In Proceedings of the 17th ACM Conference on Principles of Programming Languages, pages 81--94, 1990.

....that Reppy gives it in CML. As a result, we now have a semantics for the basic primitives of CML. Thus for semantic reasons we have arrived at the same result as Reppy, who used purely pragmatic reasoning. Our semantics has been influenced by Facile [GMP89] and the Chemical Abstract Machine [BB90]. However, we believe that our approach is simpler. For example, Facile can create a new process with either a behaviour expression or a fork function, and this results in some transitions being labelled with behaviour expressions. We avoid the need for such complex labels by eliminating behaviour ....

G. Berry and G. Boudol. The chemical abstract machine. In Proceedings of the Seventeenth ACM Symposium on Principles of Programming Languages, 1990.

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Gerard Berry and Gerard Boudol. The chemical abstract machine. In Proceedings of the ACM Symposium on Principles of Programming Languages, pages 81--94. ACM, January 1990.

No context found.

Gerard Berry and Grard Boudol. The chemical abstract machine. In Proceedings of the 17th ACM SIGPLAN-SIGACT symposium on Principles of programming laguages (POPL'90), pages 81--94. ACM Press, 1990.

No context found.

Gerard Berry and Gerard Boudol. The Chemical Abstract Machine. In ACM, editor, Proceedings of the seventeenth annual ACM symposium on Principles of programming languages, pages 81--94, New York, NY, USA, 1990. ACM Press.

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Berry, G., and Boudol, G. "The chemical abstract machine". Theor. Comp. Sci. 96 (1992), 217-248.

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Berry, G., and Boudol, G. "The Chemical Abstract Machine". ACM POPL 17, San Francisco, CA, Jan. 1990,81-94.

No context found.

G. Berry and G. Boudol. The chemical abstract machine. In 17th ACM Annual Symposium on Principles of Programming Languages, pages 81--94, New York, 1990. ACM Press.

No context found.

Berry, G., and g. Boudol. The chemical abstract machine. In Proc. 17th ACM Symp. Principles of Programming Languages (1990), pp. 81--94.

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