S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....tries to bind a variable to different values (non deterministic binding to compute potential solutions) while its corresponding twin thread is already active. The latter case avoids the duplication of processes for don t know non deterministic computations which is also known as stability from AKL [15]. This scheme implements coroutining features of current Prolog systems [18] as well as features of concurrent constraint languages [22] In the next section, we review the basic computation model of Curry. Its concurrent implementation in Java is described in Section 3. Section 4 discusses some ....

....between sequential and concurrent computations supports the use of efficient and optimal evaluation strategies for the sequential parts, where similar techniques for the concurrent parts are not available. This is in contrast to other, more fine grained concurrent computation models like AKL [15], CCP [22] or Oz [23] 3 Implementation of Curry Programs In this section we sketch a Java based implementation of an abstract machine for executing Curry programs. We describe the implementation of data terms, defined functions, and the computational model of Curry (variable bindings, ....

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S. Janson and S. Haridi. Programming paradigms of the Andorra Kernel Language. In Proc. 1991.

....for example in the store fX 2 f1; 2g; Y 2 f3; 4gg the monotone constraint X in : max(Y ) is entailed without being detected such by Table 4. Only when Y is determined the constraint will be decided entailed (see Section 4. 3) This scheme has been implemented in the AKL system, developed at SICS [7], and preliminary results indicate an eciency comparable with clp(FD) cc(FD) and CHIP [1] 4.2 Generating entailment checking indexicals In this section we show how to use the entailment detection in Section 4 for checking the entailment conditions of Section 3.1. We adapt Table 2 and Table 3 ....

S. Janson and S. Haridi. Programming paradigms of the Andorra Kernel Language. In Logic Programming: Proceedings of the 1991.

....domain) constraint programming (cf. cardinality constraints [HD91, MPSW94] Note that these propagation techniques are impossible to apply to a non incremental algorithm. By design, the whole algorithm is suitable for integration into a concurrent constraint language like Oz [Smo95] or AKL [JH91] and allows us to understand type checking as a application of constraint programming. Related Work. The containment relation turns out to be equivalent to weak subsumption which was introduced by Dorre [Dor94] as an approximation of the undecidable (strong) subsumption [DR90] between feature ....

Sverker Janson and Seif Haridi. Programming Paradigms of the Andorra Kernel Language. In International Logic Programming Symposium, pp. 167--186, 1991.

....the notion of committed choice. At first, the new model developed as an ad hoc construction, but finally Maher [18] realized that commitment of agents can be captured logically as constraint entailment. The first practical language design combining committed choice with encapsulated search is AKL [14]. AKL s primary mechanism for encapsulation of nondeterminism are deep guards. In 1991 the DFKI started the research project Hydra with the goal to design, investigate and implement a high level concurrent programming language bringing together the merits of logic and object oriented programming. ....

Sverker Janson and Seif Haridi. Programming paradigms of the Andorra kernel language. In Vijay Saraswat and Kazunori Ueda, editors, Logic Programming, Proceedings of the 1991.

....i.e. yields more than one goal, the entire process structure is copied. Although this is necessary to compute all solutions, it could be more ecient to perform a non deterministic step only if a deterministic step in another thread is not possible. This strategy corresponds to stability in AKL [14] and Oz [20] and could also be speci ed in our framework without any problem. We conjecture that is con uent up to variable renaming because the heap can only be extended. If the variable bindings of di erent threads in the shared heap clash, then this will happen in any scheduling policy ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Proc. 1991.

....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] object oriented [Vas94, PT95a, HSW95, Wal95] and constraint programming [JH91, SSW94]. All these paradigms are supported by the programming language Oz [Smo95a, Smo95b] In this paper, we model the time complexity of eager and lazy functional computation in a concurrent calculus. The importance of complexity is three fold: 1. Every implementation oriented model has to reflect ....

Sverker Janson and Seif Haridi. Programming paradigms of the Andorra Kernel Language. In Proceedings of the International Symposium on Logic Programming, pages 167--186, 1991.

....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] object oriented [Vas94, PT95a, HSW95, Wal95] and constraint programming [JH91, SSW94]. All these paradigms are supported by the programming language Oz [Smo95a, Smo95b] In this paper, we model the time complexity of eager and lazy functional computation in a concurrent calculus. The importance of complexity is three fold: 1. Every implementation oriented model has to reflect ....

Sverker Janson and Seif Haridi. Programming paradigms of the Andorra Kernel Language. In Vijay Saraswat and Kazunori Ueda, editors, Proceedings of the 1991 International Symposium on Logic Programming, pages 167--186, San Diego, California, October 1991.

....for Multi Paradigm Programs goal, the entire process structure is copied. Although this is necessary to compute all solutions, it could be more e#cient to perform a non deterministic step only if a deterministic step in another thread is not possible. This strategy corresponds to stability in AKL [15] and Oz [21] and could be also specified in our framework. 7 Conclusions and Related Work We have presented an operational semantics for functional logic languages based on lazy evaluation with sharing, concurrency, and non determinism implemented by some search strategy. Such a semantics is ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Proc. of ILPS'91, pages 167--183. MIT Press, 1991.

....i.e. yields more than one goal, the entire process structure is copied. Although this is necessary to compute all solutions, it could be more e#cient to perform a non deterministic step only if a deterministic step in another thread is not possible. This strategy corresponds to stability in AKL [14] and Oz [18] and could also be specified in our framework without any problem. We conjecture that is confluent up to variable renaming because the heap can only be extended. If the variable bindings of di#erent threads in the shared heap clash, then this will happen in any scheduling policy ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Proc. 1991 International Logic Programming Symposium, pages 167--183. MIT Press, 1991.

....it yields more than one goal, the entire process structure is copied. Although this is necessary to compute all solutions, it could be more e#cient to perform a non deterministic step only if a deterministic step in another thread is not possible. This strategy corresponds to stability in AKL [16] and Oz [22] and could easily be specified in our framework, too. We conjecture that is confluent (up to variable renaming) for fair search strategies, like breadth first search. The reason is that the heap can only be extended and logical variables can only be bound to one value. If the ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Proc. of the Int'l Logic Programming Symposium (ILPS'91), pages 167--183. MIT Press, 1991.

....And parallelism only in this case naturally stems from running the calculations for each point in parallel. The test program uses a cluster of 400 points as input data. This program has no or parallelism. scanner This is a scanner program to reveal the contents of a bitmap. The program is an AKL [20] benchmark developed at SICS. The problem was described in [10] It reveals the contents of a box (bitmap) The input is the number of dots on each row, column, left diagonal, and right diagonal. The bitmap used in the benchmark is a picture of a star. The program contains both or parallelism ....

Sverker Jansson and Seif Haridi. Programming Paradigms of the Andorra Kernel Language. In Proceedings of the 1991.

....interested only in nitely many of them. A function which 9 For concurrent languages, one could modify the de nition of try such that non deterministic steps lead to a suspension as long as a deterministic step might be enabled by another computation thread. This corresponds to stability in AKL [8] and Oz [15] 9 computes only the rst solution w.r.t. a depth rst search strategy can be simply de ned by once(G) first(all(G) Note that once is a partial function, i.e. it is unde ned if G has no solution. The value computed for the search variable in a search goal can be easily ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Proc. 1991 International Logic Programming Symposium, pp. 167-183. MIT Press, 1991.

....the notion of a store as a constraint on the possible values of variables. Computation progresses by accumulating constraints in the store, and by checking whether the store entails constraints. Recently, several concrete general purpose programming languages have been implemented in this paradigm [JH91, SHW94]. A primitive constraint or token, over a given finite set of variables, is a finitary specification of possibly partial information about the values the variables can take. A typical example of a token is a firstorder formula over some algebraic structure. Tokens come naturally equipped with an ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Logic Programming: Proceedings of the 1991 International Symposium. MIT Press, 1991.

....via concurrent conjunctions of constraints. This separation supports the use of ecient and optimal evaluation strategies for the sequential parts. Similar techniques for the concurrent parts are not available. This is in contrast to other more ne grained concurrent computation models like AKL [19], CCP [27] or Oz [28] Monadic I O: To support real applications, the monadic I O concept of Haskell [29] has been adapted to Curry to perform I O in a declarative manner. In the monadic approach to I O, an interactive program is considered as a function computing a sequence of actions which are ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Proc. 1991 Int. Logic Programming Symposium, pp. 167-183. MIT Press, 1991.

....the set of abducible hypotheses that can be abduced when needed. The second section is a list of constraints which is represented by a set of sublists, each of them representing a constraint on one abducible hypothesis, that is in the head of the sublist. For instance, the sublist: a 1 , c 11 , c 12 , c 1n ] n 0. is equivalent to the integrity constraint: a 1 , c 11 , c 12 , c 1n The tail of the sublist c 11 , c 12 , c 1n represents a conjunction of goals that cannot be true if a 1 is to be abduced. If there is more than one integrity constraint on the same abducible atom, then ....

....is a list of constraints which is represented by a set of sublists, each of them representing a constraint on one abducible hypothesis, that is in the head of the sublist. For instance, the sublist: a 1 , c 11 , c 12 , c 1n ] n 0. is equivalent to the integrity constraint: a 1 , c 11 , c 12 , c 1n The tail of the sublist c 11 , c 12 , c 1n represents a conjunction of goals that cannot be true if a 1 is to be abduced. If there is more than one integrity constraint on the same abducible atom, then more than one sublist would be present in the list of constraints, whose heads are ....

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Janson S. and Haridi S., [1991]: Programming Paradigms of the Andorra Kernel Language, International Symposium in Logic Programming, San Diego, MIT Press, pp. 167 - 183.

....parallel logic programming and concurrent logic programming have been combined into a hybrid model known as the Andorra family of languages combining stream AND parallelism with ORparallelism. Languages that belong to this category include, among others, Andorra I (Santos Costa et al. 1991) AKL (Janson and Haridi 1991) and Pandora (Bahgat 1991) Although it is not shown in this paper, we can implement these languages in Dactl using high level transformation techniques like the ones discussed in Bahgat (1991) where Pandora programs are translated to Parlog equivalent ones. Furthermore, we believe that graph ....

Janson, S. and Haridi, S. (1991) Programming paradigms of the Andorra kernel language, in ISLP91,San Diego, USA, 28 October--1 November, MIT Press, Cambridge, MA, pp. 167--86.

....pre condition for ensuring the correctness and usefulness of many important optimizations. This is exemplified in program parallelization where different notions of independence [9] and the related concept of stability [7] are the basis of models which incorporate Independent And parallelism [3, 5, 9, 12, 20] as in these models the parallel execution of a set of goals in the body of a clause is ensured to be correct and efficient w.r.t. the sequential execution if the goals are proved to be independent. Independence is also the basis of optimizations such as intelligent backtracking [16] and goal ....

....executing the goals. Thus, the conditions will remain valid no matter which computation rule will be later applied in the execution of the goals. Therefore, the results obtained in this section can be directly applied to non deterministic CLP languages with other computation rules, such as AKL [12] or non deterministic concurrent constraint languages in general [18] 5 Solver Independence From the results in previous sections, it may be thought that search space independence is enough for ensuring not only the correctness but also the efficiency of any transformation applied to the search ....

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S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991 International Logic Programming Symposium, pages 167--183. MIT Press, 1991.

....most of these languages have simply eliminated backtracking altogether. However, we feel that backtracking is an integral part of the Prolog control model, and that eliminating it is therefore not an option in our context. A more recent family of languages, including Andorra I [24] and AKL [18] directly addresses the backtracking problem. In Andorra I, choices are suspended until a deterministic path can be taken. AKL allows encapsulated search while, at the same time, communicating deterministic bindings outside such encapsulated operations. While these very interesting proposals solve ....

....is useful. Furthermore, we are interested in nding better solutions to the communication and synchronization among threads. The diculties associated with shared variable based communication have led to the development of other communication and synchronization primitives. One of them is ports [18], used for example by MT SICStus [10] MT SICStus implements a relatively simple design, some aspects of which are derived from Erlang [3] Threads can be spawned (with an initial goal) and killed. They can also send and receive fresh copies of terms, using a single port per thread. This allows ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In ILPS'91, pages 167-183. MIT Press, 1991.

....for example in the store fX 2 f1; 2g; Y 2 f3; 4gg the monotone constraint X in : max(Y ) is entailed without being detected such by Table 4. Only when Y is determined the constraint will be decided entailed (see Section 4. 3) This scheme has been implemented in the AKL system, developed at SICS [7], and preliminary results indicate an efficiency comparable with clp(FD) cc(FD) and CHIP [1] 4.2 Generating entailment checking indexicals In this section we show how to use the entailment detection in Section 4 for checking the entailment conditions of Section 3.1. We adapt Table 2 and Table ....

S. Janson and S. Haridi. Programming paradigms of the Andorra Kernel Language. In Logic Programming: Proceedings of the 1991 International Symposium, MIT Press, 1991.

....The former introduces a committed choice aspect into the language, whereas the latter is a variant of the second approach. All these approaches originated for conventional logic programs, but the ideas lift to constraint logic programs, and there are now several proposals based on these ideas [137, 234, 11, 113, 116]. One potential problem with using guarded rules is that the completeness of the operational semantics with respect to the logical semantics of the program can be lost. This incompleteness was shown to be avoided in ALPS [173] modulo infinitely delayed atoms) but that work was heavily reliant ....

....Smolka [234] discusses a language of guarded rules which extends ALPS and a methodology for extending a predicate definition with new guarded rules such that completeness can 27 be retained, even though execution would involve indeterminate committed choice. The Andorra Kernel Language (AKL) [137] also combines the Andorra principle with guarded rules. There the interest is in providing a language which subsumes the expressive power of CCLP languages and CLP languages. Guarded atoms and, more generally, guarded goals take the form c G where c is a constraint 17 and G is a goal. G is ....

S. Janson & S. Haridi, Programming Paradigms of the Andorra Kernel Language, Proc. International Logic Programming Symposium, 167--183, 1991.

....is included in appendix A and appendix B is an example of its output. 2 Agents Kernel Language AKL AKL is a don t know nondeterministic CCP language created at the Swedish Institute of Computer Science, SICS. A short description of the language is given here but for a complete definition see [JH91], Fra94] or [Jan94] AKL is characterized by notions of communication and synchronization based on constraints. A constraint is a statement that restricts the set of possible values of one or several variables. A set of constraints, regarded as formulas in first order logic, forms a constraint ....

Sverker Janson and Seif Haridi. Programming paradigms of the Andorra Kernel Language. In Logic Programming: Proceedings of the 1991 International Symposium. MIT Press, 1991.

....Model. A mechanism relying on two simple devices (the alt and other attributes) is presented. The construction and application of alt and other is illustrated in the context of the con guration rewrite rules for AKL. 1 Introduction and Motivation The Andorra Kernel Language s (AKL, see [10]) computational model addresses the matter of handling nondeterminism in a di erent way than Prolog, i.e. a computation does not explore the solution space by exploring a derivation tree but rather by deploying a sequence of con gurations (see [9] for an introduction to this subject) AKL con ....

Sverker Janson and Seif Haridi. Programming paradigms of the Andorra kernel language. In Saraswat and Ueda [15], pages 167-186.

....David H. D. Warren and researchers at Bristol concentrated on the Extended Andorra Model with Implicit Control [14] where the goal was to obtain the advantages of the Extended Andorra Model with least e ort from the programmer. Haridi, Janson and researchers at SICS concentrated on the AKL [4], the Andorra Kernel Language, based on the principle that the advantages of the Extended Andorra Model justi ed a new programming paradigm that could subsume both traditional Prolog and the committed choice languages. Research in AKL concentrated on including novel features such as ports [3] ....

Sverker Janson and Seif Haridi. Programming Paradigms of the Andorra Kernel Language. In Logic Programming: Proceedings of the International Logic Programming Symposium, pages 167-186. MIT Press, October 1991.

....systems is native support for concurrent execution. While many systems allow starting a whole subprocess via the operating system interface and this can provide the desired functionality, it is very inecient. A more direct support for concurrency (perhaps along the lines of that present in the AKL [26], Oz [42] and CIAO [24, 18] systems) seems highly desirable and we feel should be provided in all future constraint programming systems. One additional important use of concurrency is in implementing complex, delay based constraint solving algorithms. However, concurrency brings important new ....

....level CIAO is a programming environment o ering support for full standard Prolog, as well as several constraint domains, several control rules, a module and object system, and concurrency, synchronization, and distribution primitives. As opposed to other concurrent constraint languages such as AKL [26] or 5 OZ [42] the language is sequential by default , in the sense that concurrency is annotated explicitly by the user. Optional control rules include for example the determinate rst principle [41] A rich set of assertions is available which the compiler understands and both generates and ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991 International Logic Programming Symposium, pages 167-183. MIT Press, 1991.

....the goals of minimizing the search space and maximizing the parallelism. The original proposal was based in the concept of rewriting and and or boxes. Research then evolved in two directions. One approach was followed by Haridi, Janson and researchers at SICS who concentrated on the AKL [5], the Andorra Kernel Language, based on the principle that the advantages of the Extended Andorra Model justi ed a new programming paradigm that could subsume both traditional Prolog and the committed choice languages. AKL programs were constructed from guarded clauses, where the guard could be ....

Sverker Janson and Seif Haridi. Programming Paradigms of the Andorra Kernel Language. In Logic Programming: Proceedings of the International Logic Programming Symposium, pages 167-186. MIT Press, October 1991.

....a general form of and parallelism. The EAM gives a set of general rewrite rules for logic programs, which can be subject to different control schemes. The EAM was a basis for the Kernel Andorra Prolog (KAP) HJ90] framework which is instantiated in the AKL language, proposed by Janson and Haridi [JH91] In these languages, guards (such as commit guards, cut guards and wait guards) are used to control computation, which may be nondeterministic. Both or parallelism, and and parallelism between non determinate (and determinate) goals can be exploited. Moreover, the search space can be much ....

....and parallelism systems, such as Prolog [HG90] only run independent goals, whose computation should not interfere, in parallel. Andorra I [SCWY91a] exploits and parallelism between goals that are determinate. The latter idea has been generalised in the Extended Model, and in the AKL language[JH91] 5.2 Parallel Implementation of the EAM and AKL Andorra I can only exploit and parallelism between determinate goals. Both the EAm and AKL lift this restriction. AKL and the EAM thus share the property that the computation may be carried out in parallel more naturally than in other parallel ....

Sverker Janson and Seif Haridi. Programming Paradigms of the Andorra Kernel Language. In Logic Programming: Proceedings of the International Logic Programming Symposium, pages 167--186. MIT Press, October 1991.

.... The implementation techniques described in this paper can be used for even those models that have dependent and parallelism, such as Prometheus [SK92] and IDIOM (with recomputation) GY91] They can also be extended to implement the Extended Andorra Model [W90] and its implementations such as AKL [JH90]. Acknowledgements The research presented in this paper has benefited from discussions with Khayri Ali, Roland Carlsson, Tony Beaumont, Ra ed Sindaha, Kish Shen, and David H.D. 19 Warren, all of whom we would like to thank. Special thanks to Kish Shen for discussions and suggestions regarding ....

S. Janson, S. Haridi, "Programming Paradigms of the Andorra Kernel Language. " In Proceedings of the 1990 International Conference on Logic Programming, MIT Press.

....(when the compiler is running inside the system rather than as a stand alone application) As mentioned before, and as an alternative output, most of the capability of the system can also be handled by any Prolog which supports delay declarations and attributed variables. Alternatively, also AKL [JH91] can be used as a target, using the techniques described in [BH95a] Finally, it is possible to obtain the results of each of the intermediate compilation phases. This allows visualizing and affecting the transformation, analysis, parallelization, and optimization processes. Because of the ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991 International Logic Programming Symposium, pages 167--183. MIT Press, 1991.

....via concurrent conjunctions of constraints. This separation supports the use of efficient and optimal evaluation strategies for the sequential parts. Similar techniques for the concurrent parts are not available. This is in contrast to other more fine grained concurrent computation models like AKL [19], CCP [27] or Oz [28] Monadic I O: To support real applications, the monadic I O concept of Haskell [29] has been adapted to Curry to perform I O in a declarative manner. In the monadic approach to I O, an interactive program is considered as a function computing a sequence of actions which are ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Proc. 1991 Int. Logic Programming Symposium, pp. 167--183. MIT Press, 1991.

....on the notion of committed choice. At first, the new model developed as an ad hoc construction, but finally Maher [ Maher, 1987 ] realized that commitment of agents can be captured logically as constraint entailment. A major landmark in the new field of concurrent constraint programming is AKL [ Janson and Haridi, 1991 ] the first implemented concurrent constraint language accommodating search and deep guards. Saraswat s concurrent constraint model [ Saraswat and Rinard, 1990 ] can accommodate object oriented programming along the lines of Shapiro s stream based model for Concurrent Prolog [ Shapiro and ....

S. Janson and S. Haridi. Programming paradigms of the Andorra kernel language. In Logic Programming, Proceedings of the 1991 International Symposium, pages 167--186, 1991.

....in both directions: If C is entailed by the constraint store, the propagator for imply(C; C 0 ) will add C 0 to the store, and if C 0 is inconsistent with the store, the propagator will add :C. Disjunctive propagators can be implemented using deep guards, which were first proposed by Janson and Haridi (1991). They permit very powerful propagation, as every disjunct can be an arbitrary conjunction of constraints. In practice, restricted forms of disjunctive propagators are often replaced by reified constraints, which are more efficient. Selection Constraints. A different approach to disjunction is ....

Janson, S. and S. Haridi. 1991. Programming paradigms of the Andorra Kernel Language. In Saraswat, V. and K. Ueda, editors, Proceedings of the 1991 International Symposium on Logic Programming, pages 167--186, San Diego, California.

....by the receiver. ffl Languages with atomic test and unify allow multiple writers to a single stream. Both approaches suffer efficiency problems as pointed out in [5] Attempts to overcome these insufficiencies include mutual references [9] channels [15] and bags [6] For the ccp language AKL [4], which combines Prolog style searchoriented nondeterministic computation with process oriented committedchoice and ccp, Haridi, Janson and Montelius [5] propose the concept of ports. A port is a connection between a bag of messages which serves as the object identity for the sender and a stream ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In International Logic Programming Symposium, pages 167--186, 1991.

.... the two main approaches currently used in concurrent logic programming, and which are seen traditionally as unrelated: shared variable systems, in which communication among parallel tasks is done through logical variables (e.g. Concurrent Prolog [25] PARLOG [12] GHC [30] Janus [24] AKL [20], Oz [27] etc. and distributed or blackboard systems, in which communication is done through explicit built ins which access shared channels or global data areas (e.g. Multi Prolog [2] Shared Prolog [3] and Prologs incorporating Linda [7] being one of the most popular Linda ....

....encode the determinacy driven synchronization and parallelism of the Andorra I system [23] in terms of our wait primitive and the concurrency operators. We also believe it is quite possible to implement languages with deep guards and or those based on the Extended Andorra Model [31] such as AKL [20]. For example, one of the most characteristic features of deep guard languages is precisely the behavior of the guards, and one of the main complications in implementing such languages is in implementing the binding rules that operate within such guards. If the Herbrand domain is used, the guard ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991 International Logic Programming Symposium, pages 167-- 183. MIT Press, 1991.

....conforms to any of those in our initial assumptions, provided that the data which models the execution can be gathered accurately enough. We plan to modify the simulator in order to support other execution paradigms with more complex task structures (e.g. Andorra I [SCWY90] ACE [GHPC94] AKL [JH91], etc. and to study other scheduling algorithms. Finally, we believe the same approach can be used to study issues other than ideal speedup, such as memory consumption and copying overhead. ....

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991 International Logic Programming Symposium, pages 167--183. MIT Press, 1991.

....a possible non deterministic step in a search goal is suspended if the search goal contains a global variable (since binding this variable outside the search goal might make this step deterministic) or another deterministic step is possible. This corresponds to the stability requirement in AKL [15]. In the context of this paper, the important point is that non deterministic steps are not performed if the search goal has a reference to some global variable. Since we shall model the coordination of distributed activities by partially instantiated global variables, non deterministic steps are ....

....conjunctions of constraints. This separation supports the use of e#cient and optimal evaluation strategies for the sequential parts, where similar techniques for the concurrent parts are not available. This is in contrast to other, more fine grained concurrent computation models like AKL [15], CCP [22] or Oz [25] In this paper, we extend the basic concurrent computation model to support distributed applications where di#erent (external) clients interact. Monadic I O: Since the communication with external programs require some knowledge about performing I O declaratively, we assume ....

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S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Proc. 1991 Int. Logic Programming Symposium, pp. 167--183. MIT Press, 1991.

.... LO As a specification language for our DPS protocols we use LO [3] a declarative concurrent language which amalgamates aspects of concurrent languages based on generative communication, such as CHAM [6] Gamma [5] Linda [8] Swarm [25] as well as of concurrent logic programming languages [9, 10, 15, 19, 32]. LO s logical primitives for agent coordination and communication make it particularly suitable for our purposes; on the other hand, our approach is compatible with other choices of a specification language. The LO programming constructs are rules that define interaction among concurrent agents. ....

Janson, S., Haridi, S.: Programming Paradigms of the Andorra Kernel Language. In: Saraswat, V., Ueda, K. (eds.): Proc. Int. Logic Programming Symp., San Diega, CA, Oct. 1991. Cambridge, MA: MIT Press

....styles and to take the best of both worlds. The Andorra model was proposed by D.H.D. Warren [25] in order to combine Or and And parallelism, and it has now bred a variety of idioms and extensions developed by different research groups, among which Andorra I [6, 5] and the Andorra Kernel Language[11, 12]. The essential idea is to execute determinate goals first and concurrently, delaying the execution of non determinate goals until no determinate goal can proceed. This was inspired by the design of the concurrent language P Prolog[29] where synchronization between goals was based on the concept ....

....section 6 to present and analyze some statistics on the observed performance of the prototype implementation. Finally, in section 7 some conclusions are drawn and our projects for further developments are outlined. 2 Andorra Kernel Language The Andorra Kernel Language (AKL) has been proposed in [12] and is a simplified instance of the framework presented in [11] It is an attempt to fully encompass both Prolog and concurrent logic languages (aka committed choice languages) such as Parlog, FCP or GHC [22] It can be seen in this way as an instance of the Extended Andorra Model where the ....

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Sverker Janson and Seif Haridi. Programming paradigms of the Andorra kernel language. In Saraswat and Ueda [21], pages 167--186.

....compositional, solve combinator Figure 8: History of Oz machines [35] Some of the implementation techniques in the current Mozart system were inspired by KLIC, notably the distributed garbage collection algorithm. An important subsequent development was AKL (Andorra Kernel Language) [56, 55, 57], which added state (in the form of ports) encapsulated search, and an e#cient implementation of deep guards. AKL is the first language that combines the abilities of constraint logic programming and concurrent logic programming. AKL implements encapsulated search using a precursor of computation ....

Sverker Janson and Seif Haridi. Programming paradigms of the Andorra Kernel Language. In Logic Programming, Proceedings of the 1991.

.... is known as a powerful control condition in concurrent execution, which has been first identified by Maher [77] and subsequently used by Saraswat for the cc (concurrent constraint programming) framework [121, 120] Stability has been first conceived by Janson and Haridi in the context of AKL [61, 46, 60]. Oz Light Computation spaces are integrated into the Oz Light programming language. The essential features of Oz Light that make the integration of spaces possible are computing with partial information through logic variables, implicit synchronization of computations, explicit concurrency, and ....

....in S that processes data (that is, constraints) provided by some other concurrent computation. The space S becomes suspended if not all required data is provided. Only after all data is provided, S can become stable. Stability has been first conceived by Janson and Haridi in the context of AKL [61, 46, 60]. Stability naturally generalizes the notion of entailment. Entailment is known as a powerful control condition in concurrent execution, which has been first identified by Maher [77] and subsequently used by Saraswat for the cc (concurrent constraint programming) framework [121, 120] It is ....

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Sverker Janson and Seif Haridi. Programming paradigms of the Andorra kernel language. In Vijay Saraswat and Kazunori Ueda, editors, Logic Programming, Proceedings of the 1991.

....on sequential computers and several parallel machines [8] A number of implementation techniques in the current Distributed Oz system have been borrowed from KLIC, notably the distributed garbage collection algorithm. An important subsequent development was AKL (Andorra Kernel Language) [14], which added explicit state in the form of ports and provided the first synthesis of concurrent and constraint logic programming. AKL encapsulates search by using nested computation spaces. A computation space is a constraint store with its associated goals. Search is done by allowing procedures ....

Sverker Janson and Seif Haridi. Programming paradigms of the Andorra Kernel Language. In International Symposium on Logic Programming, pages 167--183, October 1991.

....This system runs on sequential, parallel, and distributed machines [21] Some of the implementation techniques in the current Mozart system have been borrowed from KLIC, notably the distributed garbage collection algorithm. An important subsequent development was AKL (Andorra Kernel Language) [36, 35, 37], which added explicit state (in the form of ports) encapsulated search, and an ecient implementation of deep guards. AKL provides the rst synthesis of concurrent and constraint logic programming. Search is encapsulated by using nested computation spaces. A com22 putation space is a constraint ....

Sverker Janson and Seif Haridi. Programming paradigms of the Andorra Kernel Language. In International Symposium on Logic Programming, pages 167-183, October 1991.

....This system runs on sequential, parallel, and distributed machines [21] Some of the implementation techniques in the current Mozart system have been borrowed from KLIC, notably the distributed garbage collection algorithm. An important subsequent development was AKL (Andorra Kernel Language) [35, 34, 36], which added explicit state (in the form of ports) and encapsulated search. AKL provides the first synthesis of concurrent and constraint logic programming. Search is encapsulated by using nested computation spaces. A computation space is a constraint store with its associated goals. Search is ....

Sverker Janson and Seif Haridi. Programming paradigms of the Andorra Kernel Language. In International Symposium on Logic Programming, pages 167--183, October 1991.

No context found.

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991.

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S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991 International Logic Programming Symposium, pages 167-183. MIT Press, 1991.

No context found.

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991 International Logic Programming Symposium, pages 167--183. MIT Press, 1991.

No context found.

S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In 1991.

No context found.

S. Janson and S. Haridi. Programming paradigms of the Andorra Kernel Language. Technical Report R91-08, Swedish Institute of Computer Science, 1991.

No context found.

S. Janson and S. Haradi, Programming Paradigms of the Andorra Kernel Language, ILPS 91, San Diego, USA.

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S. Janson and S. Haridi. Programming Paradigms of the Andorra Kernel Language. In Proc. of ILPS'91, pages 167-183. MIT Press, 1991.

No context found.

S. Janson and S. Haradi, Programming Paradigms of the Andorra Kernel Language, ILPS 91, San Diego, USA.

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