Vijay A. Saraswat, `Concurrent constraint programming languages', Ph.D. Thesis, Carnegie-Mellon University, Computer Science Department, January 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Other researchers have combined logical and constraint reasoning, usually in the context of programming languages. clpr may be thought of as an integration of Prolog and linear programming, and this work introduced the notion of incremental Simplex [ Ja#ar et al. 1992 ] Saraswat s thesis [ Saraswat, 1989 ] formulates a family of programming languages which operate through the incremental construction of a constraint framework. chip [ Van Hentenryck, 1989 ] augments logic programming with the tools to e#ciently solve constraint satisfaction problems (e.g. consistency checking) but deals only ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, Computer Science Department, January 1989.

....Other researchers have combined logical and constraint reasoning, usually in the context of programming languages. clpr may be thought of as an integration of Prolog and linear programming, and this work introduced the notion of incremental Simplex [ Ja#ar et al. 1992 ] Saraswat s thesis [ Saraswat, 1989 ] formulates a family of programming languages which operate through the incremental construction of a constraint framework. A variety of recent systems have addressed the issue of integrating metric reasoning into planning. ILPPLAN [ Kautz and Walser, 1999 ] solves planning problems that have ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, Computer Science Department, January 1989.

....are presented in sections 5 and 6 respectively. 2 Concurrent Constraint Logic Programming The real time extensions to be presented are founded in the theory of concurrent constraint logic programming (cclp) to which a brief introduction is now given. The interested reader is referred to [13, 14] for further information. The architecture of a cclp language, shown in Figure 1, consists of an executing program communicating with a central store. A program is composed of a number of concurrently executing agents, 1 each of which communicates independently with the store via ask and tell ....

....to the store and ensuring correct computation regardless of the time constraints take to migrate through the repository. The will be used to represent eventual tells as shown below. V c) 3 The motivation of eventual tell is largely distributed systems. The interested reader is referred to [13, 14] for details. 153 3 Incorporation of Temporal Constraints 3.1 Introducing the Notion of Time The proposed structure of the real time cclp language (rtcclp) is given in Figure 3. The reader will note the similarity between the rtcclp architecture and that of the eventual tell. Ask Program ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, 1989.

....disorderly. Note that CLP is orderly since adding required constraints to an existing set of required constraints will either narrow or leave the same the set of valuations that satisfy those constraints. This orderliness property is similar to the stability of rejection property discussed in [12]. Proposition. Let D be a nontrivial domain. Then any comparator that respects the hierarchy is disorderly. Proof. Let H = fdefault X = ag, and let J = fprefer X = bg, where a and b are two distinct elements in D. Let C be a comparator that respects the hierarchy. Then S fHg (C) consists of the ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, CarnegieMellon University, Computer Science Department, January 1989. 13

....X 5 is neither entailed or disentailed. If an agent would ask this constraint store if X 5 then the constraint solver could not answer until further information was given by some other agent. Basic statements, such as constraints, calls, composition, and hiding, are as in other CCP languages [Sar93] (see Figure 1) Choice statements are sequences of clauses. The first statement of a clause is the guard and the second the body. The operator is one of , or j , and to these correspond conditional choice, nondeterminate choice, and committed choice statements, respectively. The guards of ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. MIT Press, 1993.

....Execution Model : 19 3.1 Blocks World : 97 4. 1 Implementation Method : 107 x Chapter 1 Introduction In his dissertation on concurrent constraint programming languages [58] Saraswat developed and formalized the idea of computing with partial information by means of transforming the von Neumann concept of store as value to one of store as constraint. Rather than the store containing totalities, which may arbitrarily change, the notion of store as constraint yields a ....

....universe) As a prerequisite to this, we will first cover the formal background to concurrent constraint languages and discuss methods of disjunctive and hypothetical reasoning already investigated in logic languages. CHAPTER 1. INTRODUCTION 4 1. 1 Background Concurrent constraint languages [58, 32, 61, 60, 62] grew out of a formalization of concurrent logic languages 2 [46, 65, 72, 66] The concept of programming with constraints is taken from the work on constraint logic programming [30, 31, 39, 29, 12, 13, 22] which itself is a generalization of Prolog [36, 9, 69] 1.1.1 Terminology For the sake ....

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Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, Pittsburg, 1989.

.... algorithm takes the state of the system from one store (satisfying some pre condition) to another store (satisfying a post condition) In contrast, the store in a constraint system is defined as a constraint which defines a set of points or valuations in the n dimensional space for that system [Sar89] Evaluation of a constraint system leads to determination of the specific points in the state space where all the constraints in the system are satisfied. A new constraint can be added to a constraint system if the resultant store is consistent, that is, it permits at least one valuation ....

....[Sar89] Evaluation of a constraint system leads to determination of the specific points in the state space where all the constraints in the system are satisfied. A new constraint can be added to a constraint system if the resultant store is consistent, that is, it permits at least one valuation [Sar89] The resultant store is defined by the intersection of the sets of valuations corresponding to the old store and the added constraint. Hence, it is not possible to change the value of any variable in a constraint system. However, it is possible to refine the set of values a variable can assume ....

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Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie Mellon, School of Computer Science, Pittsburgh, 1989.

....the question of whether the theory is Henkin is important, and that the notation and proof theory of substructural logics can help in these characterizations. The definition of a reliable satisfiability function is closely related to Scott s definition of an information system [Sco82] Saraswat [Sar89] uses information systems to describe the domains of constraint systems. However, neither the space of satisfiability functions, nor the space of information systems (under a reasonable mapping from one notion to the other) are proper subsets of the other. Hohfeld and Smolka [HS88] and Fruhwirth ....

....problems for logic programming theory which have not been adequately answered yet. A framework which characterizes the failure of constraint queries as well as their success would be desirable. ffl Ask constraints. I have considered here only constraints that would be described by Saraswat [Sar89] as tell constraints. I would also like to characterize ask constraints; this may involve allowing some description of implication in characterizing proof systems. Thanks to Andreas Podelski for interesting discussions on this point. ffl Moving toward a standard description language. It ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, Department of Computer Science, Pittsburgh, January 1989.

....the soft constraints. We would then minimize the value of an expression that was the weighted sum of the errors of the constraints at the strongest non required level (using the minimize operator) then the weighted sum of the errors of the next level, and so forth. The cc family of languages [58, 59] generalizes the CLP scheme to include such features as concurrency, atomic tell, and blocking ask; up to this point we haven t dealt with these additional issues in the HCLP framework. Maher and Stuckey [42] give a definition of constraint hierarchies similar to the one in this paper. In their ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, CarnegieMellon University, Computer Science Department, January 1989.

....interesting conceptually, has little hope of generating programs which will be of competitive efficiency with programs compiled to procedural representations of the same computations. There has also been considerable work in the logic programming community in concurrent constraint programming [15]. Our programming model is significantly different from the ask and tell framework of CCP languages. We adopt the store as valuation concept as in the imperative programming paradigm as opposed to the store as constraint [16] notion in concurrent constraint programming. There has been considerable ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie Mellon, Pittsburgh, 1989. School of Computer Science.

....Versions of Kaleidoscope 2 Background A number of experimental programming languages include support for constraints. Much of the activity in this area has been based in logic programming, and includes the CLP and cc (concurrent constraint) languages [Cohen 90, Colmerauer 90, Jaffar Lassez 87, Saraswat 89, Van Hentenryck 89, Van Hentenryck et al. 92, Wilson Borning 93] Other constraint languages include Steele s language [Steele Jr. 80] Bertrand [Leler 87] and Siri [Horn 92a, Horn 92b] Of these, Siri, another constraint imperative language, is the closest to Kaleidoscope. For discussions ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, Computer Science Department, January 1989.

....Other researchers have combined logical and constraint reasoning, usually in the context of programming languages. clpr may be thought of as an integration of Prolog and linear programming, and this work introduced the notion of incremental Simplex [ Jaffar et al. 1992 ] Saraswat s thesis [ Saraswat, 1989 ] formulates a family of programming languages which operate through the incremental construction of a constraint framework. chip [ Van Hentenryck, 1989 ] augments logic programming with the tools to efficiently solve constraint satisfaction problems (e.g. consistency checking) but deals only ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, Computer Science Department, January 1989.

.... constraints, including Bertrand [30] Kaleidoscope [14, 18] Siri [23, 24] as well as a number of languages integrating constraints with logic programming including CAL [42] CHIP [9, 46] CLP(R) 27, 28] CLP(6 ) 48] HCLP(R) 6, 49] Prolog III [8] and the cc (concurrent constraint) languages [41, 40]. 2.1 Refinement versus Perturbation We can roughly classify constraint based languages and systems as using one of two approaches: the refinement model or the perturbation model. In both cases constraints restrict the values that variables may take on. In the refinement model, variables are ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, CarnegieMellon University, Computer Science Department, January 1989.

....26] Two generalizations of the CLP scheme are CLP [13] which generalizes CLP by allowing predicates to be defined dynamically as first class objects, and HCLP [2, 28] which generalizes CLP by including constraint hierarchies rather than just required constraints. Finally, in the cc languages [23, 24] the conventional store of a Von Neumann computer is replaced by one that holds constraints. Concurrently executing agents communicate by asking and telling constraints to this store. 6 Future Work We are currently redesigning and simplifying our language to produce Kaleidoscope 91. In addition, ....

Vijay Anand Saraswat. Concurrent Constraint Programming Languages. PhD thesis, CarnegieMellon University, Computer Science Department, January 1989.

....guards. However, for the body of a clause to be promoted, it is not necessary for all guard computations to cease. Instead what is required for A i together with a solution s of G i to be promoted is that s is quiet in essentially the sense of the concept of entailment or validation of [Ma] [Sa], and that the guard computations for G j have failed for all j i. Upon promotion of A i together with s, or, perhaps more efficiently, whenever a solution of G i is found) all guard computations associated with G j for j i are killed, as are any remaining computations associated with G ....

Vijay Saraswat, Concurrent Constraint Programming Languages, PhD dissertation, Carnegie-Mellon University, 1989.

....languages can be extended for real time and second, to allow schedulability of the language by assigning urgencies to all processes of a program. 1. 1 Concurrent Constraint Logic Programming The work presented here is centered around the notion of concurrent constraint logic programming(cclp) [9]. We now give a brief introduction to the relevant issues of cclp. The architecture of a cclp language, shown in Figure 1, consists of an executing program communicating with a central store. A program is composed of a number of agents, 1 each of which communicates 1 Here we use the term agent ....

....and finish times are the two parts of a temporal constraint. An infinite or zero specification of finish or start time respectively is used to indicate a non specification. For example an agent 3 The motivation of eventual tell is largely distributed systems. The interested reader is referred to [9] for details. that wishes to be delayed for a period of Delay but not have a definite finish time could post a constraint such as given in equation 1 (where T c is the current time, t s the start time and t f is the agents desired finish time) An agent with a specific deadline by which ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, 1989.

....Consul [2] is a parallel constraint language that was developed as a vehicle to experiment with implicitly parallel, constraint based programming. The ThingLab and the Kaleidoscope projects [6, 5, 23] came from the University of Washington. Concurrent constraint programming (CCP) languages [26] established the foundations of concurrent computation with constraints. Consul: This work resembles our work in that the goal is to extract parallelism from constraints [2] But the approach is different in that local propagation is used to find satisfying values for the system of constraints. ....

....[17, 9] defines a general scheme for constraint logic programming. Different implementations of the scheme are described in languages like Prolog III, CLP(R) and CHIP [12, 18, 13, 16, 22] Vijay Saraswat described a family of concurrent constraint logic programming languages,the cc languages [26]. The logic and constraint portions are explicitly separated with the constraint part acting as an active data store for the logic half. The logic communicates with the constraint part only through constraints either by a tell operation (a new constraint is added to the store) or an ask ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie Mellon, Pittsburgh, 1989. School of Computer Science.

....Thus constraints can be combined using propositional connectives to model cardinality and disjunction simply by flattening to systems of reified constraints and arithmetic constraints over their 0 1 variables. Reification subsumes several frequently used operations such as blocking implication [20] and the cardinality operator [23] These 0 1 variables may be used in other constraints, thus complex constraints can often be decomposed into a system of many reified, simple constraints. A crucial operation in reification is entailment detection. It has been shown that indexicals can be used ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, January 1990.

.... In contrast, in the refinement model of constraints, the set of possible values for each variable is refined during the execution of the program (but never altered in other ways) This model is more declarative, and is invariably used in the constraint systems rooted in logic programming (e.g. [6, 11, 21, 35]) We therefore set as a subgoal the use of a refinement model in the integrated language. 6. Finally, it should be reasonably efficient. 1.2 Non Goals We also suggest a number of non goals for such an integration: 1. Although it should be reasonably efficient, it need not be 100 as efficient ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, Computer Science Department, January 1989.

....transforms constraints to a compilable language rather than to an interpretive execution environment as in many constraint systems, but is not concerned with extraction of parallel structures. Vijay Saraswat described a family of concurrent constraint logic programming languages, the cc languages [18]. The logic and constraint portions are explicitly separated with the constraint part acting as an active data store for the logic portion of the program. Oz is a concurrent programming language based on an extension of the basic concurrent constraint model provided in [18] The performance ....

....the cc languages [18] The logic and constraint portions are explicitly separated with the constraint part acting as an active data store for the logic portion of the program. Oz is a concurrent programming language based on an extension of the basic concurrent constraint model provided in [18]. The performance reported for the system is only comparable with commercial Prolog and Lisp systems [15] Parallel logic programming [5, 9, 13] is another area of related work. PCN [5] and Strand [9] are two parallel programming representations with a strong component of logic specification. ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie Mellon, Pittsburgh, 1989. School of Computer Science.

.... Franz en Seif Haridi Sverker Janson Swedish Institute of Computer Science y March 20, 1992 1 Introduction The Andorra Kernel Language (AKL) is a general combination of search oriented nondeterministic languages, such as Prolog, and the process oriented committedchoice languages, such as GHC [10, 8, 9]. For an introduction to the language from this perspective, see [7] For an extensive formal treatment, see [4] Although the Prolog programming paradigm is provided, AKL does not provide the exact operational semantics of the Prolog cut, nor does it provide Prolog style side effects. Automatic ....

....commit and sequential conjunction. We have earlier developed a formal computation model derived from these rules for the language framework Kernel Andorra Prolog (KAP) 6] AKL is a refined instance of KAP. For more details on this relation see [7] The work of Vijay Saraswat was very influential [9], in particular for the notions of constraints and constraint operations. AKL is being implemented and the results so far are promising. The current implementation covers everything described in this paper, and more. In our AKL environment, we use public domain code originally written in Prolog ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. PhD thesis, Carnegie-Mellon University, January 1990.

....Thus, it is not unreasonable to describe DRT as a form of constraint programming for discourse analysis. The same description applies to an extension of DRT presented below, 1 the purpose of which is best described by illustration. Notice that the variable for 1 Readers familiar with Saraswat [14], however, should be cautioned that in the present paper, i) quantifiers are employed to introduce variables on which constraints can then be imposed, and (ii) parallel computations arise when a process spawns multiple processes, which then proceed in a conjunctive fashion, with identically ....

....(i) quantifiers are employed to introduce variables on which constraints can then be imposed, and (ii) parallel computations arise when a process spawns multiple processes, which then proceed in a conjunctive fashion, with identically initialized but separate stores. This contrasts with Saraswat [14], where an existential quantifier is used to hide a variable, which, otherwise, might be shared by processes running in parallel. The concept of locality or scope analyzed in Saraswat [14] should not be confused with what is called force below. No claim is (of course) made here that (i) and ....

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Vijay A. Saraswat. Concurrent Constraint Programming Languages. Dissertation, Carnegie-Mellon University, 1989, Published by the MIT Press.

.... 1) consists of an executing program with a central store(memory map) A program is composed of a number of processes in the constraint logic programming scheme(agents) each of which communicates independently with the store via ask and tell operations (roughly corresponding to read and write) 7][9]. The ask and tell operations read and post constraints(not data values) Those constraints remain in the store, after sending, during the time the computation takes. Constraints are added to the existing constraints of a variable in a conjunctive fashion. A computation fails if there exists a ....

Vijay A. Saraswat. Concurrent Constraint Programming Languages. (Used in [7. SAVO]).

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Vijay A. Saraswat, `Concurrent constraint programming languages', Ph.D. Thesis, Carnegie-Mellon University, Computer Science Department, January 1989.

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Vijay A. Saraswat, Concurrent Constraint Programming Languages , PhD thesis, Carnegie-Mellon University, January 1989.

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