M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. ACM Transactions on Programming Languages and Systems, 16(3):649--686, 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....x 6 ) Some solutions to this problem have been proposed in [8, 17] In [8] an additional (and orthogonal) layer of abstraction, the abstraction , is applied to deal with unbounded clause bodies in the abstract semantics. This approach This technique was originally proposed in [9] as state approximation for suspension analysis of concurrent logic programs. provides finitary descriptions for arbitrary large clauses, but makes the analysis less precise. Clause bodies are restricted to contain at most one occurrence of each (open) predicate symbol. In this case, since Pi is ....

....for any set of unit clauses Q 2 AInt , unf ff(Panc ) 2; Q) unf ff(Panc ) 3; Q) The following example shows the applicability of T stable and abstracted semantics in abductive analysis. Example 5. 3 In this example we consider the simpler abstract domain Dep adopted from [9]. Elements in DepV are propositional formulae on V , for any finite nonempty set V Var , with connectives and , ordered by logical implication. It is straightforward to derive Dep by abstractaction of Pos . In the following of this example we assume a kind of merge over all paths MOP abstract ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....In the example, 3 labels fi:x rather than fi:P . The discrepency is due to the substitution semantics of process unfolding. This is tolerated for now treat x and P as the same but will be repaired in the next section with an environment semantics. 24 and Marriott as abstractions [9]. In general, one might need a context free grammar representation of syntax configurations to recover semicompositionality; the precedent here is due to Giannotti and Latella [22] 4.1 Safety and Liveness Properties Safety is stated as before: the a.i. is a simulation of the c.i. t safe T ....

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. In Proc. 8th Int'l. Conf. on Logic Programming, pages 331--345. MIT Press, 1991.

....independence result for systems of equations in general. A particular consequence of our result is that the existence of a floundering does not depend on the computation rule. This last result is closely connected to already known results about suspension analysis for concurrent logic programs ([5, 6, 7]) The framework of these results is abstract interpretation and it is proved that correctness of 2 suspension analysis is independent of the scheduling rule. In particular the approach of [7] is based on abstractions of the SLD tree. 6] shows how suspension analysis can be modified to give ....

....to backtrack. Moreover our characterisation of the floundering independently of the computation rule should be useful to study validation methods : methods to prove that there is no floundering (compare with suspension analysis by abstract interpretation methods for concurrent logic programs ([5, 6, 7]) But this characterisation should also be useful for a kind of declarative diagnosis to find the cause of the appearance of a floundering. A sound implementation of SLDNF resolution (including safeness condition, see [15] needs delaying some negative calls and gives rise to a notion of ....

M. Codish, M. Falaschi, K. Marriott. Suspension analysis for concurrent logic programs, in K. Furukawa ed., Proc. 8th ICLP, pages 331-345, Paris 1991, MIT Press 1991

....compositional complete in [16, 17] Example 11 Consider the Example 10. It is easy to prove that T Pos ff(Panc ) 1 is not T stable, while T Pos ff(Panc ) 2 is T stable. Take for instance Q = fpar(x 1 ; x 2 ) Gamma x 1 x 2 [ trueg then: 3 This technique was originally proposed in [9] as state approximation for suspension analysis of concurrent logic programs. 18 unf A (T Pos ff(Panc ) 1; Q) fanc(x 1 ; x 2 ) Gamma x 1 x 2 [ trueg unf A (T Pos ff(Panc ) 2; Q) anc(x 1 ; x 2 ) Gamma x 1 x 2 [ true anc(x 1 ; x 2 ) Gamma x 1 x 2 [ true ) ....

....of unit clauses Q 2 AInt , unf Pos (T Pos ff(Panc ) 2; Q) unf Pos (T Pos ff(Panc ) 3; Q) The following example shows the applicability of T stable and abstracted semantics in abductive analysis. Example 12 In this example we consider the simpler abstract domain Dep adopted from [9]. Elements in DepV are propositional formulae on V , for any finite nonempty set V Var , with connectives and , ordered by logical implication. It is straightforward to derive Dep by abstract interpretation of Pos. In the following of this example we assume condensing over all solutions i.e. ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....model. Having noted the above, we note there do exist examples in the literature where abstraction on syntax generates small step rule schemes that can be used to generate useful program models. The best known example is the Kleene star abstraction technique of Codish, Falaschi, and Marriott [12, 11], where the size of an unfolded Prolog program is controlled by joining together goal clauses that use the same predicate symbol. A Prolog program is therefore abstracted into a syntax of regular expressions. Schmidt [42] uses a similar regular expression language to abstract the syntax of ....

M. Codish and M. Falaschi and K. Marriott, Suspension analysis for concurrent logic programs. Proc. 8th Int'l. Conf. on Logic Programming, MIT Press, 1991, pp. 331-345.

....the details can get quite complicated: for example, abstracting a sequence of goals into a sequence of abstract goals need not produce a Noetherian abstract domain, and an additional level of abstraction may be necessary to ensure termination. For example, the star abstraction of Codish et al. [6] allows at most one abstract atom with a particular predicate symbol, while Marriott et al. require bounds on the sizes of the multisets describing delayed goals [18] Since our analysis algorithms are really quite straightforward, we felt that trying to formalize them as full blown abstract ....

....track of the set of suspended goals and predict which goals might be awakened at various program points simplifies the implementation significantly and improves its efficiency considerably. Also related is work on analysis of concurrent logic languages, e.g. the deadlock analyses described in [6, 7]. The primary difference between the work of these authors and that described here is that they make no assumptions regarding the scheduler (we assume that goals in a clause body are executed from left to right) and as a result are faced with the formidable problem of accounting for all possible ....

M. Codish, M. Falaschi, and K. Marriott, "Suspension Analysis for Concurrent Logic Programs", Proc. Eighth Int. Conf. on Logic Programming, June 1991, pp. 331--345. MIT Press.

....for several reasons. First of all suspended computations usually correspond to undesired behaviors of the program; their presence is very likely to denote a programming error and, indeed, a lot of research work has been directed to the development of tools for proving a program suspension free [5, 6, 3, 12]. Moreover, a suspension freeness result allows to improve the precision of almost all the other static analyses; strictly speaking, when performing the merge over all path [8] we are allowed to disregard all the computations leading to suspension. Finally, suspension freeness does not behave ....

....x occurs in the constraint, it does not occurs free in it (as 9 x true = true) As an example, let us formalize the constraint system of dependency relations. This domain can be used to propagate interesting properties of program variables (e.g. definiteness) Example 3. 1 [Dependency relations][5] Let V be a finite set of variables and be a property. The set of tokens is defined as D = V ) Theta (V ) frg; the interpretation of a token (X; Y ) 2 D is that if all the variables in Y satisfy property , then all the variables in X satisfy the property too. The entailment j= is ....

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M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....programs We could probably define an execution ordering for Debray s framework to simulate our algorithm. Analyses of concurrent logic languages [19] suffer from the same disadvantages. There are properties that do not rely on execution order, however, and these can be inferred more efficiently [17, 25]. Likewise, Muthukumar and Hermenegildo s sharing analysis [52] detects sharing and groundness to reduce independence tests in independent and parallel implementations, without considering parallel execution (which is not necessary) Fil e and Rossi [29] consider the general analysis of programs ....

M. Codish, M. Falaschi, K. Marriott, Suspension analysis for concurrent logic programs, in Logic Programming: Proceedings of the Eighth International Conference f54g

....been shown that such tools can efficiently be implemented [33, 166] This makes them not only useful but also practical. Moreover, recent work on static analysis of concurrent logic programs indicates that certain aspects of concurrent execution of logic programs are amenable to static analysis [41, 43, 145]. This suggests quite strongly that similar tools for compile time reasoning about program behavior can successfully be developed for concurrent constraint languages, and that such tools can be quite effective in improving the performance of programs. However, it is not obvious that algorithms for ....

.... constraint solving; discovering special forms of constraints, so as to avoid the use of general constraint solvers whenever possible; and proving properties related to concurrent execution, e.g. extending the work done for concurrent logic languages for proving the deadlock freeness of programs [41, 43]. Some work in this regard is reported by Garcia de la Banda and Hermenegildo [59] Second, it is necessary to design abstract domains for such properties, and to develop efficient, i.e. polynomial time (at least in the expected case) algorithms for these computations. Finally, it is necessary to ....

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M. Codish, M. Falaschi, and K. Marriot. Suspension analysis for concurrent logic programs. In Proc. 8th International Conference on Logic Programming. MIT, 1991.

....In this case, any additional unfolding step does not add information with respect to the possible extensions of P . The T stable semantics, denoted F A T , is proved to be compositional complete in [13, 14] Example 6 In this example we consider the simpler abstract domain Dep adopted from [7]. Elements in Dep are propositional formulae on Var with connectives and , ordered by implication. It is straightforward to derive Dep by abstract interpretation of Prop. In the following of this example we assume condensing over all solutions i.e. interpretations can only contain single ....

....restriction reduces the search space for T stability. Moreover, as proved in [6] abstraction for Dep with condensing is compositional correct. Consider the naive reverse routine P rev rev( rev( X Xs] Zs) rev(Xs,Ys) append(Ys, X] Zs) 4 This technique was originally proposed in [7] as state approximation for suspension analysis of concurrent logic programs. where the append procedure is open. A finite compositional abstract semantics can be obtained by iterating unfolding until a T stable sequence is reached. This is obtained after two iterations: F A T (ff(P rev ) ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....and thus derive properties to be used at run time. This holds, for example, for the works on abstract interpretation [128,22] which execute CC programs on an abstract constraint domain with the hope to derive some useful knowledge for program simplification, for those on suspension analysis [20], whose aim is to understand the conditions under which CC program deadlock, and for those on relating CC and CLP languages [15] which try to parallelize CLP programs using CC based techniques or to sequentialize CC programs via an analysis of their inherent concurrency. Languages like AKL [57] ....

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. ACM Transactions on Programming Languages and Systems, 16(3), 1994.

....occurring in the syntactic object , while [ denotes the set of ground instances of . A variable is a variable that appears nowhere else. The symbol denotes a finite sequence of symbols. Identity of syntactic objects is denoted by . We describe the lattice of syntactic equation sets following [7]. We let denote the set of possibly existentially quantified finite sets of equations over terms. We let denote the unsatisfiable equation set, which (logically) implies all other equation sets. Likewise, the empty equation set, denoted , is implied by all elements of . We write if logically ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, , pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....6 ) 9 = Some solutions to this problem have been proposed in [8, 17] In [8] an additional (and orthogonal) layer of abstraction, the abstraction 4 , is applied to deal with unbounded clause bodies in the abstract semantics. This approach 4 This technique was originally proposed in [9] as state approximation for suspension analysis of concurrent logic programs. 20 Abductive Analysis of Modular Logic Programs provides finitary descriptions for arbitrary large clauses, but makes the analysis less precise. Clause bodies are restricted to contain at most one occurrence of each ....

....unit clauses Q 2 AInt , unf Pos (T Pos ff(Panc ) 2; Q) unf Pos (T Pos ff(Panc ) 3; Q) The following example shows the applicability of T stable and abstracted semantics in abductive analysis. Example 5. 3 In this example we consider the simpler abstract domain Dep adopted from [9]. Elements in DepV are propositional formulae on V , for any finite nonempty set V Var , with connectives and , ordered by logical implication. It Abductive Analysis of Modular Logic Programs 21 is straightforward to derive Dep by abstractaction of Pos . In the following of this example we ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....analysis independent way. It is worth noting that problems of sequences approximation were found in areas which are apparently loosely related to the problem of approximating the control. This is the case of the compositional analysis [25, 10, 23] and of the analysis of concurrent logic programs [13, 14]. As we will show in Section 5.3, in several cases the approximation of the simple constraints together with the elimination of multiple constraint occurrences in the sequence, guarantees that the fixpoint is obtained in a finite number of steps. Sufficient conditions for the convergence without ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....equations in a natural way. Identity of syntactic objects is denoted by . is the set of distinct variables occurring in the syntactic object . A variable is a variable that appears nowhere else. The symbol denotes a finite sequence of symbols. We describe the lattice of equation sets following [10]. We let denote the set of possibly existentially quantified finite sets of equations over terms. We let denote the unsatisfiable equation set, which (logically) implies all other equation sets. Likewise, the empty equation set, denoted , is implied by all elements of . We write if logically ....

....of a given set of equations. The main idea behind our method is to abstract the transition system semantics we introduced in Section 3. For this purpose, we follow the topdown approach to abstract interpretation which is based on constructing and examining abstract transition systems as defined in [10]. 1 1 1 1 1 1 1 1 1 n n n n n n n n i n i Definition1. Definition2. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ; fl fl 6 ; 6 6 ; 6 ; 6 2 T [ 62 T [ f g 8 2 T 8 2 T 8 2 ) 8 2 9 2 ) ....

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M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, , pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....with some concurrent logic programming languages. For example, in the following FCP( program, p(X,b) suspends whereas p(X,Y) does not. Work on analysis of suspension in FCP( using abstract interpretation has used abstractions for which callability is closed under instantiation [CCC90] [CFM91]. p(X, Y) true : Y = a true. p(X, Y) X = a : true true. Another unusual feature of Sepia delay statements, also adopted by the Sicstus when meta call is the ability to delay ground calls. Once such a call is delayed it can never be woken since it cannot become more instantiated. The ....

Christopher Codish, Moreno Falaschi, and Kim Marriott. Suspension analysis for concurrent logic programs. In Koichi Furukawa, editor, Proceedings of the Eighth International Conference on Logic Programming, pages 331--345, Paris, June 1991.

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M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

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M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

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M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pages 331- 345. The MIT Press, Cambridge, Mass., 1991.

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M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. of the Eight Int. Conf. on Logic Programming, pages 331-- 345. The MIT Press, 1991.

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M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. of Eighth Int'l Conf. on Logic Programming, pages 331--345. The MIT Press, Cambridge, MA, 1991. 29

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M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. of Eighth Int'l Conf. on Logic Programming, pages 331-345. The MIT Press, Cambridge, MA, 1991.

....[s] denotes the set of ground instances of s. A fresh variable is a variable that appears nowhere else. The symbol e denotes a nite sequence of symbols. Identity of syntactic objects is denoted by . Let Eqn denote the set of possibly existentially quanti ed nite sets of equations over terms [14]. We write E E 0 if E 0 logically implies E. Thus Eqn is a lattice ordered by with bottom element true and top element fail. The elements of Eqn are regarded as (quanti ed) conjunctions of equations and treated modulo logical equivalence. An equation set is solved if it is either fail or ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. of Eighth Int'l Conf. on Logic Programming, pages 331-345. The MIT Press, Cambridge, MA, 1991.

....[s] denotes the set of ground instances of s. A fresh variable is a variable that appears nowhere else. The symbol e denotes a finite sequence of symbols. Identity of syntactic objects is denoted by j. Let Eqn denote the set of possibly existentially quantified finite sets of equations over terms [13]. We write E E 0 if E 0 logically implies E. Thus Eqn is a lattice ordered by with bottom element true and top element fail. The elements of Eqn are regarded as (quantified) conjunctions of equations and treated modulo logical equivalence. An equation set is solved if it is either fail or it ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. of Eighth Int'l Conf. on Logic Programming, pages 331--345. The MIT Press, Cambridge, MA, 1991.

....to deal with unbounded clause bodies in the abstract semantics. Observe, for example, that the abstract unfoldings of the module P sp in Figure 1 introduce arbitrarily long abstract clauses. 7 This problem can be addressed in several ways. In [7] a notion of star abstraction adopted from [9] is applied to limit the length of clause bodies using a domain termed Dep for ground dependency analysis. The basic idea is to collapse the occurrences of calls to a predicate p in a clause body to one canonical call p . While this approach indeed restricts the size of the clauses which can ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. ACM Transactions on Programming Languages and Systems 16(3):649-686, ACM Press, 1994.

....Science, Ben Gurion University of the Negev, PoB 653 Beer Sheba 84105, Israel. codish cs.bgu.ac.il. y Department of Computer Science, K.U. Leuven, Belgium. bimbart cs.kuleuven.ac. be 1 Other analyses involving the domain Prop include various applications for suspension analysis described in [11] and simple type analyses described in [13] A non trivial application for polymorphic type analysis is described in [9] In this paper we focus on groundness analysis as captured by abstract interpretation using the domain Prop. We apply an approach in which a program is analyzed by applying a ....

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. ACM Transactions on Programming Languages and Systems, 16(3):649--686, May 1994.

No context found.

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. In K. Furukawa, editor, Proceedings of the Eighth International Conference on Logic Programming, pages 331--345, Paris, France, 1991. The MIT Press.

....inverse image analysis [14] and Lindstrom s backwards strictness analysis [28] Such methods, as well as demand transformation analysis, can be collected under the general rubric of context analysis. Although abstract interpretation has been applied to concurrent constraint programming (CCP) [4, 3, 5, 11, 27, 36] for many other applications, to our knowledge it has never been used in CCP or logic programming for context analysis. A preliminary presentation of the current research appeared as [15] Organization is as follows. Section 2 reviews the set of Herbrand constraints and the powerdomain ....

....least one a in the second argument. For the output demand that requires a nil terminated list, the input demand expresses the impossibility of obtaining that output. 7. Related work Analysis of concurrent constraint languages: Previous works on analysis of concurrent constraint languages include [4, 3, 5, 11, 27, 36]. 4, 3, 5] study a suspension analysis for a goal (or an agent) in a given program. If the analysis infers that a goal will not suspend, then non suspension is guaranteed for any runtime scheduling rule. The analysis also can determine at compile time a fair scheduling of the goal. As such, it is ....

[Article contains additional citation context not shown here]

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In Koichi Furukawa, editor, Proceedings of the Eighth International Conference on Logic Programming, pages 331--345. The MIT Press, 1991.

....and program from Example 2.1 lead to suspension, as the (standard) transition system shown in Figure 2.2 suspends. The above definition of suspension specifies the global behavior of a system formalizing the concept generally assumed in the context of concurrent (constraint) logic languages (e.g. [3, 4, 6, 24, 26]) However we are often interested in the local behavior of a single process within a system. We introduce the following notion of local suspension, which is similar to the notion of deadlock of an agent in CSP [11] As we have seen from Example 2.4 a notion of fairness is required to formalize ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proceedings Eighth Int'l Conf. on Logic Programming, pages 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....is obtained by simply choosing a description domain and defining operations on the domain. Correctness of the resulting analysis is guaranteed by our construction and by results from abstract interpretation [5] Previous related research includes the works of Codognet et al. 4] and Codish et al. [2, 3], who have investigated the analysis of concurrent logic languages, a particular subclass of the ccp languages. Our work primarily differs from these in the semantic basis of the abstract interpretation. Codognet et al. base their analysis on a complex and operational AND OR tree semantics, while ....

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. of the Eight Int. Conf. on Logic Programming, pages 331-- 345. The MIT Press, 1991.

.... Psi : Example 2 If ASub = Sub) then the relation gt from Example 1 is described by ae hgt(x 1 ; x 2 ) fx 1 7 s(0) x 2 7 0gi; hgt(x 1 ; x 2 ) gt(x 3 ; x 4 ) fx 1 7 s(x 3 ) x 2 7 x 4 gi oe : As an example of a domain of abstract substitutions, consider the domain Dep adopted from [9]: Definition 5.1 [dependency relation] A relation R over a lattice X is additive iff (x R x 0 y R y 0 ) x t y) R (x 0 t y 0 ) A dependency relation R is an additive equivalence relation (reflexive, symmetric and transitive) over (Var) We let Dep denote the complete lattice of ....

.... satisfy the (safety) condition that if mgu A (h a ; 0 i; hhb 1 ; 1 i; hb n ; n ii) i 2 fl S ( i ) 0 i n) and mgu( a 0 ; hb 1 1 ; b n n i) then 2 fl( Example 6 The following is a safe abstract unification function for Dep similar to that introduced in [9]. mgu A D (h a ; 0 i; hhb 1 ; 1 i; hb n ; n ii) n [ i=0 i [ Phi (fxg; vars(t) fi fi x 7 t 2 mgu( a ; b) Psi : where b = hb 1 ; b n i. For instance: mgu A D (hgt(x 0 ; y 0 ) i; hgt(x 00 ; y 00 ) x 00 ; y 00 ;i) x 0 x 00 ; ....

[Article contains additional citation context not shown here]

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pp. 331-- 345. The MIT Press, Cambridge, Mass., 1991.

....(a) if X and Y are ground in a call append(X;Y;Z) then Z is ground in the answer, and (b) if Z is ground in the call then X and Y are ground in the answer. A more general view of the domain Prop interprets propositional formulae with respect to any downwards closed property on terms 3 (see [10]) A simple 3 A property Pon terms is downwards closed if for all terms t; t 0 such that t 0 is more instantiated than t, P(t) P(t 0 ) example is the property list(term) which is true whenever term is a list. Under this interpretation a Prop analysis for the relation append(X;Y;Z) ....

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. ACM TOPLAS. In Press.

....(a) if X and Y are ground in a call append(X ; Y ; Z ) then Z is ground in the answer, and (b) if Z is ground in the call then X and Y are ground in the answer. A more general view of the domain Prop interprets propositional formulae with respect to any downwards closed property on terms 3 (see [10]) A simple 3 A property P on terms is downwards closed if for all terms t ; t 0 such that t 0 is more example is the property list(term) which is true whenever term is a list. Under this interpretation a Prop analysis for the relation append(X ; Y ; Z ) results in the formula X (Y Z ) ....

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. ACM TOPLAS. In Press.

....of which binds X to a ground term if and only if Y and Z are bound to ground terms and (X Y) Z describes substitutions for which any instance grounds either X and Y, or Z to ground terms. Other analyses involving the domain Prop include various applications for suspension analysis described in [12] and simple type analyses described in [14] A non trivial application for polymorphic type analysis is described in [10] In this paper we focus on groundness analysis as captured by abstract interpretation using the domain Prop. We apply an approach in which a program is analyzed by applying a ....

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. ACM Transactions on Programming Languages and Systems, 16(3):649-- 686, May 1994.

No context found.

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. In K. Furukawa, editor, Proceedings of the Eighth International Conference on Logic Programming, pages 331--345, Paris, France, 1991. The MIT Press.

....O 2 ) 8 2 Theta: covers (O 1 ; O 2 ) The notion of covering provides an alternative definition for the groundness predicate: ground Theta (t) covers Theta ( t) The notion of covering is easily generalized to express implications between other types of properties. For example, in [12], various covering properties are applied to determine nonsuspension for concurrent logic programs. The notion of covering is the basis of the Prop domain [4, 11, 30, 34, 43] where a basic relation covers (hX 1 ; Xn i; Y ) is expressed as a propositional formula X 1 : Xn Y . ....

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. ACM Trans. Prog. Lang. Syst., 16(3):649--686, May 1994.

....ensure termination of analyses. Section 7 discusses modifications of the suspension analyses to give analyses for deadlock and floundering. Section 8 describes related 4 1 M. Codish, M. Falaschi, K. Marriott work and finally, Section 9 concludes. A preliminary version of this paper appeared in [4]. 2. EXAMPLE Concurrent logic programs consist of finite sets of guarded clauses which specify rules for reducing states. The basic notions of concurrency processes, communication, synchronization and non determinism are realized in concurrent logic languages by viewing each atom in a ....

M. Codish, M. Falaschi, and K. Marriott. Suspension analysis for concurrent logic programs. In Furukawa [12], pages 331--345.

.... 9 : Example 2 If ASub = Sub) then the relation gt from Example 1 is described by ae hgt(x 1 ; x 2 ) fx 1 7 s(0) x 2 7 0gi; hgt(x 1 ; x 2 ) gt(x 3 ; x 4 ) fx 1 7 s(x 3 ) x 2 7 x 4 gi oe : As an example of a domain of abstract substitutions, consider the domain Dep adopted from [9]: Definition 5.1 [dependency relation] A relation R over a lattice X is additive iff (x R x 0 y R y 0 ) x t y) R (x 0 t y 0 ) A dependency relation R is an additive equivalence relation (reflexive, symmetric and transitive) over (Var) We let Dep denote the complete lattice of ....

.... satisfy the (safety) condition that if mgu A (h a ; 0 i; hhb 1 ; 1 i; hb n ; n ii) i 2 fl S ( i ) 0 i n) and mgu( a 0 ; hb 1 1 ; b n n i) then 2 fl( Example 6 The following is a safe abstract unification function for Dep similar to that introduced in [9]. mgu A D (h a ; 0 i; hhb 1 ; 1 i; hb n ; n ii) n [ i=0 i [ 8 (fxg; vars(t) fi fi x 7 t 2 mgu( a ; b) 9 : where b = hb 1 ; b n i. For instance: mgu A D (hgt(x 0 ; y 0 ) i; hgt(x 00 ; y 00 ) x 00 ; y 00 ;i) x 0 x 00 ; y 0 ....

[Article contains additional citation context not shown here]

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. In K. Furukawa, editor, Proc. Eighth Int'l Conf. on Logic Programming, pp. 331-- 345. The MIT Press, Cambridge, Mass., 1991.

No context found.

M. Codish, M. Falaschi, and K. Marriott. Suspension Analysis for Concurrent Logic Programs. ACM Transactions on Programming Languages and Systems, 16(3):649--686, 1994.

No context found.

M. Codish, M. Falaschi, K. Marriott, Suspension analysis for concurrent logic programs, 8th Internat. Conf. on Logic Programming (ICLP-91), Paris (France), June 1991.

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