L. Monteiro and A. Porto. Contextual logic programming. In Proc. of ICLP'89, pages 284-299. MIT Press, Cambridge, MA, 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....operator r behaves identically on and . From this, it follows that P and P c have the same classes of proper models, which implies the theorem. 2 5.2 Proof Rules In this section we develop a goal directed sequent style proof system for ORLog programs. We adopt this style along the lines of [21, 22]. In Figure 5 below, we present four inference rules which de ne the properties of the proof predicate . We use the notation P c G to represent the fact that the goal G is derivable from the closed program P c with a substitution , i.e. P c G . Following [22] the structure of the ....

....along the lines of [21, 22] In Figure 5 below, we present four inference rules which de ne the properties of the proof predicate . We use the notation P c G to represent the fact that the goal G is derivable from the closed program P c with a substitution , i.e. P c G . Following [22], the structure of the proof rules are as shown below where we read them from bottom up. Note that the application of a proof rule is contingent upon the satisfaction of the conditions speci ed at the right hand side of each rule. The inference gures or proof rules for ORLog are shown in Figures ....

L. Monteiro and A. Porto. Contextual Logic Programming. In 6th ALP Intl. Conf. on Logic Programming, 1989.

....ways of inheritance [19] In all these cases, the compositions of modules introduce an ordering among programs, often by stacks. Statically, a program is a set of modules. Dynamically, goals are solved in the changing sets of modules (contexts) Contextual programming is formally described in [20]. A context is an ordered set of modules which can change during the process of proving a formula. Contrary to standard logic programming, where predicate definitions are given statically and cannot be changed, predicates definitions are in contextual programming no more static and depend on the ....

L. Monteiro, A. Porto. Contextual Logic Programming. In Proc. 6th Int. Conf. and Symposium on Logic Programming. G. Levi, M. Martelli (Eds.), The MIT Press, Cambridge (USA), pages 1-26. 1989.

....The notion of module has mostly a syntactic flavor, while a fundamental requirement should be the capability to organize knowledge on the basis of coherent (structured) semantic domains. The notion of open, structured theory seems to better match this requirement. Contextual logic programming [4] allows to define static theories (units) which can be dynamically composed into structured theories (contexts) us ing context extension operators. Thus, structured software components can be dynamically built up from open theories used as shared and reusable basic blocks. A contextual ....

L. Monteiro and A. Porto. Contextual Logic Programming. in G. Levi and M. Martelli, editors, Proceedings of the Sixth International Conference on Logic Programming. The MiT Press, 1990.

.... considering concurrency ( 8, 57] ore not explicitly considered due to o rother peculior foshion in dotobose field where concurrency is omong tronsoctions ond the moin purpose of o concurrent tronsoction model is to keep integrity of doto [58] Along this woy we find Contextuol Logic Progromming [51, 52] ond messoges used os o woy to ochieve o logicol reinterpretorion for some of the distinguishing feotures of the object oriented progromming porodigm [49, 27] A prototypicol system supporting knowledge portitioned in theories ond in which gool refutotion con move from one theory to onother ....

L. Monteiro and A. Porto. Contextual Logic Programming. In G. Levi and M. Martelli, editors, Proc. Six'th lnt'l Conf. on Logic Programming. The MIT Press, Cambridge, Mass., 1989.

.... a sequential computation (although the use of lambda terms instead of first order terms, and the fact that clauses may be dynamically loaded in the proof, make things more complex than in the classical case) On the other hand, in a parallel environment, it has been shown in [3, 4, 6] and also in [27, 14, 11], that the formalism of multi headed formulae (e.g. methods here) is better suited, especially for synchronization purposes. Contextual Horn clauses [27] or the logical objects of [14] or Shared Prolog [11] basically correspond to the fragment of LinLog 4 In fact, further refinements would be ....

....things more complex than in the classical case) On the other hand, in a parallel environment, it has been shown in [3, 4, 6] and also in [27, 14, 11] that the formalism of multi headed formulae (e.g. methods here) is better suited, especially for synchronization purposes. Contextual Horn clauses [27], or the logical objects of [14] or Shared Prolog [11] basically correspond to the fragment of LinLog 4 In fact, further refinements would be needed to account for the fact that Progression can only be triggered when the context C is flat, and also for the fact that the head of a method may ....

L. Monteiro and A. Porto. Contextual logic programming. In Proc. of the 6th International Logic Programming Conference, Lisboa, Portugal, 1989.

....the family of Actor languages (see for instance [1] as we have shown in [5] One of the main aims of LO is that of providing a more structured notion of goal formula, suitable to represent structured objects with changeable state. In this sense, our effort is complementary with efforts such as [14, 24, 23, 26], which introduce a more structured notion of logic program, suitable for modular logic programming. Recent developments in this direction [18] also make use of Linear Logic operators to implement more refined notions of control. Acknowledgement We are indebted to Francois Bry, Gerard Comyn, ....

L. Monteiro and A. Porto. Contextual logic programming. In Proc. of the 6th International Logic Programming Conference, Lisboa, Portugal, 1989.

....but rather one has to address objects using explicit object identifiers. One of the main aims of LO is that of providing a more structured notion of goal formula, suitable to represent structured objects with changeable state. In this sense, our effort is complementary with efforts such as [9, 18, 17, 20], which introduce a more structured notion of logic program, suitable for modular logic programming. It would be particularly interesting to compare our approach with recent developments of this line of research towards objectoriented programming [13] Finally, we would like to compare it in ....

L. Monteiro and A. Porto. Contextual logic programming. In Proc. of the 6th International Logic Programming Conference, Lisboa, Portugal, 1989.

....motivations, the two approaches are actually strictly related. In fact, the composition mechanisms are conceptually the same; the difference is that they act as meta linguistic operators in the former and a linguistic operators on the latter (see [9] for a fuller discussion on this issue) In [23] Monteiro and Porto proposed Contextual Logic Programming (CxLP) as a modular logic programming language based on a new type of implication goal, called extension goal and denoted by D AE G. Operationally, D AE G is provable in the program P if (the goal) G can be proved in (the set of clauses) D ....

L. Monteiro and A. Porto. Contextual Logic Programming. In G. Levi snd M. Martelli, editors, Proc. of the 6th Int.l Conference on Logic Programming, pages 284-299. The MIT Press, 1989.

....may depend on the context in which they are used. Similarly, the mechanism for supplying security in abstract datatypes is described as a runtime check ; it cannot, in general, be done at compile time. For proposals of more static notions of modules and abstract datatypes for logic programs, see [4, 15, 20, 21]. 2. The logic programming language L Consider a logic that contains constants and variables for individuals, functions, and predicates. Let A; D;G be syntactic variables that range over the following classes of formulas. A : atomic formula 2. The logic programming language L 14 May 1997 D : ....

L. Monteiro and A. Porto, Contextual Logic Programming, Proceedings of the Sixth International Logic Programming Conference, Lisbon Portugal, June 1989.

....parameter H of the program to simulate di erent conditions. Indeed the same programming technique can be also used to plan the travel by considering the current weather and trac situation, if H is used to link an updated database. 4. 3 Contextual logic programming Monteiro and Porto introduced in [8] the paradigm of contextual logic programming. The basic idea is to partition a logic program into a collection of named programs (units) which are viewed as sets of context dependent de nitions of predicates. Programs may be dynamically combined together to form contexts, which denote ....

....g The derivation of an atomic formula may be described by the following two rules: ii) a b 2 ground(u) uc b uc a (iii) name(a) 62 defs(u) c a uc a 11 where rule (iii) de nes the overriding mechanism of contextual logic programming. For instance, consider the following units [8]: Books: Authors: Wrote(Plato,Republic) Author(x) Wrote(x,y) Wrote(Homer,Iliad) Author(x) Authors Author(x) The query Books Author(Plato) generates the following refutation: Books Author(Plato) Books Authors Author(Plato) Authors Books Author(Plato) Authors Books ....

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L. Monteiro and A. Porto. Contextual logic programming. In G. Levi and M. Martelli, editors, Proceedings Sixth International Conference on Logic Programming, pages 284-302. The MIT Press, 1989.

....inheritance has been treated successfully by introducing principles from modular logic programming [Bug92, BLM94, AKM97] Modularity is a special form of program composition that allows incremental development and code reusability. One of its forms in logic programming is supplied by units [MP89] Units consist of named pieces of code and each unit has its own name space. Encapsulation in the logic programming framework has been treated in a variety of works. In the following, we briefly present some representative approaches. F Logic [KLW94] treats encapsulation as type correctness ....

L. Monteiro and A. Porto. Contextual logic programming. In 6th International Conference in Logic Programming, pages 284--299, 1989.

....composition. This approach, first introduced in [O K85] have been followed by various researchers [Bro93, BMPT90, MP88] In the second approach, the language of Horn clauses has been extended to allow implication goals in the bodies. The pioneer work is presented in [Mil86] and the work in [MP89] is an eminent one. In [Bug92] an attempt was made to combine the two approaches, proposing SelfLog, a framework where both paradigms co exist. The paper is organized as follows. In Section 2, some information concerning the background of the framework is presented. In Sections 3 and 4, two ....

....a modular logic programming language that captures the notion of non monotonic inheritance, where class hierarchies can be modeled by algebraic composition and are combined with inter unit communication by message goals. The basic program block in SelfLog is the unit. Units, first introduced in [MP89], stand for named pieces of program which determine environments. A SelfLog unit is composed of extended Horn clauses. The difference with pure Horn clauses is that in the body of such a clause we may have a goal of the form u : g (message goal) This means that the goal g has to be evaluated in ....

L. Monteiro and A. Porto. Contextual logic programming. In 6th International Conference in Logic Programming, pages 284--299, 1989.

....to decompose a single logic theory into a collection of knowledge bases, it is up to the programmer to drive the control of the deductive process in order to achieve the proof of a theorem from the program intended as a whole. A similar attitude is required in the contextual programming model [14], which however exploits modularity by starting from the idea of knowledge base extension rather than knowledge base switching. The main advantage of the contextual approach over the traditional modular one is to introduce in sequential logic programming software engineering concepts and ....

L. MONTEIRO, A. PORTO, Contextual Logic Programming, Proc. 6th ICLP, Lisbon, Portugal, The MIT Press, 1989.

....paradigm. These proposals cover a wide space, ranging from the conventional notion of scope rule and blockbased programming [1] to the integration into the logic framework of Object Oriented ideas [2,3] 2 In this wide research space, the concept of contextual programming first proposed in [4], later refined in [5] and implemented in [6] does assume a rather intermediate position. In fact, contextual languages do not force a specific program structuring model: rather, since the notion of context is intrinsically related to the notion of scope and binding environment, contextual ....

L. Monteiro, A. Porto, Contextual Logic Programming, Proceedings of the Sixth International Conference of Logic Programming, The MIT Press, Lisboa, Portugal (June 1989).

....(see e.g. Delta Prolog problems in [11] are avoided. All blackboards created by the reduction of an application inherit the program of the application. This explains why the tellbb does not specify any program. Refinements could include the definition of the programs as sets of modules (as in [10]) from which tellbb could extract those which would be told on the blackboard and used by processes running on it. However, this is not essential for the purpose of this paper and is thus left for future work. The 2 Log framework distinguishes two kinds of processes. Processes that are created ....

L. Monteiro and A. Porto. Contextual Logic Programming. In G. Levi and M. Martelli, editors, Proc. 6 th Int. Conf. on Logic Programming, pages 284--302, Lisboa, 1989. The MIT Press.

....solve(C in S, G) undefined(G, C) solve(S, G) For a component C the Prolog operator in acts as the constructor of the context provided by the state of the game S. The definition above is an instance of the metalogic definition described in [2] to support contextual logic programming [12]. The undefined 2 predicate is the context overriding mechanism expressed as a membership test on the names of predicates describing the state of the game. We can continue the formulation of the umpire by defining how moves are checked. In forward mode, a move made is checked as: check(U, ....

L. Monteiro and A. Porto, Contextual Logic Programming, In Proceedings of the 6th International Conference on Logic Programming, In G. Levi and M. Martelli (Eds), pages 481--494, MIT Press, 1989.

.... extend logic programming with more sophisticated notions of modules inspired by other logics, such as intuitionistic logic [Miller 1989] or modal logic [Giordano and Martelli 1991] Finally, several other extensions of logic programming, such as the paradigm of contextual logic programming [Monteiro and Porto 1989], rely on the possibility of defining systems consisting of separate logic programs to be combined together. The applications of this class of extensions include forms of object oriented programming [Mello and Natali 1986] hypothetical reasoning [Miller 1989] and hierarchical reasoning [Monteiro ....

....logic is adopted to explain modularity, while in our approach we tackled modularity with the basic tools of logic programming. Similar considerations hold for the proposal of Giordano and Martelli [Giordano and Martelli 1991] where a modal logic is adopted. Monteiro and Porto introduced in [Monteiro and Porto 1989] Contextual Logic Programming. The basic idea is to partition a program into a collection of units, which are viewed as sets of context dependent predicate definitions. Units may be dynamically combined by means of one operation, which can occur in clause bodies. Contexts may be viewed as a ....

Monteiro, L. and Porto, A. 1989. Contextual logic programming. In G. Levi and M. Martelli (Eds.), Proceedings Sixth International Conference on Logic Programming, pp. 284--302. The MIT Press.

....the other hand, the correctness of the partial evaluation strategy employed is not discussed at all. Bugliesi, Lamma and Mello [10] also studied the problem of applying partial evaluation techniques to specialising compositions of object logic programs in the contextual logic programming setting [36]. Their approach neatly differs from ours in that all the definitions and results for partial evaluation in logic programming presented in [31] are extended in [10] to deal with the extended multi program setting. Definitions of extended resultant, extended SLD tree, and so on, are introduced, and ....

L. Monteiro and A. Porto. Contextual logic programming. In G. Levi and M. Martelli, editors, Proceedings Sixth International Conference on Logic Programming, pages 284--302. The MIT Press, 1989.

....s pluto) 5.2 Operational Semantics In this section, we discuss the operational semantics of MultiLog by presenting a goal directed sequent style proof system. This style of proof systems has also been adopted in languages such as Miller s module language [20] Contextual Logic Programming [21], SelfLog [3] ORLog [15] etc. The proof system is defined as a set of properties for the two proof predicates and . This structure essentially gives rise to a two tier proof system. The proof relation defines the provability of non b atoms in general and defines the provability of ....

....cau visibility. The fir visibility is trivially captured by deduction g rule. The provability in any mode ( is equivalent to the general provability ( if the goal G is conjunctive, empty, or a b atom. This observation leads to the inclusion of the deduction b rule. As usual, and as in [21, 20, 4], a proof for h Delta; ui G is a tree, called the proof tree, rooted at h Delta; ui G with internal nodes that are instances of one of the above rules, and with leaf nodes that are labeled with the figure empty. The height of a proof is the maximum of the number of nodes in all the branches ....

L. Monteiro and A. Porto. Contextual Logic Programming. In 6th ALP Intl. Conf. on Logic Programming, 1989.

....be a program and not a generic expression. This is due to the need of granting the programmer control over the actual (not virtual) clauses which will be involved in the operation. 4 The introduction of inheritance features into logic programming has been proposed by other authors (e.g. see [2, 17]) The restriction operator defined here is more primitive and it can be used with the other operations for the re construction of the other proposals. Indeed, in section 3, we will show the re construction of the proposal by Monteiro and Porto [17] Q A P (A in Q) The last rule defines the ....

....has been proposed by other authors (e.g. see [2, 17] The restriction operator defined here is more primitive and it can be used with the other operations for the re construction of the other proposals. Indeed, in section 3, we will show the re construction of the proposal by Monteiro and Porto [17]. Q A P (A in Q) The last rule defines the kind of amalgamation supported by the language. Namely, solving an extended goal of the form A in Q simply amounts to solving A in the program expression Q. 2.3 Bottom up Semantics We now define the denotational semantics of the amalgamated ....

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L. Monteiro and A. Porto. Contextual logic programming. In G. Levi and M. Martelli, editors, Proceedings Sixth International Conference on Logic Programming, pages 284-- 302. The MIT Press, 1989.

....Implementing contexts in logic programming E. Denti, E. Lamma, P. Mello, A. Natali, A. Omicini DEIS, University of Bologna Viale Risorgimento 2 40136 Bologna Italy Premise The concept of context and contextual programming has been recently introduced [MP89,LMN89,MNR89] in the logic programming field in order to enrich logic languages with general purpose concepts and mechanisms to structure programs, to support quick prototyping techniques and to promote the design and development of open, extensible software components. The key idea of contextual logic ....

....to the terminology reported in [MNR89] the eager binding mechanism allows users to define software components according to conservative architectures, while lazy binding supports evolving, open architectures. Contexts have been deeply studied in the last years both from the semantic (see [MP89,BLM90a]) and the implementative side [LMN89,LMN] In the following two related works, we describe our main results concerning the implementation of the context abstraction as an extension of Prolog. In particular, three main approaches have been considered, which can be summarized as follows: 1) ....

[Article contains additional citation context not shown here]

L. MONTEIRO, A. PORTO, Contextual Logic Programming, in Proceedings of the Sixth International Conference of Logic Programming, Lisboa, Portugal, June 1989.

No context found.

L. Monteiro and A. Porto. Contextual logic programming. In Proc. of ICLP'89, pages 284-299. MIT Press, Cambridge, MA, 1989.

No context found.

L. Monteiro and A. Porto. Contextual logic programming. In G. Levi and M. Martelli, editors, Logic Programming: Proc. of the Sixth International Conference, pages 284-299. MIT Press, Cambridge, MA, 1989.

No context found.

L. Monteiro and A. Porto. Contextual Logic Programming. In Proc. of the 6th International Conference of Logic Programming, ICLP'89, pages 284--299, Lisbon, 1989.

No context found.

A. Porto and L. Monteiro. `Contextual logic programming'. in G. Levi and M. Martelli (eds). Proceedings of the 6th lnternational Conference on Logic Programming, Lisbon. The MIT Press, Cambridge. Massachusetts, 1989. pp. 284--299.

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