A IT-KACI, H., & R. NASR. 1986. LOGIN: A logic programming language with built-in inheritance. Journal of Logic Programming 3.185--215.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....as a stream of messages) communicated between processes. The constraint satisfaction problem can be solved mostly (though not entirely) as a unification problem over feature graphs (feature structures with cycles) and can be solved in almost linear time with respect to the size of the program [2]. As we will see later, types in Moded Flat GHC also can be reconstructed using a similar (and simpler) technique. 1.2 Debugging by Constraint Based Mode and Type System Compared with abstract interpretation usually employed for the precise analysis of program properties, constraint based ....

....m #a, 3# = m #a, 2# m #a, 3##. 1# = m #a, 1##. 1# We could regard these constraints themselves as representing the principal mode of the program, but the principal mode can be represented more explicitly in terms of a mode graph (Figure 2. 3) Mode graphs are a kind of feature graphs [2] in which 1. a path (in the graph theoretic sense) represents a member of PAtom , 2. the node corresponding to a path p represents the value of m(p) # = in, out) symbol and an argument position, and may have an inversion bubble (denoted . in Figure 2.3) that inverts the ....

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H. At-Kaci and R. Nasr. LOGIN: A Logic Programming Language with Built-In Inheritance. J. Logic Programming, 3(3):185--215, 1986.

....formalisms like the Ordered Theories of [17] in modular languages such as Contextual Logic Programming [23, 24] and several others. However, the framework in which they accomplish this are quite narrow compared to the needs of object oriented databases and languages. Logic languages like LOGIN [1] and LIFE [2] incorporate structural inheritance by means of an extended uni cation algorithm for terms, complex typed structures that are used for data representation. Kifer et al. 16] proposed an elegant logic, called F logic, as a logical foundation for object oriented databases. Only ....

H. At-Kaci and R. Nasr. LOGIN: a logic programming language with built-in inheritance. Journal of Logic Programming, 3:182-215, 1986.

.... of communication protocols between concurrent processes [8] The constraint satisfaction problem can be solved mostly (though not entirely) as a unification problem over feature graphs (feature structures with cycles) and can be solved in almost linear time with respect to the size of the program [1]. As we will see later, types also can be reconstructed using a similar (and simpler) technique. Compared with abstract interpretation usually employed for the precise analysis of program properties, constraint based formulation of the analysis of basic properties has a lot of advantages. ....

....entire definition, we obtain 53 constraints which are consistent. We could regard these constraints themselves as representing the principal mode of the program, but the principal mode can be represented more explicitly in terms of a mode graph (Fig. 2) Mode graphs are a kind of feature graphs [1] in which 5 # # (HF) m(p) in, for a function symbol occurring in h at p. HV) m p = IN , for a variable symbol occurring more than once in h at p and somewhere else. GV) If some variable occurs both in h at p and in G at p # , m(pq) in . BU) m #=k , 1# = m #=k , 2#, for a ....

At-Kaci, H. and Nasr, R., LOGIN: A Logic Programming Language with Built-In Inheritance. J. Logic Programming, Vol. 3, No. 3 (1986), pp. 185--215.

....They originated in the late seventies with so called unification grammars [15, 13] a by now popular family of declarative grammar formalisms for the description and processing of natural language. More recently, the use of feature descriptions in logic programming has been advocated and studied [3, 4, 5, 6, 21]. Essentially, feature descriptions provide a logical version of records, a data structure found in many programming languages. Feature descriptions have been proposed in various forms with various formalizations [1, 2, 14, 18, 11, 20, 7, 12] We will follow the logical approach pioneered by ....

H. Ait-Kaci and R. Nasr. LOGIN: A logic programming language with built-in inheritance. The Journal of Logic Programming, 3:185--215, 1986.

....Grammar [17] Shieber s patr ii formalism [46] and Johnson s Attribute Value Logic [16] employ boolean combinations of equations built from features (used as unary functions) atoms (used as constants) and variables. Kay s Functional Unification Grammar [24, 25, 26] Ait Kaci s Term Calculus [2, 3, 4], and Kasper and Rounds logic [23, 39] employ set denoting expressions, called feature terms in this paper, that come in different syntactic guises (Figure 2 gives an example) Feature terms have much in common with the concept descriptions of terminological logics [5, 33, 34] used in knowledge ....

....don t occur in OE to arbitrary elements of D . Hence has a solution in I. 2 6 Feature Terms We now introduce a new form of expressions, called feature terms, that denote sets in feature algebras. Feature terms generalize Kasper and Rounds feature descriptions [23, 39] and Ait Kaci s terms [2, 3, 4]. Here is the abstract syntax of feature terms: S; T Gamma a atom x variable p: S selection p divergence p#q agreement p q disagreement bottom top S u T intersection S t T union :S complement 9x(S) existential quantification: 23 The free variables of a feature term are ....

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H. Ait-Kaci and R. Nasr. LOGIN: A logic programming language with built-in inheritance. The Journal of Logic Programming, 3:185--215, 1986.

....constraints can be computed e#ciently as unification over feature graphs. For instance, adding a new constraint m p 1 = m p 2 causes the subgraph rooted at p 1 and the subgraph rooted at p 2 to be unified. A good news is that an e#cient unification algorithm for feature graphs has been established [1]. Figure 7 shows the mode graph of a quicksort program using di#erence lists. The second and the third clause of part checks the principal constructor of A and X using guard goals, so the moding rule of variables occurring in guard goals (not stated in this paper) constrains m(#part, 1#) and ....

....to handle them so that they may remain consistent with the above intuitive meaning. 1. The annotations of constructors in program clauses and initial goal clauses are given according to how the structures they represent are implemented. For instance, consider the following goal clause: p([1,2,3,4,5],X) q( 1,2,3,4,5] X) If the implementation chooses to create a single instance of the list [1,2,3,4,5] and let the two goals share them, the constructors (there are 11 of them including [ must be given #. If two instances of the list are created and given to p and q, either annotation is ....

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At-Kaci, H. and Nasr, R., LOGIN: A Logic Programming Language with Built-In Inheritance. J. Logic Programming, Vol. 3, No. 3 (1986), pp. 185--215.

....in object oriented logic programming, as [Hen,1989] did for predicate calculus. We hope that, together with the present results, a better approach to procedural semantics will give birth to a valuable tool for solving many practical problems. We intend to follow the idea used by H. Ait Kaci in [AKN,1986] to manage inheritance at the unification level, in order to reduce the large number of resolution principles in F logic by incorporating their effect in a more elaborated unification process. As we are working now on a Prolog interpreter implementation in the object oriented language C (using ....

H.Ait-Kaci, R. Nasr, LOGIN: A Logic Programming Language with Built-in Inheritance, J. Logic Programming, 1986:3 p.185-215.

....studied; see [3] for a survey. For the LIGHT parsing system we adopted the Order Sorted Feature (OSF) constraint logic framework [2] In this way, typed uni cation grammars may be seen as a generalisation of De nite Clause Grammars (DCG, 7] similar to the way in which LOGIN generalised Prolog [1]. The aim of our work is to explore the usefulness of a logic based learning approach namely Inductive Logic Programming (ILP [6] to improve the coverage of a given typed uni cation grammar: we either generalise some rule or lexical type feature structures (FSs) in the grammar so to make ....

H. At-Kaci and R. Nasr. Login: A logic programming language with built-in inheritance. Journal of Logic Programming, 3:185-215, 1986.

.... emerged then to CFT [23] by incorporating arity constraints, and was finaly chosen to underlie the concurrent constraint object oriented language Oz [20] On the other side, feature constraints were used to express in a powerfull way logic records generalizing first order terms, namely terms [2] [3] 7] allowing for the sound use of the inheritance principle in the area of logic programming. This paper aims to enhance the previously mentioned work by reconsidering a (more complete) attempt to express the object orientation paradigm in logic, namely F logic [16] We preserve the F logic ....

....indexed on p 2 D and q 2 (D n0 (D n are binary relations on D , and p b q are unary relations on D . These restrictions lead to the fact that terms are defined upon a sort signature (C, which organize C as lower semi lattice, denoting here the sort intersection. As [2] shows, such a signature can always be constructed provided that : is a computably partial order relation on C. Let A be a DF algebra, A the reflexive and transitive closure of OE A , and ff : V a variable assignment in A extended as usually to constants from C. Satisfiability of DF atomic ....

H. Ait-Kaci, R. Nasr, LOGIN: A logic programming language with built-in inheritance, Journal of Logic Programming, 1986:3:185-215.

....program. Our approach to inheritance relates to previous work on inheritance in the context of (rule based) objectoriented languages as follows. Some of these approaches base inheritance on syntactic criteria, either on the class hierarchy alone [Bre87] on unification of terms denoting objects [AN86, CCCR 90] or on signatures [LO91] In [BM92] an additional labeling concept of rules affects inheritance. Other approaches consider inheritance as a model theoretic default mechanism [BL91, LV92, KLW90] The techniques we study are in some sense between these two directions. We use ....

H. Ait-Kaci and R. Nasr. LOGIN: A Logic Programming Language with Builtin Inheritance. In J. Logic Programming, 3, 1986.

....[28] and KL TWO [29] use the notion of the hierarchy of concepts in their terminological component, and a FOPC based language in their assertional one. The unification algorithm is extended to take the information in the terminological component into account. Also, systems like [24] LOGIN [30] and Taxlog [27] employ a lattice hierarchy of sorts alongside a FOPC based component, and extend their unification algorithm to take into account sortal information, but in a different way from the former systems. SILO uses extensions similar to those in the latter systems. All these systems, ....

H. Ait-Kaci and R. Nasr, LOGIN: A Logic Programming Language with Built-in Inheritance, Journal of Logic Programming 3 (1986) 185-215.

....day(x : dates) integers month(x : dates) monthnames year(x : dates) integers 32 Note that all this can be written very easily as a frame or record like structure, i.e. the attributes are regarded as selectors for compound objects. Then the above example reads in the notion of [1] as follows. person (ident ) strings, born ) dates ( day ) integers, month ) monthnames, year ) integers) father ) persons ) In fact, this treatment of attributes corresponds to the way Smolka and Ait Kaci remodelled Ait Kaci s inheritance hierarchies in order sorted equational logic ....

....is greater than 1910 the answer is no. Observe that all but the initial step are simplifications. Again, it is important to note, that no syntactic sugar was scattered until now. However, it is easy to introduce additional language constructs which allow the notation of John s attributes as in [1]. john: persons (ident ) smith, born ) dates( day ) may ) year ) 1928 ) Note that this notation does not imply that persons has a fixed number of attributes; by adding additional equations new attributes can easily be introduced. 4.2 Inheritance In a hierarchy of structured objects an ....

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H. Ait-Kaci and R. Nasr. Login: A logic programming language with built-in inheritance. Journal of Logic Programming, 3:187--215, 1986. 37

....account for the distinction between the schema and instance levels, and provide the notion of object state. A complete survey of approaches we have classified in group 1 may be found in [28] The above classification is of course rather arbitrary and non strict. For example the language LOGIN [7] is an object oriented extension of Prolog, which considers as object granularity that of term. Since this work greatly influences works on logics for objects developed in the database field, we deal with it in Subsection 2.2. 2.1 From Logic Programming to Modular and Object oriented Logic ....

....approaches we classify in this subsection consider objects as terms and do not take into account state evolution of objects. These proposals originate from Maier s O logic [45] and evolve in Clogic [34] and the revised O logic [42] These proposals are also strictly related to the LOGIN language [7]. The final effort in this direction, which extends the previous ones, is Frame Logic (Flogic) 41] It extends previous works with higher order features to accommodate methods within complex terms. The motivations underlying those approaches is the development of a logical framework for ....

H. AJt-Kaci and R. Nasr. Login: a Logic Programming Language With Built-In Inheritance. Journal of Logic Programming, 3:185 215, 1986.

....natural language [25, 27, 49] In programming languages, attribute value combinations are used in record structures. At Kaci was the first to study such structures mathematically, calling them # terms [2] The resulting term calculus is the formal foundation of the programming languages LOGIN [3] and LIFE [4] which are similar to PROLOG, but use feature unification [51] instead of syntactic unification. In contrast to several description logics, attributes in terms are functional : they can have only one value. This is convenient, since objects can be identified by some unique attribute ....

At-Kaci, H., and Nasr, R. Login: A logic programming language with built-in inheritance. Journal of Logic Programming

....theviewthatfeatures (correspondingtoourrecordflelds)arepartial functionsthatidentifyattributes. Not beingbasedon treestructures,featuresallow thedescription ofself referentialdatastructures.As opposedtoourapproach,thevalues designatedarenotguidedby any expressions. The programminglanguagesin[1,2]and[3]usesimilarideasandpermits circulardatastructures.A restrictionofthisworkisthatsuc h circular referencesmay onlypointtonodeslabeledsyntacticallywithamarker.Since thenumberofmarkersisflnite,thislanguageprecludesthemodeling ofe.g. doubly linkedlistsorleaf linkedtrees,butallows root linkedtrees. ....

H. A#t-Kaciand R. Nasr.Login:A logicprogramminglanguagewith built-ininheritance.JournalofLogicProgramming, 3:185-215,1986. Journalversionof[1].

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A IT-KACI, H., & R. NASR. 1986. LOGIN: A logic programming language with built-in inheritance. Journal of Logic Programming 3.185--215.

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H. At-Kaci and R. Nasr. LOGIN: A logic programming language with built-in inheritance. J. of Logic Programming, 3:185--215, 1986.

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) H. At-Kaci and R. Nasr. LOGIN: A logic programming language with built-in inheritance. Journal of Logic Programming, pages 185--215, 1986.

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H. Ait-Kaci, R. Nasr, LOGIN: A Logic Programming Language with Built-in Inheritance, Journal of Logic Programming, 1986:3, pp185-215.

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At-Kaci & R. Nasr: "LOGIN: A Logic Programming Language with Built-in Inheritance", Journal of Logic Programming 3(3), pp. 187-215, 1986.

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H.Ait-Kaci, R.Nasr, LOGIN: A Logic Programming Language with Built-in Inheritance, J. Logic Programming, 1986:3, pp185-215.

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Aït-Kaçi, H., Nasr, R., LOGIN: A Logic Programming Language with Built-in Inheritance, journal of Logic Programming, vol. 3, pp 185-215, 1986.

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