Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....one of the rules on the left. In many Prolog programs a list is used to store a set of resources on which the program relies, and this set is managed in a manner corresponding to the constraint on assumptions in linear logic. Consider the solution to the NQueens problem given in The Art Of Prolog [9], which is shown in Figure 1. In this program, a list is used to store terms corresponding to the rows of the chess board. For each column of the board, we select an unused row and test if it is safe to place the queen there. The list is managed to insure that each row is only used once. ....

....that with appropriate implementation techniques, these logics could yield solutions to some problems whose performance would be better than the traditional solutions. The LLPAM is the first system to fulfill that promise. The standard solution of the N Queens problem as presented in Art of Prolog [9] and given in Figure 1 makes natural use of resources. Because these resources are managed in a list structure, there is little the compiler can do to optimize the resource management. The rendition of this problem in Lolli as given in Figure 2 makes similar conceptual use of resources, increasing ....

Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, Cambridge MA, 1986.

....transitions have been represented as numbers. The same e institution is, of course, amenable to di erent visual renditions. 2.1 Representing E Institutions We can devise a simple and natural way to represent institutions almost directly translating the de nitions above. We shall employ Prolog [1, 24]: this way our representation will already be in a computer processable format. This would make it easier to extract our design patterns, as we shall roles(auction room, bidder,auctioneer] states(auction room, w0,w1,w2,w3,w4,w5,w6,w7,w8,w9] initial state(auction room,w0) final ....

....the head of which uni es with State, that is, all the transitions leaving State. After this, choose ChosenBody from Bodies via predicate chooseB=2 (to be de ned by the designers) and meta interpret it via meta=1. The remaining clauses follow the usual de nition for a Prolog meta interpreter [1, 11, 24]. 6. CONCLUSIONS AND DIRECTIONS OF RESEARCH In this paper we have presented a novel manner of programming agents. We speci cally address the context in which agents have to be designed to follow an electronic institution (e institution, for short) An initial design pattern is automatically ....

L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 2nd edition, 1994.

.... reverse can be written as follows in Oz: of nil then Zs=Ys [ X Xr then Zr in Zs=X Zr Append Xr Ys Zr end of nil then Ys=nil [ X Xr then R in NRev Xr R Append R [X] Ys This syntax should be vaguely familiar to people with some knowledge of Prolog and functional programming [111, 64, 113, 27]. We explain it briefly, pointing out where it di#ers from Prolog. All capitalized identifiers refer to logic variables in a constraint store. Append and NRev are procedures whose arguments are passed by unification, as in Prolog. The declare declares new global identifiers, Append and NRev, ....

....is an important extension for three reasons. First, it allows to do deterministic logic programming in a straightforward way. Second, it increases expressiveness by allowing powerful programming techniques based on incomplete data structures, such as tail recursive append and di#erence lists [24, 111]. The third reason is perhaps the most important: adding concurrency to this execution model gives a useful form of concurrent programming called declarative concurrency [122] 3 Nondeterministic logic programming We call nondeterministic logic programming the situation when search is used to ....

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Leon Sterling and Ehud Shapiro. The Art of Prolog--Advanced Programming Techniques. Series in Logic Programming. The MIT Press, 1986.

....the context of a single programming paradigm, embodied in a single language. The science is limited to the chosen paradigm or language. Some popular paradigms are objectoriented programming [23, 26, 27, 16] imperative programming [24] functional programming [11, 19, 7, 14, 25] logic programming [33, 8], and concurrent imperative programming [4, 5] Only the textbooks on functional programming and concurrent imperative programming give a formal semantics. Some languages are Java [23, 26, 22, 6] C [34] Ei#el [27] Prolog [33, 8] Erlang [5] Objective Caml [10] and Leda [9] Leda is ....

....functional programming [11, 19, 7, 14, 25] logic programming [33, 8] and concurrent imperative programming [4, 5] Only the textbooks on functional programming and concurrent imperative programming give a formal semantics. Some languages are Java [23, 26, 22, 6] C [34] Ei#el [27] Prolog [33, 8], Erlang [5] Objective Caml [10] and Leda [9] Leda is presented as a multiparadigm language but it contains only a few paradigms and these are presented in isolation. Teaching programming in terms of a single paradigm or language has a detrimental e#ect on programmer competence and thus on ....

Leon Sterling and Ehud Shapiro. The Art of Prolog--Advanced Programming Techniques. Series in Logic Programming. The MIT Press, 1986.

....Constraints can be treated as inference rules. When viewed as a backward chaining rule, a constraint can provide a channel for information flow between types of situations, from the antecedent to the consequent. This means that such a constraint behaves as a definition for its consequent part [47]. Another way of viewing a constraint is as a forward chaining rule. This approach enables an agent to alter its environment. 3.1 Approaches to Computational Situation Theory 3.1.1 PROSIT PROSIT (PROgramming in SItuation Theory) is the pioneering work in this direction. PROSIT is a ....

....situations. It is also possible to define relations between situations in the form of constraints. PROSIT s computational power is due to an ability to draw inferences via rules of inference which are actually constraints of some type. There is an inference engine similar to a Prolog interpreter [47]. PROSIT offers a treatment of partial objects, such as situations and parameters. It can deal with self referential expressions [9] and their unification. One can assert facts that a situation will support. For example, if the situation S1 supports the fact that Bob is a young person, this can ....

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L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques, Cambridge, Mass.: MIT Press, 1986.

.... concisely express certain other biases, in particular language biases like ij determinacy [Muggleton and Feng, 1992] or k locality [Cohen, 1994b] Because of this limitation the extension of augmented ADGs was proposed [Cohen, 1993c] Augmented ADGs are analogous to definite clause grammars [Sterling and Shapiro, 1986]. An augmented ADG is a theory Delta together with a series of rules of the form S T 1 ; T k where C 1 ; C n Formally, this rule allows replacing the symbol S with the sequence of symbols T 1 ; T k , where is some substitution such that Delta C 1 : C n . ....

Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.

....than letters of a finite alphabet, we will henceforth use the terms symbol, terminal, and nonterminal to denote symbols, terminals, and nonterminals respectively. In this paper, antecedent description grammars will be shown in a notation similar to that used for definite clause grammars [ Sterling and Shapiro, 1986, Chapter 16 ] this parallels the notation used in the implementation. In particular, the terminal symbols of the language, which are all literals, are enclosed in square brackets: for example, adj(X,Y) All other literals are nonterminal symbols. Commas denote concatenation. An empty pair ....

Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.

....this is an adaptation of the short cut deforestation introduced by Gill et al. 7] The goal of deforestation is the removal of some intermediate list used to compute the result. Optimization by Accumulating Parameters: this technique achieves a similar e ect than logic di erence lists [15, 14] but over functional (logic) functions. The goal is to optimize functions which build independently sections of a list to be later combined together by a concatenation. Our prototype system optimizes FlatCurry programs, i.e. programs written in the standard intermediate Curry language [9, 11] ....

....partial evaluation algorithm to produce more ecient residual functions. 3 Optimization by Accumulating Parameter This transformation optimizes functions that independently build di erent sections of a list to be later combined together. It achieves the same e ect than logic di erence lists [15, 14] but over functional logic programs. The main idea is to remove concatenation operations from a program by introducing accumulating parameters which allow to compute the result. For conceptual clarity, we structure our complete transformation in several stages. A complete and formal description of ....

L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986. 8

....One could also investigate the relationship of our approach to other approaches using unfolding resp. folding transformations. In the case of de nite logic programs and the implementation of Prolog, the use of unfolding and folding transformations has yielded nice performance improvements [SS94]. It is perhaps possible to get improved implementations of the well founded semantics by using the xpoint completion of [DK89] and the results obtained in this paper. The last approach for further research to be mentioned is the use of multivalued logic in logic programming semantics. Very ....

L. Sterling, E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1994.

....#Prolog and its module facilities to achieve an economical implementation of all the calculi discussed in this paper. We also summarize relevant correctness statements. 7. 1 #Prolog in a Nutshell We shall assume the reader familiar with the logic programming language Prolog, for which we adopt [SS94] as a reference. We will instead illustrate some of the characteristic constructs of #Prolog at an intuitive level. We invite the interested reader to consult [Mil96] for a more complete discussion of this language, and [CM99] for a detailed presentation in the context of the Event Calculus. ....

Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques.

....special class of propositional Bayesian logic programs, well known under the name Bayesian networks, and applied on general Bayesian logic programs. Before concluding the paper, we relate our approach to other work in Section 5. We assume some familiarity with logic programming or Prolog (see e.g. [26, 18]) as well as with Bayesian networks (see e.g. 23, 2] 2 Bayesian Logic Programs Throughout the paper we will use an example from genetics which is inspired by Friedman et al. 6] it is a genetic model of the inheritance of a single gene that determines a person s X blood type bt(X) Each ....

L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. The MIT Press, 1986.

....on this, we present a gradient based and an EM method to nd that parameters which maximize the likelihood. Section 6 reports on rst experiments. Before concluding the paper, we relate our approach to other work in Section 7. We assume some familiarity with logic programming or Prolog (see e.g. SS86,Llo89] as well as with Bayesian networks (see e.g. Pea91,CDLS99,Jen01] 2. Bayesian Logic Programs Throughout the paper we will use an example from genetics which is inspired by Friedman et al. FGKP99] it is a genetic model of the inheritance of a single gene that determines a person s X ....

L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. The MIT Press, 1986.

....more practical programming language that has evolved over the years. In response to the requirements imposed by applications, a number of extra logical features have been grafted to the base language. These features encourage a number of programming paradigms that are foreign to the pure subset. Sterling 86] gives a thorough grounding in the techniques of programming in this language, which we will call standard Prolog. We use the pure subset of Prolog as the starting point of our language design for three reasons. First, the subset is easy to characterize formally. This is an advantage since we ....

L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, Cambridge, MA, October 1986.

....2. Further, this form is assumed not to have side effects. Similarly for builtins, etc. in the RHS of a FC axiom. Rvariables are bound directly, and destructively, in the rvariable structure, more in formation is given in section 3.3. 1 [Bruynooghe, 1982] Mellish, 1982] Kahn and Carlsson, 1984] [Sterling and Shapiro, 1986]. All internal functions and builtins handle arguments that have this structure, such that intelligent backtracking [Warren, 1986] Bruynooghe and Peteira, 1984] Cox, 1984] can be implemented. The idea is that all functions that can backtrack take a failure continuation as an argument. If they ....

Leon Sterling and Ehud Shapiro, The Art of Prolog: Advanced Programming Techniques, MIT Press Series in Logic Programming. MIT Press, Cambridge, Massachusetts, 1986.

....of the development life cycle. One important characteristic of our system is the concept of representational independence: while the conceptual and representational constructs can combined in a flexible way in the modeling environment, they are implemented separately. The use of Prolog (e.g. [13, 3, 2, 23]) for completely building our CASE environment is essential to our approach. First, the declarative nature of Prolog offers, of course, several well known advantages over conventional programming languages such as clarity, modularity, conciseness, and legibility. As a result, programs are much ....

L. Sterling and E. Shapiro. The Art of Prolog - Advanced Programming Techniques. MIT, 1986.

....logical relations. This means that, although template calls may be embedded into template denitions, there must be neither direct nor indirect selfreference in template denitions. Hence, templates realize the database programming part of a logic programming language like Prolog (cf. [18]) A simple scheme PrepPhrase of a prepositional phrase which consists only of a preposition (APPR) and a proper noun (NE) PP APPR NE (9.1) can be dened as follows: PrepPhrase(#n0) #n0: cat= PP ] #n1: pos= APPR ] The arrow marks a dening clause of a template denition. The ....

Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, Cambridge, Mass., 1986.

....Section 5 we describe how our type system can be used to eliminate run time errors, and nally in Section 6 the implementation of our system is shortly discussed. We assume that the reader is familiar with basic concepts concerning logic programming and Prolog (presented for instance in [2] and [20]) 2. TYPES OF TERMS Let V be the set of program variables (denoted by letters X; Y; the set of term constructors (denoted by f; g; V T the set of type variables (denoted by ; T the set of type constructors (like int, real list, tree, denoted by F; G; ....

....is given in the next section where implementation of our system is discussed. 6. IMPLEMENTATION Our type system (including the type checking and constrained type reconstruction algorithm) has been implemented in C . We tested our implementation on predicates from the Sterling Shapiro book [20]. In spite of the high theoretical complexity type checking and type reconstruction algorithms performs quite well. Reconstruction of the main type for a program with 74 predicates, 151 clauses and 497 lines took on computer PC with Pentium II and gcc compiler less then 2 seconds. Besides Prolog ....

E. Shapiro and L. Sterling. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1994.

....effective parsers. Even though the control structure of Prolog matches directly that of recursive descent, top down parsers, other parsing algorithms can also be implemented in it quite easily. For example, Matsumoto et al. 1986) describes a bottom up parser in Prolog. 1 (Da [SS87], pagg. 256 265) Metamorphosis grammars [ is the name invented by Colmerauer (1975, 1978) The name definite clause grammars was later introduced by Pereira and Warren (1980) for metamorphosis grammars in normal form (as defined by Colmerauer) Da [KS85] pag. 68) The Prolog ....

.... ,XnY) preproc(B,B 1 ,YnZ) preproc(A,A 1 ,S) nonTerminale(A) functor(A 1 ,A,1) arg(1,A 1 ,S) preproc(X,true,S) terminali(X) seq(X,S) nonTerminale(A) atom(A) terminali( X Y] seq( X Y] X S]nS 0 ) seq(Y,SnS 0 ) seq( XnX) 4 Questo preprocessore e preso da [SS87], pag.259, e tratta solamente produz con un unica alternativa come latoDx. 9 (Si noti che la preproc definita dalla prima clausola, che ha due argomenti, sfrutta un altra preproc a tre argomenti) Esercizio 9 Si estenda il preprocessore in modo che tratti anche produz con pi u di un alternativa ....

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L. Sterling, E. Shapiro. The Art of Prolog - Advanced programming techniques. Series in Logic Programming, The MIT Press, Cambridge, Massachusetts, 1987. 3rd printing. 22

....Therefore, we are interested in a transformation process in which the nal program does not contain occurrences of di erence lists. To achieve this goal, we considered that, in some cases, programs using di erence lists are structurally similar to programs written using accumulating parameters [13]. We will show that this idea can be generalized, giving rise to an optimization technique which achieves a similar e ect over functional logic programs and always returns a program without di erence lists. After some preliminary de nitions in the next section, we describe the development of a ....

.... to apply the rst equation: isShorter (x:xs) z ; fz7 y:ysg isShorter xs ys ; fxs7 [ g True 3 Optimization by Accumulating Parameters In this section, we introduce a new transformation for optimizing functions that independently build di erent sections of a list to be later combined together [13]. The development is inspired by the well known di erence list transformation from the logic programming community [12, 13] The idea behind the di erencelist transformation of [12] is to replace certain lists by terms called di erencelists in order to expose opportunities for a faster ....

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L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.

....we are interested in a transformation process in which the final program does not contain occurrences of difference lists. To achieve this goal, we considered that, in some cases, programs using difference lists are structurally similar to programs written using accumulating parameters [15]. We will show that this idea can be generalized, giving rise to an optimization technique which achieves a similar effect over functional logic programs and always returns a program without difference lists. The main contributions of this work are: the adaptation of short cut deforestation to ....

.... with the proof of correctness, can be found in the extended version of this abstract [1] 4 Optimization by Accumulating Parameters In this section, we introduce a new transformation for optimizing functions that independently build different sections of a list to be later combined together [15]. The development is inspired by the well known difference list transformation from the logic programming community [14, 15] The idea behind the difference list transformation of [14] is to replace certain lists by terms called difference lists in order to expose opportunities for a faster ....

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L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.

....the Gabriel benchmarks (as translated by T. Dobry and H. Touati) deriv performs symbolic differentiation of an equation; grammar is a program that generates and recognizes a small set of English; icomp is a code generator for the WAM, written by Demoen; kalah is the Kalah playing program from Sterling and Shapiro [1994] which uses alpha beta pruning; mapcolor is a map coloring program for a map representation of six countries; peephole is the ACM Transactions on Programming Languages and Systems, Vol. 18, No. 5, September 1996. Global Analysis of Constraint Logic Programs Delta 611 optimizer of SB Prolog, ....

Sterling, L. and Shapiro, E. 1994. The Art of Prolog: Advanced Programming Techniques, 2nd ed. Logic Programming Series. MIT Press, Cambridge, Mass.

....populate the database. The presence of a static analyzer simpli es descriptions and relieves the authors of language descriptions from specifying many details. 5. 2 LCGs and Logic Programming Making LCGs practical required several modi cations to the basic Prolog model of logic programming [60]. Partitioned Database. The logic database is explicitly structured into collections of data tuples. Collections and data tuples are rst class objects: they can be created and destroyed dynamically. Collections are created and data tuples are added to collections as a side e ect of satisfying a ....

Sterling, L., and Shapiro, E. The Art of Prolog: Advanced Programming Techniques. The MIT Press, Cambridge, Massachusetts and London, England, 1986.

....logic (FOPL) to Horn clause form logic and to Prolog, and the implementation of negation, assertion and retraction. Solutions to them form the foundation of the operational logics used in formal methods [4] 5] 6] 11] for software engineering. Profound research results on logics are found in [2] 7][10]. From the point of view of pure logics, the above computational issues have been solved. The soundness of logic programming encourages researchers to use logics in software engineering. On the other hand, few works have made noticeable achievement in the software engineering eld. Researchers in ....

L. Sterling, E. Shapiro, The Art of Prolog: Advanced Programming Techniques, The MIT Press, 1986.

....search) Since intuitionistic provability admits goal directed theorem provers in this setting, we shall refer to the triple L = hD; G; I i as a logic programming language. In presenting example programs and goals of L, we shall use a slightly extended version of usual Prolog syntax [22]. In particular, we use the symbol = for implications at the top level of goals. Thus, we have two notations for implication: is the converse of : When denoting Horn clauses, explicit quantifiers are generally not needed, while in L, quantifiers in both D and G formulas must often be made ....

....set of Sigma; A sequents. These sequents specify what remains to be proved. A success state is a state in which the set of sequents is empty. We assume the usual notions of substitution into first order (quantified) formulas, first order unification, and most general unifiers (see, for example, [22]) Simultaneous substitutions are denoted as [x 1 7 t 1 ; xn 7 t n ] A simple elaboration function elab that maps D to finite subsets of D is defined using the equations 4. An interpreter for L 14 May 1997 ffi elab(A) fAg, ffi elab(G oe A) fG oe Ag, ffi elab(D 1 D 2 ) elab(D ....

L. Sterling and E. Shapiro, The art of Prolog: advanced programming techniques, MIT Press, Cambridge MA, 1986.

....previous section, we proposed a general notion of constructive object creation in terms of hereditarily finite sets. In practice however, data structures are often implemented using lists rather than sets. This is for example the case in functional programming [1] as well as in logic programming [29] where first order term structures are used for this purpose. Approaches to object creation as first order term construction have been considered in the literature [25, 26] In order to characterize the expressive power of languages that base object creation on lists rather than sets, we propose ....

L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.

....The outline of the language is provided mainly as a means of introducing the reader to the terminology that will be used in this paper. It is assumed that the reader already has at least some familiarity with logic programming and first order logic. Sterling and Shapiro s The Art of Prolog [34] and Maier and Warren s 1 Computing With Logic [27] are both excellent introductions to these areas; in addition the latter includes a good treatment of Prolog interpretation and compilation issues. In order to recognize the subtle di#erences between Prolog compilation and that of other ....

....The prover begins by trying to replace the subgoal A 1 , and does so using the first rule shown. The current goal is 4 This description of the Prolog proof procedure is based largely on one given by Bruynooghe [11] 5 The unification algorithm is described well in chapter 4 of The Art of Prolog [34] 3 then [C 1 ,C 2 ,C 3 ,A 2 ,A 3 ]# 1 . The prover again selects the leftmost subgoal, C 1 ]# 1 , and attempts to prove it. Assuming that this formula unifies with D 1 under the substitution # 3 , the goal becomes [ C 2 ,C 3 ,A 2 ,A 3 ]# 1 ]# 3 . If no clause is found whose head unifies with ....

Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press Series in Logic Programming. The MIT Press, Cambridge, Massachusetts, 1986.

....The second component is the quantitative one. It encodes the quantitative information about the domain and employs as in Bayesian nets the notions of conditional probability table (CPT) and combining rule (cf. below) We assume some familiarity with Prolog or logic programming (see e.g. [SS86]) as well as with Bayesian nets (see e.g. RN95] A Bayesian predicate is a predicate r to which a nite domain D r is associated. We de ne a Bayesian de nite clause as an expression of the form A j A 1 ; An where the A; A 1 ; An are logical atoms and all variables are ....

....random variables will be called relevant w.r.t. Q and the given Bayesian logic program. The relevant random variables are themselves the ground atoms needed to prove that Q is true (in the logical sense) The usual execution model of logic programs relies on the notion of SLD trees (see e.g. [Llo89, SS86]) For our purposes it is only important to realize that 8 This is a reasonable assumption if the Bayesian logic program has been written by anyone familiar with Prolog. 9 We neglect the niteness of Bayesian nets for the moment. u u e e e u e e Z Z Z = ....

L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. The MIT Press, 1986.

....logical relations. This means that, although template calls may be embedded into template denitions, there must be neither direct nor indirect selfreference in template denitions. Hence, templates realize the database programming part of a logic programming language like Prolog (cf. [18]) A simple scheme PrepPhrase of a prepositional phrase which consists only of a preposition (APPR) and a proper noun (NE) PP APPR NE (2.49) can be dened as follows: PrepPhrase(#n0) #n0: cat= PP ] #n1: pos= APPR ] #n0 #n2: pos= NE ] #n1.#n2 arity(#n0,2) The arrow marks ....

Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, Cambridge, Mass., 1986.

....in the graph have the same color. It is a practical CSP which has many useful applications. Production scheduling, construction of examination timetables, and the storages of goods can all be stated as graph coloring problems [31] We compare PROCLANN and CHIP on some graph coloring problems in [4, 12, 26] and a set of hard graph coloring problems described in [18] The PROCLANN graph coloring program is shown in figure 3. The results are presented in Tables 1 and 2 respectively. The CPU time reported in the tables is the median time 3 over ten runs. Note that the first fail principle [14] is used ....

L. Sterling and E. Shapiro. The Art of Prolog---Advanced Programming Techniques. The MIT Press, 1986.

....other is a theory of search developed in the constraint satisfaction literature, which deals with such topics as consistency, search orders, the dependency graph, and various measures of its width. Lloyd s text [107] provides a good introduction to logic programming, which is further exposited in [33, 140]. Tsang [141] provides excellent coverage of the theory of constraint satisfaction. Van Hentenryck [143] wrote an early exposition of constraint logic programming, while Marriott and Stuckey s text [110] is a valuable resource for recent work in constraint programming and constraint logic ....

Sterling, L., and E. Shapiro, The Art of Prolog: Advanced Programming Techniques, MIT Press (Cambridge, 1986).

....higher order notions in these paradigms. Towards filling this lacuna, this paper initiates investigations into a logical basis for higher order features in logic programming. The principal concern here is that of describing an extension to Horn clauses [33] the basis of languages such as Prolog [32], by using a higher order logic. The use of the term extension clearly signifies that there is some character of Horn clauses that is to be retained. This character may most conveniently be enunciated in the context of a generalized version of Horn clauses that is, in some senses, closer to ....

....programming languages unchanged and to provide some of the functionality of higher order features through special mechanisms built into the interpreter. This approach is exemplified by the presence of extra logical predicates such as univ and functor in most current implementations of Prolog [32]. While this approach has the advantage that usable higher order extensions may be provided rapidly, it has the drawbacks that the logical basis of the resulting language is no longer clear and, further, that the true nature and utility of higher order features within logic programming is ....

Sterling, L., and Shapiro, E. The Art of Prolog: Advanced Programming Techniques. MIT Press, Cambridge MA, 1986.

....of the output variables remaining within the stated limit. The limit can be changed by the user, but is currently set at 100. Examples enumeration limit 100 4 Example Programs 4. 1 The Mastermind Game This example was introduced as a non trivial programming problem by Sterling and Shapiro (Sterling Shapiro, 1986), and has also been the topic of other articles (e.g. Van Hentenryck, 1989; Merelo, 1996) The problem concerns the game of master enumeration limit [Variable] Constraint Handling in Common LISP 39 Example Programs mind, in which the object is for the code breaker to crack the opponent s ....

STERLING, L., SHAPIRO, E., (1986), "The Art of Prolog: Advanced Programming Techniques", MIT Press, Cambridge, MA, USA.

....we are interested in a transformation process in which the final program does not contain occurrences of difference lists. To achieve this goal, we considered that, in some cases, programs using difference lists are structurally similar to programs written using accumulating parameters [12]. Compare, for instance, an optimized version of quicksort by difference lists (see Sect. 4) qs( hys; ysi) qs(x:xs; hys; ys 0 i) Gamma split(x; xs; l; r) qs(l; hys; x:wi) qs(r; hw; ys 0 i) and by introducing accumulating parameters: qs acc ( ys; ys) qs acc (x:xs; ys 0 ; ....

.... reduce to the same ground constructor term) and constructor substitutions as solutions [4] 4 Optimization by Accumulating Parameters In this section, we introduce a new transformation for optimizing functions that independently build different sections of a list to be later combined together [12]. The development of this section is inspired by the well known difference list transformation from the logic programming community [11, 12] The idea behind the difference list transformation of [11] is to replace certain lists by terms called difference lists in order to expose opportunities ....

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L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.

....that the goal always succeeds (it has at least 3 solutions) and does not terminate (snt stands for sure non termination ) The number 3 comes from the widening on sequences which is applied when the abstract substitution part stabilizes. Finally, consider the meta program for unification from [16]. Given the input pattern unify(a,a) our analysis returns the abstract sequence hunify(a; a) 0; 1; pti in 0.02 seconds. The key issue is to collect information on the meta predicates to detect mutual exclusion. 2 unify(X,Y) var(X) var(Y) X = Y. unify(X,Y) var(X) nonvar(Y) X = Y. ....

L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, Cambridge, Ma, 1986. 14

....all other code and data constructors. This lack of abstraction will be one of the motivations for going beyond fohc. 20 3.5 Additional readings A background in using logic programming language, particularly Prolog, is assumed for much of these notes. To gain such a background, see the books [CM84, SS86]. A nice introduction to theory of first order Horn clauses, see [AvE82] 3.6 Exercises 1. Show that each of the following is true using all three definitions of first order Horn clauses. a) A definite clause is order 0 or 1. b) A goal formula is order 0. c) If a subformula of a definite ....

Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, Cambridge MA, 1986.

....clause with a single positive literal is a fact. A logic program P is a (possibly empty) set of clauses. The empty program is denoted by the symbol . In order to represent logic programs we will use, for convenience, an identical notation as the one used in the logic programming language Prolog [116]. The symbols for disjunction ( and conjunction ( are replaced by commas, and clause ends with a period. However, we differ from Prolog notation in one aspect: the implication arrow ( is used instead of Prolog s colon dash : A 1 , A 2 , Am B 1 , B 2 , B n . Variables are ....

Sterling, L., Shapiro, E. Y., (1986) The Art of Prolog: Advanced Programming Techniques. MIT Press.

....operations in mind. 2.2 Implementation Decisions 2.2.1 Implementation Language The COIN system was developed on the ECLiPSe 1 platform which is a parallel constraint logic programming environment with database capabilities. The kernel of ECLiPSe is an implementation of Standard Prolog [13]. The main reason for choosing Prolog as our implementation language was because of the adequacy of Prolog for implementing problems which involve a significant amount of symbolic manipulation. Moreover, this specific Prolog implementation gave us the added bonus of a multiindexing temporary data ....

Leon Sterling and Ehud Shapiro. The Art of Prolog : Advanced Programming Techniques. The MIT Press, 1994. 57

....TP ; 2 I M g. d) N is a set of literals of the form i) a l, with a is a constant, l a list and 2 I M nfisg. ii) X l, with X is a variable, l a list and 2 I M . N : fa l j a is a constant, l 2 T e [ ZP ; 2 I M nfisgg [ fX l j X is a variable, l 2 T e [ ZP ; 2 I M g. 8 Additional remarks [22]: 1. For arithmetic operations, assignments, and comparisons infix functors are used in general. The construction of lists can be done by [X jXs] where X is an atomic symbol, i.e. a variable or a constant, and Xs may be a symbol or again a list. 2. Literals may now also be operations with infix ....

L. Sterling, E. Shapiro, "The Art of Prolog, Advanced Programming Techniques", Massachusetts Institute of Technology, MIT Press, 1986

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Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.

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Ehud Shapiro and Leon Sterling. The Art of Prolog Advanced Programming Techniques. Prentice Hall - India, 1996.

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Sterling, L., and Shapiro, E. The Art of Prolog: Advanced Programming Techniques. MIT Press, Cambridge MA, 1986.

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Leon Sterling and Ehud Shapiro. The Art of Prolog Advanced Programming Techniques. Prentice Hall - India, 1996.

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Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press series in logic programming. The MIT Press, Cambridge, Massachusetts, second edition, 1986. Fourth printing.

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L. Sterling, E. Shapiro, The Art of Prolog: Advanced Programming Techniques, MIT Press, Cambridge, MA, 1986.

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L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. Series in Logic Programming. The MIT Press, 1986.

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Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. The MIT Press, 1986.

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L. Sterling and E. Y. Shapiro, The Art of Prolog: Advanced Programming Techniques, MIT Press, Cambridge, Massachusetts, 1986.

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L. Sterling and E. Shapiro, The Art of Prolog: Advanced Programming Techniques, MIT Press, Cambridge, MA, 1986.

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Leon Sterling and Ehud Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.

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L. Sterling and E. Shapiro. The Art of Prolog: Advanced Programming Techniques. MIT Press, 1986.

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