Filters








3,117 Hits in 2.5 sec

Smallest horn clause programs

P Devienne, P Lebègue, A Parrain, J.C Routier, J Würtz
1996 The Journal of Logic Programming  
Thus, we propose an equivalent of the B6hm-Jacopini theorem for logic programming. This result confirms the expressiveness of logic programming.  ...  Moreover, we prove that the computational power of append-like programs is equivalent to the one of Turing machines; we show that there exists an append-like universal program.  ...  There exists a meta-interpreter for Horn clauses in the form of a program with only one binary Horn clause, a fact and goal which, given as input a Horn clause program P, has the same solutions as P and  ... 
doi:10.1016/0743-1066(95)00122-0 fatcat:pjc23hpkefbhtfandrsbqgwjrm

Satisfiability of the smallest binary program

Philipp Hanschke, Jörg Würtz
1993 Information Processing Letters  
The simplest scheme of recursion in the context of logic programming is the binary Horn clause P (l 1 : : : l n ) P (r 1 : : : r n ) .  ...  The decidability of the satis ability problem of programs consisting of such a rule, a fact and a goal { called smallest binary program { has been a goal of research for some time.  ...  All further Horn clauses must be facts or binary.  ... 
doi:10.1016/0020-0190(93)90210-z fatcat:kny57wvv4neqnihzadtwysb6ei

Tradeoffs in the complexity of backdoors to satisfiability: dynamic sub-solvers and learning during search

Bistra Dilkina, Carla P. Gomes, Ashish Sabharwal
2014 Annals of Mathematics and Artificial Intelligence  
These syntactic classes, however, do not capture key aspects of solvers such as empty clause (i.e., violated constraint) detection.  ...  We also reveal the inherent limits of the simpler concept of deletion backdoors, specifically by looking at renamable Horn sub-formulas.  ...  A preliminary version of this article appeared at the 13th International Conference on Principles and Practice of Constraint Programming, Providence, RI in September 2007 [16] .  ... 
doi:10.1007/s10472-014-9407-9 fatcat:twcqxbtbybd2xmviixsstjhloa

Semantics of Horn and disjunctive logic programs

Jorge Lobo, Arcot Rajasekar, Jack Minker
1991 Theoretical Computer Science  
Horn programs.  ...  Minker, Semantics of Horn and disjunctive logic programs, Theoretical Computer Science 86 (1991) 93-106.  ...  A Horn program consists of only definite Horn clauses. An inde$nite or disjunctive clause is one where n 2 2. A logic program is a disjunctive program if it contains a disjunctive clause.  ... 
doi:10.1016/0304-3975(91)90006-n fatcat:caazixkcnfcrti5soh3jgiqsny

One binary horn clause is enough [chapter]

Philippe Devienne, Patrick Lebègue, Jean-Christophe Routier, Jörg Würtz
1994 Lecture Notes in Computer Science  
Indeed the simplest class of recursive programs in Horn clause languages can be de ned by the following scheme : ( A1 : A2 A3: that is 8x1 8xm A1^(A2 _ :A3)^:A4] A4: where Ai are positive rst{order literals  ...  Then, we prove e ectively by logical transformations that all conjunctive formulas of Horn clauses can be translated into an equivalent conjuctive 4{formula (as above).  ...  She contributes a lot to the work on meta{program. We would like to thank Philipp Hanschke for valuable discussions. Last, we would like to thank anonymous referees for their valuable comments.  ... 
doi:10.1007/3-540-57785-8_128 fatcat:tmlvtjswgnc6lbphbsgldz4wca

A Linear Programming Based Satisfiability Solver Using a New Horn-Driven Search Tree Design [chapter]

Linda van Norden, Hans van Maaren
2002 Lecture Notes in Computer Science  
Horn clauses are clauses in which at most one variables occurs in negated form. Therefore, formulae with only Horn clauses of size 2 and larger are always satisfied if all variables are set to true.  ...  The aim of the splitting is to obtain a formula that is clause to a Horn formula.  ... 
doi:10.1007/3-540-46135-3_71 fatcat:xin3g4slmbepxmfnvg2ihbrlcy

Page 266 of Mathematical Reviews Vol. 56, Issue 1 [page]

1978 Mathematical Reviews  
A lock-T proof of a clause C is a lock proof of C in which factoring only occurs in 7-clauses (i.e. clauses composed entirely of literals L whose ancestors A(L)¢7) and only on literals of smallest lock  ...  It is easy to see that every set of clauses is a Horn, set for various choices of T.  ... 

Horn Clause Solvers for Program Verification [chapter]

Nikolaj Bjørner, Arie Gurfinkel, Ken McMillan, Andrey Rybalchenko
2015 Lecture Notes in Computer Science  
This paper complements these strides as we summarize main useful properties of Horn clauses, illustrate encodings of procedural program verification into Horn clauses and then highlight a number of useful  ...  simplification strategies at the level of Horn clauses.  ...  Aggregates and Optimality Suppose we would like to say that a program has at most a 2 · n reachable states for a parameter n.  ... 
doi:10.1007/978-3-319-23534-9_2 fatcat:hsmmbrr35nfsveszovx67isifq

Learning acyclic first-order horn sentences from entailment [chapter]

Hiroki Arimura
1997 Lecture Notes in Computer Science  
Particularly, we deal with a subclass of rst-order Horn sentences AC H (k), called acyclic constrained Horn programs of constant arity k.  ...  This paper consider the problem of learning an unknown rst-order Horn sentence H 3 from examples of Horn clauses that H 3 implies and does not imply.  ...  For a Horn program H of H, the dependency relation for H is the smallest preorder > H such that a > H b holds for all instances (a B) of clauses and all subgoal b 2 B.  ... 
doi:10.1007/3-540-63577-7_59 fatcat:smapygorezdspbadae4yr4x62m

Page 2213 of Mathematical Reviews Vol. , Issue 93d [page]

1993 Mathematical Reviews  
Summary: “In this paper definite Horn clause programs are inves- tigated within a proof-theoretic framework, program clauses being considered rules of a formal system.  ...  The evaluation procedures for queries with respect to the defined extensions of definite Horn clause programs are shown to be sound and complete.  ... 

Fixpoint semantics for logic programming a survey

Melvin Fitting
2002 Theoretical Computer Science  
Nonetheless, much of the work on logic programming semantics seems to exist side by side with similar work done for imperative and functional programming, with relatively minimal contact between communities  ...  In this paper we summarize one variety of approaches to the semantics of logic programs: that based on ÿxpoint theory.  ...  A program clause is a Horn clause whose head is non-empty -it is allowed that the body be empty. Free variables in a Horn clause are thought of as universally quantiÿed.  ... 
doi:10.1016/s0304-3975(00)00330-3 fatcat:ec6vntnnu5eoflpgohb3qz5ylm

Horn clause queries and generalizations

Ashok K. Chandra, David Harel
1985 The Journal of Logic Programming  
A logic program consists of a set of Horn clauses, and can be used to express a query on relational data bases.  ...  Queries expressible by logic programs are thus not first-order queries in general, nor are all the first-order queries expressible as logic programs.  ...  This construction is very similar to that given in [l] for constructing the "IF version" associated with a Horn-clause program.  ... 
doi:10.1016/0743-1066(85)90002-0 fatcat:dms6nnhhtfgsbm7jus6wq5ibhe

Combining Forward and Backward Abstract Interpretation of Horn Clauses [article]

Alexey Bakhirkin
2017 arXiv   pre-print
The current state-of-the-art technique for combining forward (bottom-up, in logic programming terms) and backward (top-down) abstract interpretation of Horn clauses is query-answer transformation.  ...  It transforms a system of Horn clauses, such that standard forward analysis can propagate constraints both forward, and backward from a goal.  ...  Introduction In the past years, there has been much interest in using Horn clauses for program analysis, i.e., to encode the program semantics and the analysis questions as a system of Horn clauses and  ... 
arXiv:1707.01277v2 fatcat:2dr2p5uutvetnmunufzepy7wsa

Combining Forward and Backward Abstract Interpretation of Horn Clauses [chapter]

Alexey Bakhirkin, David Monniaux
2017 Lecture Notes in Computer Science  
The current state-ofthe-art technique for combining forward (bottom-up, in logic programming terms) and backward (top-down) abstract interpretation of Horn clauses is query-answer transformation.  ...  It transforms a system of Horn clauses, such that standard forward analysis can propagate constraints both forward, and backward from a goal.  ...  Introduction In the past years, there has been much interest in using Horn clauses for program analysis, i.e., to encode the program semantics and the analysis questions as a system of Horn clauses and  ... 
doi:10.1007/978-3-319-66706-5_2 fatcat:qyo5gssip5bzfoidczxuqok6de

Backdoors to tractable answer set programming

Johannes Klaus Fichte, Stefan Szeider
2015 Artificial Intelligence  
We show how this concept can be adapted to the nonmonotonic setting and how it allows to augment various known tractable subproblems, such as the evaluation of Horn and acyclic programs.  ...  We present a unifying approach to the efficient evaluation of propositional answer-set programs.  ...  Thus {r, s} is a smallest strong Horn * -backdoor of P .  ... 
doi:10.1016/j.artint.2014.12.001 fatcat:oq2lmou5vjg2llpxszd24jhfti
« Previous Showing results 1 — 15 out of 3,117 results