lambdaProlog is known to be well-suited for expressing and implementing logics and inference systems. We show that lemmas and definitions in such logics can be implemented with a great economy of expression. We encode...
详细信息
lambdaProlog is known to be well-suited for expressing and implementing logics and inference systems. We show that lemmas and definitions in such logics can be implemented with a great economy of expression. We encode a higher-order logic using an encoding that maps both terms and types of the object logic (higher-order logic) to terms of the metalanguage (lambdaProlog). We discuss both the Terzo and Teyjus implementations of lambdaProlog. We also encode the same logic in Twelf and compare the features of these two metalanguages for our purposes.
This paper illustrates how a Prolog program, using chronological backtracking to find a solution in some search space, can be enhanced to perforin intelligent backtracking. The enhancement crucially relics on the impu...
详细信息
This paper illustrates how a Prolog program, using chronological backtracking to find a solution in some search space, can be enhanced to perforin intelligent backtracking. The enhancement crucially relics on the impurity of Prolog that allows a program to store information when a dead end is reached. To illustrate the technique, a simple search program is enhanced.
In this paper, we propose a variant of stable model semantics for disjunctive logicprogramming and deductive databases. The semantics, called minimal founded, generalizes stable model semantics for normal (i.e. non-d...
详细信息
In this paper, we propose a variant of stable model semantics for disjunctive logicprogramming and deductive databases. The semantics, called minimal founded, generalizes stable model semantics for normal (i.e. non-disjunctive) programs, but differs from disjunctive stable model semantics (the extension of stable model semantics for disjunctive programs). Compared with disjunctive stable model semantics, minimal founded semantics seems to be more intuitive, it gives meaning to programs which are meaningless under stable model semantics and is no harder to compute. More specifically, minimal founded semantics differs from stable model semantics only for disjunctive programs having constraint rules or rules working as constraints. We study the expressive power of the semantics, and show that for general disjunctive datalog programs it has the same power as disjunctive stable model semantics.
The overall goal of this paper is to investigate the theoretical foundations of algorithmic verification techniques for first order linear logic specifications. The fragment of linear logic we consider in this paper i...
详细信息
The overall goal of this paper is to investigate the theoretical foundations of algorithmic verification techniques for first order linear logic specifications. The fragment of linear logic we consider in this paper is based on the linear logicprogramming language called LO (Andreoli and Pareschi, 1990) enriched with universally quantified goal formulas. Although LO was originally introduced as a theoretical foundation for extensions of logicprogramming languages, it can also be viewed as a very general language to specify a wide range of infinite-state concurrent systems (Andreoli, 1992;Cervesato, 1995). Our approach is based on the relation between backward reachability and provability highlighted in our previous work on propositional LO programs (Bozzano et al., 2002). Following this line of research, we define here a general framework for the bottom-up evaluation of first order linear logic specifications. The evaluation procedure is based on an effective fixpoint operator working on a symbolic representation of infinite collections of first order linear logic formulas. The theory of well quasi-orderings (Abdulla et al., 1996;Finkel and Schnoebelen, 2001) can be used to provide sufficient conditions for the termination of the evaluation of non trivial fragments of first order linear logic.
We study algorithms for computing stable models of logic programs and derive estimates on their worst-case performance that are asymptotically better than the trivial bound of O(m2(n)), where m is the size of an input...
详细信息
We study algorithms for computing stable models of logic programs and derive estimates on their worst-case performance that are asymptotically better than the trivial bound of O(m2(n)), where m is the size of an input program and n is the number of its atoms. For instance, for programs whose clauses consist of at most two literals (counting the head) we design an algorithm to compute stable models that works in time O(m x 1.44225(n)). We present similar results for several broader classes of programs. Finally, we study the applicability of the techniques developed in the paper to the analysis of the performance of smodels.
It is well known that freeness and linearity information positively interact with aliasing information, allowing both the precision and the efficiency of the sharing analysis of logic programs to be improved. In this ...
详细信息
It is well known that freeness and linearity information positively interact with aliasing information, allowing both the precision and the efficiency of the sharing analysis of logic programs to be improved. In this paper, we present a novel combination of set-sharing with freeness and linearity information, which is characterized by an improved abstract unification operator. We provide a new abstraction function and prove the correctness of the analysis for both the finite tree and the rational tree cases. Moreover, we show that the same notion of redundant information as identified in Bagnara et al. (2000) and Zaffanella et al. (2002) also applies to this abstract domain combination: this allows for the implementation of an abstract unification operator running in polynomial time and achieving the same precision on all the considered observable properties.
The overall goal of this paper is to investigate the theoretical foundations of algorithmic verification techniques for first order linear logic specifications. The fragment of linear logic we consider in this paper i...
详细信息
The overall goal of this paper is to investigate the theoretical foundations of algorithmic verification techniques for first order linear logic specifications. The fragment of linear logic we consider in this paper is based on the linear logicprogramming language called LO (Andreoli and Pareschi, 1990) enriched with universally quantified goal formulas. Although LO was originally introduced as a theoretical foundation for extensions of logicprogramming languages, it can also be viewed as a very general language to specify a wide range of infinite-state concurrent systems (Andreoli, 1992;Cervesato, 1995). Our approach is based on the relation between backward reachability and provability highlighted in our previous work on propositional LO programs (Bozzano et al., 2002). Following this line of research, we define here a general framework for the bottom-up evaluation of first order linear logic specifications. The evaluation procedure is based on an effective fixpoint operator working on a symbolic representation of infinite collections of first order linear logic formulas. The theory of well quasi-orderings (Abdulla et al., 1996;Finkel and Schnoebelen, 2001) can be used to provide sufficient conditions for the termination of the evaluation of non trivial fragments of first order linear logic.
An intermediate-level specification formalism (i.e., specification language supported by laws and a semantic model), LOGS, is presented for PRAM and BSP styles of parallel programming. It extends pre-post sequential s...
详细信息
An intermediate-level specification formalism (i.e., specification language supported by laws and a semantic model), LOGS, is presented for PRAM and BSP styles of parallel programming. It extends pre-post sequential semantics to reveal states at points of global synchronization. The result is an integration of the pre-post and reactive-process styles of specification. The language consists of only six commands from which other useful commands can be derived. Parallel composition is simply logical conjunction and hence compositional. A simple predicative semantics and a complete set of algebraic laws are presented. Novel ingredients include the separation, in our reactive context, of the processes for nontermination and for abortion which coincide in standard programming models;the use of partitions, combining the terminating behavior of one program with the nonterminating behavior of another;and a fixpoint operator, the partitioned fixpoint. Our semantics benefits from the recent "healthiness function" approach for predicative semantics. Use of LOGS, along with the laws for reasoning about it, is demonstrated on two problems: matrix multiplication ( a terminating numerical computation) and the dining philosophers (a reactive computation). The style of reasoning is so close to programmingpractice that direct transformation from LOGS specifications to real PRAM and BSP programs becomes possible.
We propose an alternative way to represent graphs via OBDDs based on the observation that a partition of the graph nodes allows sharing among the employed OBDDs. In the second part of the paper we present a method to ...
详细信息
We propose an alternative way to represent graphs via OBDDs based on the observation that a partition of the graph nodes allows sharing among the employed OBDDs. In the second part of the paper we present a method to compute at the same time the quotient w.r.t. the maximum bisimulation and the OBDD representation of a given graph. The proposed computation is based on an OBDD-rewriting of the notion of Ackermann encoding of hereditarily finite sets into natural numbers.
We propose an alternative way to represent graphs via OBDDs based on the observation that a partition of the graph nodes allows sharing among the employed OBDDs. In the second part of the paper we present a method to ...
详细信息
We propose an alternative way to represent graphs via OBDDs based on the observation that a partition of the graph nodes allows sharing among the employed OBDDs. In the second part of the paper we present a method to compute at the same time the quotient w.r.t. the maximum bisimulation and the OBDD representation of a given graph. The proposed computation is based on an OBDD-rewriting of the notion of Ackermann encoding of hereditarily finite sets into natural numbers.
暂无评论