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We present a logic and logic programming based approach for analysing event-based requirements specifications given in terms of a system’s reaction to events and safety properties. The approach uses a variant of Kowalski and Sergot’s Event Calculus to represent such specifications declaratively and an abductive reasoning mechanism for analysing safety properties. Given a system description and a safety...
The HAL language includes a Herbrand constraint solver which uses Taylor’s PARMA scheme rather than the standard WAM representation. This allows HAL to generate more efficient Mercury code. Unfortunately, PARMA’s variable representation requires value trailing with a trail stack consumption about twice as large as for the WAM. We present a trailing analysis aimed at determining which Herbrand variables...
We show how logic programs may be used to protect deductive databases from the unauthorized retrieval of positive and negative information, and from unauthorized insert and delete requests. To achieve this protection, a deductive database is expressed in a form that is guaranteed to permit only authorized access requests to be performed. The protection of the positive information that may be retrieved...
We present a CLP-based approach to reasoning about actions in the presence of incomplete states. Constraints expressing negative and disjunctive state knowledge are processed by a set of special Constraint Handling Rules. In turn, these rules reduce to standard finite domain constraints when handling variable arguments of single state components. Correctness of the approach is proved against the general...
Systems biology is a new area in biology that aims at achieving a systems-level understanding of biological systems. While current genome projects provide a huge amount of data on genes or proteins, lots of research is still necessary to understand how the different parts of a biological system interact in order to perform complex biological functions. Computational models that help to analyze, explain...
Logic programming based tools for real-time model checking are beginning to emerge. In a previous work we had demonstrated the feasibility of building such a model checker by combining constraint processing and tabulation. But efficiency and practicality of such a model checker were not adequately addressed. In this paper we describe XMC/dbm, an efficient model checker for real-time systems using...
Forward analysis procedures for infinite-state systems such as timed systems were limited to safety properties. We give the first constraint-based forward analysis for infinite-state systems that goes beyond safety properties. Namely, we take the restriction of the μ-calculus to least-fixpoint formulas where negation is applied to closed subformulas only. We characterize these properties as perfect...
The impetus for our current research is the need to provide an adequate framework for belief reasoning in multi-level secure (MLS) databases. We demonstrate that a prudent application of the concept of inheritance in a deductive database setting will help capture the notion of declarative belief and belief reasoning in MLS databases in an elegant way. In this paper, we show that these concepts can...
We develop a framework for addressing correctness and time-liness-of-propagation issues for reactive constraints — global constraints or user-defined constraints that are implemented through constraint propagation. The notion of propagation completeness is introduced to capture timeliness of constraint propagation. A generalized form of arc-consistency is formulated which unifies many local consistency...
Region-based memory management is an attractive alternative to garbage collection. It relies on a compile-time analysis to annotate the program with explicit allocation and deallocation instructions, where lifetimes of memory objects are grouped together in regions. This paper investigates how to adapt the runtime part of region-based memory management to the WAM setting. We present additions to the...
A non-algorithmic approach to garbage collection for the WAM heap is developed. A set of garbage collections compatible with the WAM is specified in two steps: the first step makes the useful data for each continuation private and ensures that only useful terms survive garbage collection. The second step completes garbage collection by extending the intuitive notion of folding of identical structures...
Garbage collection by copying is becoming more and more popular for Prolog. Copying requires a marking phase in order to be safe: safeness means that the to-space is guaranteed not to overflow. However, some systems use a copying garbage collector without marking prior to copying, and instead postpone the copying of potentially unsafe cells. Such systems only collect small portions of the heap and...
It is widely accepted that many algorithms can be concisely and clearly expressed as logical inference rules. However, logic programming has been inappropriate for the study of the running time of algorithms because there has not been a clear and precise model of the run time of a logic program. We present a logic programming model of computation appropriate for the study of the run time of a wide...
We present a concrete proposal for enhancing Prolog and Prolog based Constraint Logic Programming languages with a new language construct, the logical loop. This is a shorthand notation for the most commonly used recursive control structure: the iteration or tail recursion. We argue that this enhancement fits well with the existing language concepts, enhances productivity and maintainability, and...
Deduction and induction are unified on the basis of a generalized notion of logical consequence, having classical first-order logic as a particular case. RichProlog is a natural extension of Prolog rooted in this generalized logic, in the same way as Prolog is rooted in classical logic. Prolog can answer Σ1 queries as a side effect of a deductive inference. RichProlog can answer Σ ...
The growing importance of XML as a data interchange standard demands languages for data querying and transformation. Since the mid 90es, several such languages have been proposed that are inspired from functional languages (such as XSLT [1]) and/or database query languages (such as XQuery [2]). This paper addresses applying logic programming concepts and techniques to designing a declarative, rule-based...
Higher-order logic programming languages such as Elf extend first-order logic programming in two ways: first-order terms are replaced with (dependently) typed λ-terms and the body of clauses may contain implication and universal quantification. In this paper, we describe tabled higher-order logic programming where some redundant computation is eliminated by memoizing sub-computation and re-using its...
This paper presents two proof systems for the equivalence of programs. The language concerned is CLP to which the universal quantifier is added (CLP∀). Both systems are based on first order classical logic. The first uses an induction rule and allows one to prove that the set of finite successes of a program is included in another program’s corresponding set. The second uses a coinduction rule...
A strict correspondence between the proof-search space of a logical formal system and computations in a simple process algebra is established. Sequential composition in the process algebra corresponds to a logical relation in the formal system in this sense our approach is purely logical, no axioms or encodings are involved. The process algebra is a minimal restriction of CCS to parallel and sequential...
Abductive logic programming has been widely used to declaratively specify a variety of problems in AI including updates in data and knowledge bases, belief revision, diagnosis, causal theory, and default reasoning. One of the most significant issues in abductive logic programming is to develop a reasonable method for knowledge assimilation, which incorporates obtained explanations into the current...
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