Showing papers presented at "International Symposium on Theoretical Aspects of Computer Software in 2003"
01 Nov 2003
TL;DR: A logic that can express properties of freshness, secrecy, structure, and behavior of concurrent systems is presented, which includes spatial operations corresponding to composition, local name restriction, and a primitive fresh name quantifier.
Abstract: We present a logic that can express properties of freshness, secrecy, structure, and behavior of concurrent systems. In addition to standard logical and temporal operators, our logic includes spatial operations corresponding to composition, local name restriction, and a primitive fresh name quantifier. Properties can also be defined by recursion; a central aim of this paper is then the combination of a logical notion of freshness with inductive and coinductive definitions of properties.
274 citations
01 Nov 2003
TL;DR: Automata theoretic methods are applied to characterize the problem equivalently by using regular expressions and word equations to induces new results on non-structural subtype entailment, constitutes a promising starting point for further investigations on decidability.
Abstract: Decidability of non-structural subtype entailment is a long-standing open problem in programming language theory In this paper, we apply automata theoretic methods to characterize the problem equivalently by using regular expressions and word equations. This characterization induces new results on non-structural subtype entailment, constitutes a promising starting point for further investigations on decidability, and explains for the first time why the problem is so difficult. The difficulty is caused by implicit word equations that we make explicit.
7 citations
01 Nov 2003
TL;DR: A type theory with infinitary intersection and union types for an extension of the λ-calculus is introduced and it is proved soundness and completeness are achieved using a generalization of Abramsky's finitary logic of domains.
Abstract: A type theory with infinitary intersection and union types for an extension of the λ-calculus is introduced. Types are viewed as upper closed subsets of a Scott domain and intersection and union type constructors are interpreted as the set-theoretic intersection and union, respectively, even when they are not finite. The assignment of types to λ-terms extends naturally the basic type assignment system. We prove soundness and completeness using a generalization of Abramsky's finitary logic of domains. Finally we apply the framework to applicative transition systems, obtaining a sound a complete infinitary intersection type assignment system for the lazy λ-calculus.
3 citations
01 Nov 2003
TL;DR: This paper demonstrates the generation of a linear-time query-answering algorithm based on the constructive proof of Higman's lemma, which solves the target problem of a fixed disjunctive monadic query on an indefinite database over linearly ordered domains.
Abstract: This paper demonstrates the generation of a linear-time query-answering algorithm based on the constructive proof of Higman's lemma by Murthy and Russell [Proceedings of the 5th IEEE Symposium on Logic in Computer Science, 1990, p. 257-267]. The target problem is linear-time evaluation of a fixed disjunctive monadic query on an indefinite database over linearly ordered domains, first posed by van der Meyden [Proceedings of the 11th ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, 1992, p. 331-345]. Van der Meyden showed the existence of a linear-time algorithm, but an explicit construction has, until now, not been reported.
1 citations