Conference
Computer Science Logic
About: Computer Science Logic is an academic conference. The conference publishes majorly in the area(s): Decidability & Mathematical proof. Over the lifetime, 1267 publications have been published by the conference receiving 24095 citations.
Papers published on a yearly basis
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21 Aug 2000
TL;DR: In the ambient logic of classical second order propositional calculus, the specification problem for a family of excluded middle like tautologies is solved and these are shown to be realized by sequential simulations of specific communication schemes for which they provide a safe typing mechanism.
Abstract: In the ambient logic of classical second order propositional calculus, we solve the specification problem for a family of excluded middle like tautologies. These are shown to be realized by sequential simulations of specific communication schemes for which they provide a safe typing mechanism.
1,119 citations
24 Aug 1998
TL;DR: It is proved that computational adequacy holds if and only if the topos is 1-consistent (i.e. its internal logic validates only true Σ\(^{\rm 0}_{\rm 1}\)-sentences).
Abstract: We place simple axioms on an elementary topos which suffice for it to provide a denotational model of call-by-value PCF with sum and product types. The model is synthetic in the sense that types are interpreted by their set-theoretic counterparts within the topos. The main result characterises when the model is computationally adequate with respect to the operational semantics of the programming language. We prove that computational adequacy holds if and only if the topos is 1-consistent (i.e. its internal logic validates only true Σ\(^{\rm 0}_{\rm 1}\)-sentences).
1,000 citations
10 Sep 2001
TL;DR: An extension of Hoare's logic for reasoning about programs that alter data structures is described, based on a possible worlds model of the logic of bunched implications, and includes spatial conjunction and implication connectives alongside those of classical logic.
Abstract: We describe an extension of Hoare's logic for reasoning about programs that alter data structures. We consider a low-level storage model based on a heap with associated lookup, update, allocation and deallocation operations, and unrestricted address arithmetic. The assertion language is based on a possible worlds model of the logic of bunched implications, and includes spatial conjunction and implication connectives alongside those of classical logic. Heap operations are axiomatized using what we call the "small axioms", each of which mentions only those cells accessed by a particular command. Through these and a number of examples we show that the formalism supports local reasoning: A specification and proof can concentrate on only those cells in memory that a program accesses.
This paper builds on earlier work by Burstall, Reynolds, Ishtiaq and O'Hearn on reasoning about data structures.
747 citations
08 Jun 2004
TL;DR: A metric is studied between labelled Markov processes that has the property that processes are at zero distance if and only if they are bisimilar and is related, in spirit, to the Hutchinson metric.
Abstract: The notion of process equivalence of probabilistic processes is sensitive to the exact probabilities of transitions. Thus, a slight change in the transition probabilities will result in two equivalent processes being deemed no longer equivalent. This instability is due to the quantitative nature of probabilistic processes. In a situation where the process behavior has a quantitative aspect there should be a more robust approach to process equivalence. This paper studies a metric between labelled Markov processes. This metric has the property that processes are at zero distance if and only if they are bisimilar. The metric is inspired by earlier work on logics for characterizing bisimulation and is related, in spirit, to the Hutchinson metric.
364 citations
08 Jun 2004
TL;DR: An algorithm to solve the optimal-reachability problem for weighted timed automata that takes time exponential in O(n), where n is the number of clocks, |δ(A)| is the size of the clock constraints and |W max | is thesize of the largest weight.
Abstract: We consider the optimal-reachability problem for a timed automaton with respect to a linear cost function which results in a weighted timed automaton. Our solution to this optimization problem consists of reducing it to computing (parametric) shortest paths in a finite weighted directed graph. We call this graph a parametric sub-region graph. It refines the region graph, a standard tool for the analysis of timed automata, by adding the information which is relevant to solving the optimal-teachability problem. We present an algorithm to solve the optimal-reachability problem for weighted timed automata that takes time exponential in O(n(|δ(A)| + |W max |)), where n is the number of clocks, |δ(A)| is the size of the clock constraints and |W max | is the size of the largest weight. We show that this algorithm can be improved, if we restrict to weighted timed automata with a single clock. In case we consider a single starting state for the optimal-reachability problem, our approach yields an algorithm that takes exponential time only in the length of clock constraints.
285 citations