1,233 research outputs found
Truly On-The-Fly LTL Model Checking
We propose a novel algorithm for automata-based LTL model checking that
interleaves the construction of the generalized B\"{u}chi automaton for the
negation of the formula and the emptiness check. Our algorithm first converts
the LTL formula into a linear weak alternating automaton; configurations of the
alternating automaton correspond to the locations of a generalized B\"{u}chi
automaton, and a variant of Tarjan's algorithm is used to decide the existence
of an accepting run of the product of the transition system and the automaton.
Because we avoid an explicit construction of the B\"{u}chi automaton, our
approach can yield significant improvements in runtime and memory, for large
LTL formulas. The algorithm has been implemented within the SPIN model checker,
and we present experimental results for some benchmark examples
On the decidability and complexity of Metric Temporal Logic over finite words
Metric Temporal Logic (MTL) is a prominent specification formalism for
real-time systems. In this paper, we show that the satisfiability problem for
MTL over finite timed words is decidable, with non-primitive recursive
complexity. We also consider the model-checking problem for MTL: whether all
words accepted by a given Alur-Dill timed automaton satisfy a given MTL
formula. We show that this problem is decidable over finite words. Over
infinite words, we show that model checking the safety fragment of MTL--which
includes invariance and time-bounded response properties--is also decidable.
These results are quite surprising in that they contradict various claims to
the contrary that have appeared in the literature
Quantified CTL: Expressiveness and Complexity
While it was defined long ago, the extension of CTL with quantification over
atomic propositions has never been studied extensively. Considering two
different semantics (depending whether propositional quantification refers to
the Kripke structure or to its unwinding tree), we study its expressiveness
(showing in particular that QCTL coincides with Monadic Second-Order Logic for
both semantics) and characterise the complexity of its model-checking and
satisfiability problems, depending on the number of nested propositional
quantifiers (showing that the structure semantics populates the polynomial
hierarchy while the tree semantics populates the exponential hierarchy)
Monitoring temporal information flow
We present a framework for monitoring information flow in security-critical reactive systems, such as communication protocols, cell phone apps, document servers and web browsers. The secrecy requirements in such systems typically vary over time in response to the interaction with the environment. Standard notions of secrecy, like noninterference, must therefore be extended by specifying precisely when and under what conditions a particular event needs to remain secret. Our framework is based on the temporal logic SecLTL, which combines the standard temporal operators of linear-time temporal logic with the modal Hide operator for the specification of information flow properties. We present a first monitoring algorithm for SecLTL specifications, based on a translation of SecLTL formulas to alternating automata, and identify open research questions and directions for future work
Counting LTL
The original publication is available at ieeexplore.ieee.org.International audienceThis paper presents a quantitative extension for the linear-time temporal logic LTL allowing to specify the number of states satisfying certain sub-formulas along paths. We give decision procedures for the satisfiability and model checking of this new temporal logic and study the complexity of the corresponding problems. Furthermore we show that the problems become undecidable when more expressive constraints are considered
Verifying and Synthesising Multi-Agent Systems against One-Goal Strategy Logic Specifications
© Copyright 2015, Association for the Advancement of Artificial Intelligence (www.aaa1.org). All rights reserved.Strategy Logic (SL) has recently come to the fore as a useful specification language to reason about multi-agent systems. Its one-goal fragment, or SL[1g], is of particular interest as it strictly subsumes widely used logics such as ATL∗, while maintaining attractive complexity features. In this paper we put forward an automata-based methodology for verifying and synthesising multi-agent systems against specifications given in SL[Ig], We show that the algorithm is sound and optimal from a computational point of view. A key feature of the approach is that all data structures and operations on them can be performed on BDDs. We report on a BDD-based model checker implementing the algorithm and evaluate its performance on the fair process scheduler synthesis
Reasoning about Knowledge and Strategies: Epistemic Strategy Logic
In this paper we introduce Epistemic Strategy Logic (ESL), an extension of
Strategy Logic with modal operators for individual knowledge. This enhanced
framework allows us to represent explicitly and to reason about the knowledge
agents have of their own and other agents' strategies. We provide a semantics
to ESL in terms of epistemic concurrent game models, and consider the
corresponding model checking problem. We show that the complexity of model
checking ESL is not worse than (non-epistemic) Strategy LogicComment: In Proceedings SR 2014, arXiv:1404.041
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