8,075 research outputs found
A tableau method for the realizability and synthesis of reactive safety specifications
Reactive systems are systems that continuously interact with the environment. In general, as they are critical systems, a failure or malfunction can result in serious consequences, such as loss of human lives or large economic investments. Therefore, correctly modeling the behavior and verification of the system is crucial and, for this, Linear-time Temporal Logic (LTL) and Realizabilty and Synthesis problem represent a promising approach for obtaining confidence in the correctness of a reactive system. The Realizability and Synthesis problem decides if there is a model that satisfies the given specification under all possible environmental behaviours. Moreover, it can be seen as a game between two players; the player who controls the inputs of the system to be synthesized (environment player) and the player who controls the outputs and tries to satisfy the specification for each environmental behaviour (system player).
In this Master thesis, we present both a tableau decision method for deciding the realizability of specifications expressed in a safety fragment of LTL and a prototype that builds a Realizability Tableau from a safety specification input. The prototype returns an open tableau (meaning the specification is realizable) or a closed tableau (when the specification is unrealizable). Finally, we present the future of the work and some of the improvements that will be implemented
Towards an Effective Decision Procedure for LTL formulas with Constraints
This paper presents an ongoing work that is part of a more wide-ranging
project whose final scope is to define a method to validate LTL formulas w.r.t.
a program written in the timed concurrent constraint language tccp, which is a
logic concurrent constraint language based on the concurrent constraint
paradigm of Saraswat. Some inherent notions to tccp processes are
non-determinism, dealing with partial information in states and the monotonic
evolution of the information. In order to check an LTL property for a process,
our approach is based on the abstract diagnosis technique. The concluding step
of this technique needs to check the validity of an LTL formula (with
constraints) in an effective way.
In this paper, we present a decision method for the validity of temporal
logic formulas (with constraints) built by our abstract diagnosis technique.Comment: Part of WLPE 2013 proceedings (arXiv:1308.2055
Reducing Validity in Epistemic ATL to Validity in Epistemic CTL
We propose a validity preserving translation from a subset of epistemic
Alternating-time Temporal Logic (ATL) to epistemic Computation Tree Logic
(CTL). The considered subset of epistemic ATL is known to have the finite model
property and decidable model-checking. This entails the decidability of
validity but the implied algorithm is unfeasible. Reducing the validity problem
to that in a corresponding system of CTL makes the techniques for automated
deduction for that logic available for the handling of the apparently more
complex system of ATL.Comment: In Proceedings SR 2013, arXiv:1303.007
A History of Until
Until is a notoriously difficult temporal operator as it is both existential
and universal at the same time: A until B holds at the current time instant w
iff either B holds at w or there exists a time instant w' in the future at
which B holds and such that A holds in all the time instants between the
current one and w'. This "ambivalent" nature poses a significant challenge when
attempting to give deduction rules for until. In this paper, in contrast, we
make explicit this duality of until to provide well-behaved natural deduction
rules for linear-time logics by introducing a new temporal operator that allows
us to formalize the "history" of until, i.e., the "internal" universal
quantification over the time instants between the current one and w'. This
approach provides the basis for formalizing deduction systems for temporal
logics endowed with the until operator. For concreteness, we give here a
labeled natural deduction system for a linear-time logic endowed with the new
operator and show that, via a proper translation, such a system is also sound
and complete with respect to the linear temporal logic LTL with until.Comment: 24 pages, full version of paper at Methods for Modalities 2009
(M4M-6
SAT-based Explicit LTL Reasoning
We present here a new explicit reasoning framework for linear temporal logic
(LTL), which is built on top of propositional satisfiability (SAT) solving. As
a proof-of-concept of this framework, we describe a new LTL satisfiability
tool, Aalta\_v2.0, which is built on top of the MiniSAT SAT solver. We test the
effectiveness of this approach by demonnstrating that Aalta\_v2.0 significantly
outperforms all existing LTL satisfiability solvers. Furthermore, we show that
the framework can be extended from propositional LTL to assertional LTL (where
we allow theory atoms), by replacing MiniSAT with the Z3 SMT solver, and
demonstrating that this can yield an exponential improvement in performance
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