1,012 research outputs found
A Labelled Analytic Theorem Proving Environment for Categorial Grammar
We present a system for the investigation of computational properties of
categorial grammar parsing based on a labelled analytic tableaux theorem
prover. This proof method allows us to take a modular approach, in which the
basic grammar can be kept constant, while a range of categorial calculi can be
captured by assigning different properties to the labelling algebra. The
theorem proving strategy is particularly well suited to the treatment of
categorial grammar, because it allows us to distribute the computational cost
between the algorithm which deals with the grammatical types and the algebraic
checker which constrains the derivation.Comment: 11 pages, LaTeX2e, uses examples.sty and a4wide.st
Towards Certified Model Checking for PLTL using One-pass Tableaux
The standard model checking setup analyses whether the given system specification satisfies a dedicated temporal property of the system, providing a positive answer here or a counter-example. At the same time, it is often useful to have an explicit proof that certifies the satisfiability. This is exactly what the {\it certified model checking (CMC)} has been introduced for. The paper argues that one-pass (context-based) tableau for PLTL can be efficiently used in the CMC setting, emphasising the following two advantages of this technique. First, the use of the context in which the eventualities occur, forces them to fulfil as soon as possible. Second, a dual to the tableau sequent calculus can be used to formalise the certificates. The combination of the one-pass tableau and the dual sequent calculus enables us to provide not only counter-examples for unsatisfied properties, but also proofs for satisfied properties that can be checked in a proof assistant.
In addition, the construction of the tableau is enriched by an embedded solver, to which we dedicate those (propositional) computational tasks that are costly for the tableaux rules applied solely. The combination of the above techniques is particularly helpful to reason about large (system) specifications
Efficient CTL Verification via Horn Constraints Solving
The use of temporal logics has long been recognised as a fundamental approach
to the formal specification and verification of reactive systems. In this
paper, we take on the problem of automatically verifying a temporal property,
given by a CTL formula, for a given (possibly infinite-state) program. We
propose a method based on encoding the problem as a set of Horn constraints.
The method takes a program, modeled as a transition system, and a property
given by a CTL formula as input. It first generates a set of forall-exists
quantified Horn constraints and well-foundedness constraints by exploiting the
syntactic structure of the CTL formula. Then, the generated set of constraints
are solved by applying an off-the-shelf Horn constraints solving engine. The
program is said to satisfy the property if and only if the generated set of
constraints has a solution. We demonstrate the practical promises of the method
by applying it on a set of challenging examples. Although our method is based
on a generic Horn constraint solving engine, it is able to outperform
state-of-art methods specialised for CTL verification.Comment: In Proceedings HCVS2016, arXiv:1607.0403
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