32,403 research outputs found
Slowdown invariance of timed regular expressions
In critical systems, it is frequently essential to know whether the system satisfies a number of real-time constraints, usually specified in a real-time logic such as timed regular expressions. However, after having verified a system correct, changes in its environment may slow it down or speed it up, possibly invalidating the properties. Colombo et al. (1) have presented a theory of slowdown and speedup invariance to determine which specifications are safe with respect to system retiming, and applied the approach to duration calculus. In this paper we build upon their approach, applying it to timed regular expressions. We hence identify a fragment of the logic which is invariant under the speedup or slowdown of a system, enabling more resilient verification of properties written in the logic.peer-reviewe
LNCS
Imprecision in timing can sometimes be beneficial: Metric interval temporal logic (MITL), disabling the expression of punctuality constraints, was shown to translate to timed automata, yielding an elementary decision procedure. We show how this principle extends to other forms of dense-time specification using regular expressions. By providing a clean, automaton-based formal framework for non-punctual languages, we are able to recover and extend several results in timed systems. Metric interval regular expressions (MIRE) are introduced, providing regular expressions with non-singular duration constraints. We obtain that MIRE are expressively complete relative to a class of one-clock timed automata, which can be determinized using additional clocks. Metric interval dynamic logic (MIDL) is then defined using MIRE as temporal modalities. We show that MIDL generalizes known extensions of MITL, while translating to timed automata at comparable cost
Decentralised Runtime Verification of Timed Regular Expressions
Ensuring the correctness of distributed cyber-physical systems can be done at runtime by monitoring properties over their behaviour. In a decentralised setting, such behaviour consists of multiple local traces, each offering an incomplete view of the system events to the local monitors, as opposed to the standard centralised setting with a unique global trace. We introduce the first monitoring framework for timed properties described by timed regular expressions over a distributed network of monitors. First, we define functions to rewrite expressions according to partial knowledge for both the centralised and decentralised cases. Then, we define decentralised algorithms for monitors to evaluate properties using these functions, as well as proofs of soundness and eventual completeness of said algorithms. Finally, we implement and evaluate our framework on synthetic timed regular expressions, giving insights on the cost of the centralised and decentralised settings and when to best use each of them
LNCS
We provide a procedure for detecting the sub-segments of an incrementally observed Boolean signal ω that match a given temporal pattern ϕ. As a pattern specification language, we use timed regular expressions, a formalism well-suited for expressing properties of concurrent asynchronous behaviors embedded in metric time. We construct a timed automaton accepting the timed language denoted by ϕ and modify it slightly for the purpose of matching. We then apply zone-based reachability computation to this automaton while it reads ω, and retrieve all the matching segments from the results. Since the procedure is automaton based, it can be applied to patterns specified by other formalisms such as timed temporal logics reducible to timed automata or directly encoded as timed automata. The procedure has been implemented and its performance on synthetic examples is demonstrated
LNCS
We introduce in this paper AMT 2.0 , a tool for qualitative and quantitative analysis of hybrid continuous and Boolean signals that combine numerical values and discrete events. The evaluation of the signals is based on rich temporal specifications expressed in extended Signal Temporal Logic (xSTL), which integrates Timed Regular Expressions (TRE) within Signal Temporal Logic (STL). The tool features qualitative monitoring (property satisfaction checking), trace diagnostics for explaining and justifying property violations and specification-driven measurement of quantitative features of the signal
Compositional Verification for Timed Systems Based on Automatic Invariant Generation
We propose a method for compositional verification to address the state space
explosion problem inherent to model-checking timed systems with a large number
of components. The main challenge is to obtain pertinent global timing
constraints from the timings in the components alone. To this end, we make use
of auxiliary clocks to automatically generate new invariants which capture the
constraints induced by the synchronisations between components. The method has
been implemented in the RTD-Finder tool and successfully experimented on
several benchmarks
Quantitative Regular Expressions for Arrhythmia Detection Algorithms
Motivated by the problem of verifying the correctness of arrhythmia-detection
algorithms, we present a formalization of these algorithms in the language of
Quantitative Regular Expressions. QREs are a flexible formal language for
specifying complex numerical queries over data streams, with provable runtime
and memory consumption guarantees. The medical-device algorithms of interest
include peak detection (where a peak in a cardiac signal indicates a heartbeat)
and various discriminators, each of which uses a feature of the cardiac signal
to distinguish fatal from non-fatal arrhythmias. Expressing these algorithms'
desired output in current temporal logics, and implementing them via monitor
synthesis, is cumbersome, error-prone, computationally expensive, and sometimes
infeasible.
In contrast, we show that a range of peak detectors (in both the time and
wavelet domains) and various discriminators at the heart of today's
arrhythmia-detection devices are easily expressible in QREs. The fact that one
formalism (QREs) is used to describe the desired end-to-end operation of an
arrhythmia detector opens the way to formal analysis and rigorous testing of
these detectors' correctness and performance. Such analysis could alleviate the
regulatory burden on device developers when modifying their algorithms. The
performance of the peak-detection QREs is demonstrated by running them on real
patient data, on which they yield results on par with those provided by a
cardiologist.Comment: CMSB 2017: 15th Conference on Computational Methods for Systems
Biolog
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