Jeroen Meijer

Read, Write and Copy Dependencies for Symbolic Model Checking

This paper aims at improving symbolic model checking for explicit state modeling languages, e.g., Promela, Dve and mCRL2. The modular Pins architecture of LTSmin supports a notion of event locality, by merely indicating for each event on which variables it depends. However, one could distinguish four separate dependencies: read, may-write, must-write and copy. In this paper, we introduce these notions in a language-independent manner. In particular, models with arrays need to distinguish overwriting and copying of values.

Property-Preserving Generation of Tailored Benchmark Petri Nets

Bottleneck of the validation and evaluation of analysis and verification tools for distributed systems is the shortage of benchmark problems. Specifically designed benchmark problems are typically artificial, rare, and small, and it is difficult to guarantee challenging properties of realistic benchmarks. This paper shows how to systematically construct arbitrarily complex Petri Nets with guaranteed safety properties. Key to our construction is a top-down parallel decomposition based on lightweight assumption commitment specifications. We will illustrate how a specific strategy for design choices, which may well be automated, leads to benchmarks that grow exponentially with the number of its parallel components, and that are very difficult to verify. In particular, we will report numbers from a systematic sequence of concrete corresponding verification attempts using todays leading verification technology.

Symbolic Reachability Analysis of B Through ProB and LTSmin

We present a symbolic reachability analysis approach for B that can provide a significant speedup over traditional explicit state model checking. The symbolic analysis is implemented by linking ProB to LTSmin, a high-performance language independent model checker. The link is achieved via LTSmin s Pins interface, allowing ProB to benefit from LTSmin s analysis algorithms, while only writing a few hundred lines of glue-code, along with a bridge between ProB and C using OMQ. ProB supports model checking of several formal specification languages such as B, Event-B, Z and

Sound Black-Box Checking in the LearnLib

{\textsc {Tla}}^{+}

LTSmin: High-Performance Language-Independent Model Checking

TLA+. Our experiments are based on a wide variety of B-Method and Event-B models to demonstrate the efficiency of the new link. Among the tested categories are state space generation and deadlock detection; but action detection and invariant checking are also feasible in principle. In many cases we observe speedups of several orders of magnitude. We also compare the results with other approaches for improving model checking, such as partial order reduction or symmetry reduction. We thus provide a new scalable, symbolic analysis algorithm for the B-Method and Event-B, along with a platform to integrate other model checking improvements via LTSmin in the future.

Bandwidth and Wavefront Reduction for Static Variable Ordering in Symbolic Reachability Analysis

RERS is an annual verification challenge that focuses on LTL and reachability properties of reactive systems. In 2017, RERS was extended to a one day workshop that in addition to the original challenge program also featured an invited talk about possible future developments. As a satellite of ISSTA and SPIN, the 2017 RERS Challenge itself increased emphasis on the parallel benchmark problems which, like their sequential counterparts, were generated using property-preserving transformations in order to scale their level of difficulty. The first half of the RERS workshop focused on the 2017 benchmark profiles, the evaluation of the received contributions, and short presentations of each participating team. The second half comprised discussions about attractive problem scenarios for future benchmarks, like race detection, the topic of the invited talk, and about systematic ways to leverage a tools performance based on competition benchmarks and machine learning.

Bandwidth and Wavefront Reduction for Static Variable Ordering in Symbolic Model Checking

In Black-Box Checking (BBC) incremental hypotheses of a system are learned in the form of finite automata. On these automata LTL formulae are verified, or their counterexamples validated on the actual system. We extend the LearnLib’s system-under-learning API for sound BBC, by means of state equivalence, that contrasts the original proposal where an upper-bound on the number of states in the system is assumed. We will show how LearnLib’s new BBC algorithms can be used in practice, as well as how one could experiment with different model checkers and BBC algorithms. Using the RERS 2017 challenge we provide experimental results on the performance of all LearnLib’s active learning algorithms when applied in a BBC setting. The performance of learning algorithms was unknown for this setting. We will show that the novel incremental algorithms TTT, and ADT perform the best.

Improving Reachability Analysis in Ltsmin

Regression testing is an important activity to prevent the introduction of regressions into software updates. Learn-based testing can be used to automatically check new versions of a system for regressions on a system level. This is done by learning a model of the system and model checking this model for system property violations.