Effective Marking Equivalence Checking in Systems with Dynamic Process Creation

Abstract

The starting point of this work is a framework allowing to model systems with dynamic process creation, equipped with a procedure to detect symmetric executions (ie., which differ only by the identities of processes). This allows to reduce the state space, potentially to an exponentially smaller size, and, because process identifiers are never reused, this also allows to reduce to finite size some infinite state spaces. However, in this approach, the procedure to detect symmetries does not allow for computationally efficient algorithms, mainly because each newly computed state has to be compared with every already reached state. In this paper, we propose a new approach to detect symmetries in this framework that will solve this problem, thus enabling for efficient algorithms. We formalise a canonical representation of states and identify a sufficient condition on the analysed model that guarantees that every symmetry can be detected. For the models that do not fall into this category, our approach is still correct but does not guarantee a maximal reduction of state space

Formal Modelling and Analysis of Distributed Storage Systems

“…To cope with this, we shall consider symbolic techniques to reduce the cost of model-checking on models in our framework. In particular, symmetries reductions on keys like in [5] and finite abstraction of values on infinite domain like in [2] should be easy to adapt to our case and would allow to consider realistic storage sizes. Combining both is a more challenging problem that we would like to address on the long term.…”

“…Our implementation makes use a feature of the SNAKES framework: dynamic process identifiers. This feature has initially been created to handle systems that can dynamically start/stop processes, see [9,5]. We use here the same notations has in these papers to create requests handlers while being able to record by which node each was created: each node is identified by me that is implemented as a pid (process identifier); given a pid p, ν(p) creates a new pid that has a parent-child relation with p, and χ(p) destroys pid p from the system.…”

SNAKES: A Flexible High-Level Petri Nets Library (Tool Paper)

“…As explained already, it is very hard to have a clear picture of who is using snakes because it is freely available and very few users actually ask for support. Fortunately, there are works we known well about [6,7,12,14,15,21,29,30] and that illustrate typical use cases for snakes as listed below.…”

“…A prototype implementation of a massively parallel ctl* model-checking algorithm for abcd models of security protocols allowed to assess scalability [15]. A new approach to process-symmetry reductions initially defined in [20] has been prototyped in Neco by generating Python code, showing a dramatic performance boost [12], and can be now ported to Cython.…”