867 research outputs found
Parameterized Communicating Automata: Complementation and Model Checking
We study the language-theoretical aspects of parameterized communicating automata (PCAs), in which processes communicate via rendez-vous. A given PCA can be run on any topology of bounded degree such as pipelines, rings, ranked trees, and grids. We show that, under a context bound, which restricts the local behavior of each process, PCAs are effectively complementable. Complementability is considered a key aspect of robust automata models and can, in particular, be exploited for verification. In this paper, we use it to obtain a characterization of context-bounded PCAs in terms of monadic second-order (MSO) logic. As the emptiness problem for context-bounded PCAs is decidable for the classes of pipelines, rings, and trees, their model-checking problem wrt. MSO properties also becomes decidable. While previous work on model checking parameterized systems typically uses temporal logics without next operator, our MSO logic allows one to express several natural next modalities
Parameterized Synthesis
We study the synthesis problem for distributed architectures with a
parametric number of finite-state components. Parameterized specifications
arise naturally in a synthesis setting, but thus far it was unclear how to
detect realizability and how to perform synthesis in a parameterized setting.
Using a classical result from verification, we show that for a class of
specifications in indexed LTL\X, parameterized synthesis in token ring networks
is equivalent to distributed synthesis in a network consisting of a few copies
of a single process. Adapting a well-known result from distributed synthesis,
we show that the latter problem is undecidable. We describe a semi-decision
procedure for the parameterized synthesis problem in token rings, based on
bounded synthesis. We extend the approach to parameterized synthesis in
token-passing networks with arbitrary topologies, and show applicability on a
simple case study. Finally, we sketch a general framework for parameterized
synthesis based on cutoffs and other parameterized verification techniques.Comment: Extended version of TACAS 2012 paper, 29 page
Using SPIN to Analyse the Tree Identification Phase of the IEEE 1394 High-Performance Serial Bus(FireWire)Protocol
We describe how the tree identification phase of the IEEE 1394 high-performance serial bus (FireWire) protocol is modelled in Promela and verified using SPIN. The verification of arbitrary system configurations is discussed
Mechanizing a Process Algebra for Network Protocols
This paper presents the mechanization of a process algebra for Mobile Ad hoc
Networks and Wireless Mesh Networks, and the development of a compositional
framework for proving invariant properties. Mechanizing the core process
algebra in Isabelle/HOL is relatively standard, but its layered structure
necessitates special treatment. The control states of reactive processes, such
as nodes in a network, are modelled by terms of the process algebra. We propose
a technique based on these terms to streamline proofs of inductive invariance.
This is not sufficient, however, to state and prove invariants that relate
states across multiple processes (entire networks). To this end, we propose a
novel compositional technique for lifting global invariants stated at the level
of individual nodes to networks of nodes.Comment: This paper is an extended version of arXiv:1407.3519. The
Isabelle/HOL source files, and a full proof document, are available in the
Archive of Formal Proofs, at http://afp.sourceforge.net/entries/AWN.shtm
Automata and Logics for Concurrent Systems: Realizability and Verification
Automata are a popular tool to make computer systems accessible to formal methods. While classical finite automata are suitable to model sequential boolean programs, models of concurrent systems involve several interacting processes and extend finite-state machines in various respects. This habilitation thesis surveys several such extensions, including pushdown automata with multiple stacks, communicating automata with fixed, parameterized, or dynamic communication topology, and automata running on words over infinite alphabets. We focus on two major questions of classical automata theory, namely realizability (asking whether a specification has an automata counterpart) and model checking (asking whether a given automaton satisfies its specification)
Future-based Static Analysis of Message Passing Programs
Message passing is widely used in industry to develop programs consisting of
several distributed communicating components. Developing functionally correct
message passing software is very challenging due to the concurrent nature of
message exchanges. Nonetheless, many safety-critical applications rely on the
message passing paradigm, including air traffic control systems and emergency
services, which makes proving their correctness crucial. We focus on the
modular verification of MPI programs by statically verifying concrete Java
code. We use separation logic to reason about local correctness and define
abstractions of the communication protocol in the process algebra used by
mCRL2. We call these abstractions futures as they predict how components will
interact during program execution. We establish a provable link between futures
and program code and analyse the abstract futures via model checking to prove
global correctness. Finally, we verify a leader election protocol to
demonstrate our approach.Comment: In Proceedings PLACES 2016, arXiv:1606.0540
Verification of parameterized communicating automata via split-width
International audienceWe study verification problems for distributed systems communicating via unbounded FIFO channels. The number of processes of the system as well as the communication topology are not fixed a priori. Systems are given by parameterized communicating automata (PCAs) which can be run on any communication topology of bounded degree, with arbitrarily many processes. Such systems are Turing powerful so we concentrate on under-approximate verification. We extend the notion of split-width to behaviors of PCAs. We show that emptiness, reachability and model-checking problems of PCAs are decidable when restricted to behaviors of bounded split-width. Reachability and emptiness are Exptime-complete, but only polynomial in the size of the PCA. We also describe several concrete classes of bounded split-width, for which we prove similar results
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