6,310 research outputs found
Sequentializing Parameterized Programs
We exhibit assertion-preserving (reachability preserving) transformations
from parameterized concurrent shared-memory programs, under a k-round
scheduling of processes, to sequential programs. The salient feature of the
sequential program is that it tracks the local variables of only one thread at
any point, and uses only O(k) copies of shared variables (it does not use extra
counters, not even one counter to keep track of the number of threads).
Sequentialization is achieved using the concept of a linear interface that
captures the effect an unbounded block of processes have on the shared state in
a k-round schedule. Our transformation utilizes linear interfaces to
sequentialize the program, and to ensure the sequential program explores only
reachable states and preserves local invariants.Comment: In Proceedings FIT 2012, arXiv:1207.348
Reachability and Termination Analysis of Concurrent Quantum Programs
We introduce a Markov chain model of concurrent quantum programs. This model
is a quantum generalization of Hart, Sharir and Pnueli's probabilistic
concurrent programs. Some characterizations of the reachable space, uniformly
repeatedly reachable space and termination of a concurrent quantum program are
derived by the analysis of their mathematical structures. Based on these
characterizations, algorithms for computing the reachable space and uniformly
repeatedly reachable space and for deciding the termination are given.Comment: Accepted by Concur'12. Comments are welcom
Petri Games: Synthesis of Distributed Systems with Causal Memory
We present a new multiplayer game model for the interaction and the flow of
information in a distributed system. The players are tokens on a Petri net. As
long as the players move in independent parts of the net, they do not know of
each other; when they synchronize at a joint transition, each player gets
informed of the causal history of the other player. We show that for Petri
games with a single environment player and an arbitrary bounded number of
system players, deciding the existence of a safety strategy for the system
players is EXPTIME-complete.Comment: In Proceedings GandALF 2014, arXiv:1408.556
A Process Calculus for Expressing Finite Place/Transition Petri Nets
We introduce the process calculus Multi-CCS, which extends conservatively CCS
with an operator of strong prefixing able to model atomic sequences of actions
as well as multiparty synchronization. Multi-CCS is equipped with a labeled
transition system semantics, which makes use of a minimal structural
congruence. Multi-CCS is also equipped with an unsafe P/T Petri net semantics
by means of a novel technique. This is the first rich process calculus,
including CCS as a subcalculus, which receives a semantics in terms of unsafe,
labeled P/T nets. The main result of the paper is that a class of Multi-CCS
processes, called finite-net processes, is able to represent all finite
(reduced) P/T nets.Comment: In Proceedings EXPRESS'10, arXiv:1011.601
Liveness of Randomised Parameterised Systems under Arbitrary Schedulers (Technical Report)
We consider the problem of verifying liveness for systems with a finite, but
unbounded, number of processes, commonly known as parameterised systems.
Typical examples of such systems include distributed protocols (e.g. for the
dining philosopher problem). Unlike the case of verifying safety, proving
liveness is still considered extremely challenging, especially in the presence
of randomness in the system. In this paper we consider liveness under arbitrary
(including unfair) schedulers, which is often considered a desirable property
in the literature of self-stabilising systems. We introduce an automatic method
of proving liveness for randomised parameterised systems under arbitrary
schedulers. Viewing liveness as a two-player reachability game (between
Scheduler and Process), our method is a CEGAR approach that synthesises a
progress relation for Process that can be symbolically represented as a
finite-state automaton. The method is incremental and exploits both
Angluin-style L*-learning and SAT-solvers. Our experiments show that our
algorithm is able to prove liveness automatically for well-known randomised
distributed protocols, including Lehmann-Rabin Randomised Dining Philosopher
Protocol and randomised self-stabilising protocols (such as the Israeli-Jalfon
Protocol). To the best of our knowledge, this is the first fully-automatic
method that can prove liveness for randomised protocols.Comment: Full version of CAV'16 pape
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