A Theory of Distributed Markov Chains

Author(s):  
P.S. Thiagarajan ◽  
Shaofa Yang

We present the theory of distributed Markov chains (DMCs). A DMC consists of a collection of communicating probabilistic agents in which the synchronizations determine the probability distribution for the next moves of the participating agents. The key feature of a DMC is that the synchronizations are deterministic, in the sense that any two simultaneously enabled synchronizations involve disjoint sets of agents. Using our theory of DMCs we show how one can analyze the behavior using the interleaved semantics of the model. A key point is, the transition system which defines the interleaved semantics is—except in degenerate cases—not a Markov chain. Hence one must develop new techniques to analyze these behaviors exhibiting both concurrency and stochasticity. After establishing the core theory we develop a statistical model checking procedure which verifies the dynamical properties of the trajectories generated by the the model. The specifications consist of Boolean combinations of component-wise bounded linear time temporal logic formulas. We also provide a probabilistic Petri net representation of DMCs and use it to derive a probabilistic event structure semantics.

2020 ◽  
Vol 175 (1-4) ◽  
pp. 301-325
Author(s):  
P. S. Thiagarajan ◽  
Shaofa Yang

We present the theory of distributed Markov chains (DMCs). A DMC consists of a collection of communicating probabilistic agents in which the synchronizations determine the probability distribution for the next moves of the participating agents. The key feature of a DMC is that the synchronizations are deterministic, in the sense that any two simultaneously enabled synchronizations involve disjoint sets of agents. Using our theory of DMCs we show how one can analyze the behavior using the interleaved semantics of the model. A key point is, the transition system which defines the interleaved semantics is—except in degenerate cases—not a Markov chain. Hence one must develop new techniques to analyze these behaviors exhibiting both concurrency and stochasticity. After establishing the core theory we develop a statistical model checking procedure which verifies the dynamical properties of the trajectories generated by the the model. The specifications consist of Boolean combinations of component-wise bounded linear time temporal logic formulas. We also provide a probabilistic Petri net representation of DMCs and use it to derive a probabilistic event structure semantics.


2000 ◽  
Vol 3 (2) ◽  
Author(s):  
Vanderlei Moraes Rodrigues ◽  
Flavio Rech Wagner

This paper introduces a formalism named DSYNC aimed at. the design and verification of synchronous concurrent systems. The components of this formalism are a transition system and first-order linear-time temporal logic. The DSYNC transition system adopts a synchronous computation model, includes a method to solve write-conflicts, and represents transitions as possibly non-terminating imperative commands. The conflict resolution method is dynamic because it detects conflicts at run-time. The DSYNC logic allows for formal reasoning about DSYNC transition systems using compositional and modular proofs. Such features are missing in other formalisms based on transition systems and temporal logics, although they are important for the verification of a large class of systems. This paper also discusses some of the pragmatics in verifying systems with DSYNC; and considers some extensions to the formalism. DSYNC is based on hte Hoare logic and the UNITY formalism. 


2021 ◽  
Vol 21 (2) ◽  
pp. 18-32
Author(s):  
Antoine El-Hokayem ◽  
Marius Bozga ◽  
Joseph Sifakis

We study a framework for the specification and validation of dynamic reconfigurable systems. The framework is based on configuration logic for the description of architecture styles which are families of architectures sharing common connectivity features. We express specifications in the Temporal Configuration Logic (TCL), a linear time temporal logic built from atomic formulas characterizing system configurations and temporal modalities. Two non-trivial benchmarks are introduced to show the adequacy of TCL for the specification of dynamic reconfigurable systems. We study an effective model-checking procedure based on SMT techniques for a non-trivial fragment of TCL which has been implemented in a prototype runtime verification tool. We provide preliminary experimental results illustrating the capabilities of the tool on the considered benchmark systems.


2004 ◽  
Vol XXIV (1) ◽  
pp. 17-24 ◽  
Author(s):  
S. Evangelista ◽  
C. Kaiser ◽  
J. F. Pradat-Peyre ◽  
P. Rousseau

Author(s):  
KIAM TIAN SEOW ◽  
MICHEL PASQUIER

This paper proposes a new logical framework for vehicle route-sequence planning of passenger travel requests. Each request is a fetch-and-send service task associated with two request-locations, namely, a source and a destination. The proposed framework is developed using propositional linear time temporal logic of Manna and Pnueli. The novelty lies in the use of the formal language for both the specification and theorem-proving analysis of precedence constraints among the location visits that are inherent in route sequences. In the framework, legal route sequences—each of which visits every request location once and only once in the precedence order of fetch-and-send associated with every such request—is formalized and justified, forming a basis upon which the link between a basic precedence constraint and the corresponding canonical forbidden-state formula is formally established. Over a given base route plan, a simple procedure to generate a feasible subplan based on a specification of the forbidden-state canonical form is also given. An example demonstrates how temporal logic analysis and the proposed procedure can be applied to select a final (feasible) subplan based on additional precedence constraints.


2003 ◽  
Vol 45 (4) ◽  
Author(s):  
Daniel Große ◽  
Rolf Drechsler

ZusammenfassungDer vorgestellte Ansatz ermöglicht es, für SystemC-Schaltkreisbeschreibungen, die über einer gegebenen Gatterbibliothek definiert sind, Eigenschaften zu beweisen (engl. property checking). Als Spezifikationssprache wird LTL (linear time temporal logic) verwendet. Für den Beweis einer LTL-Eigenschaft kann die Erfüllbarkeit einer Booleschen Funktion betrachtet werden, die aus der Eigenschaft und der Schaltkreisbeschreibung mittels symbolischer Methoden konstruiert wird. Im Gegensatz zu simulationsbasierten Ansätzen kann dabei Vollständigkeit gewährleistet werden. Anhand einer Fallstudie eines skalierbaren Arbiters wird die Effizienz des Beweisverfahrens untersucht.


Author(s):  
Alessio Lomuscio ◽  
Edoardo Pirovano

We present a method for reasoning about fault-tolerance in unbounded robotic swarms. We introduce a novel semantics that accounts for the probabilistic nature of both the swarm and possible malfunctions, as well as the unbounded nature of swarm systems. We define and interpret a variant of probabilistic linear-time temporal logic on the resulting executions, including those arising from faulty behaviour by some of the agents in the swarm. We specify the decision problem of parameterised fault-tolerance, which concerns determining whether a probabilistic specification holds under possibly faulty behaviour. We outline a verification procedure that we implement and use to study a foraging protocol from swarm robotics, and report the experimental results obtained.


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