Summary: Model­checking for Probabilistic Real­time Systems
(Appeared in the Proc. of the 18th ICALP, LNCS 510, 1991)
Rajeev Alur
AT&T Bell Labs
Costas Courcoubetis
University of Crete and FORTH
David L. Dill
Stanford University
Abstract
Model­checking is a method of verifying concurrent systems in which a state­graph model
of the system behavior is compared with a temporal logic formula. This paper extends model­
checking to stochastic real­time systems, whose behavior depends on probabilistic choice and
quantitative time. The specification language is TCTL, a branching­time temporal logic for
expressing real­time properties. We interpret the formulas of the logic over generalized semi­
Markov processes. Our model can express constraints like ``the delay between the request and
the response is distributed uniformly between 2 to 4 seconds''.
We present an algorithm that combines model­checking for real­time non­probabilistic sys­
tems with model­checking for finite­state discrete­time Markov chains. The correctness of the
algorithm is not obvious, because it analyzes the projection of a Markov process onto a finite
state space. The projection process is not Markov, so our most significant result is that the

Source: Alur, Rajeev - Department of Computer and Information Science, University of Pennsylvania

Collections: Computer Technologies and Information Sciences