Summary: Verication of Probabilistic Systems with Faulty
Parosh Aziz Abdulla 1 and Alexander Rabinovich 2
1 Uppsala University, Sweden
2 Tel Aviv University, Israel
Abstract. Many protocols are designed to operate correctly even in the
case where the underlying communication medium is faulty. To capture
the behaviour of such protocols, lossy channel systems (LCS) [AJ96b]
have been proposed. In an LCS the communication channels are modelled
as FIFO buers which are unbounded, but also unreliable in the sense
that they can nondeterministically lose messages.
Recently, several attempts [BE99,ABIJ00] have been made to study prob-
abilistic Lossy Channel Systems (PLCS) in which the probability of los-
ing messages is taken into account. In this paper, we consider a variant
of PLCS which is more realistic than those studied in [BE99,ABIJ00].
More precisely, we assume that during each step in the execution of the
system, each message may be lost with a certain predened probability.
We show that for such systems the following model checking problem
is decidable: to verify whether a given property denable by nite state
!-automata holds with probability one. We also consider other types of