  Modern distributed systems include a class of applications in which
non-functional requirements are important. In particular, these applications
include multimedia facilities where real time constraints are crucial to their
correct functioning. In order to specify such systems it is necessary to
describe that events occur at times given by probability distributions and
stochastic automata have emerged as a useful technique by which such systems
can be specified and verified.
  However, stochastic descriptions are very general, in particular they allow
the use of general probability distribution functions, and therefore their
verification can be complex. In the last few years, model checking has emerged
as a useful verification tool for large systems.
  In this paper we describe two model checking algorithms for stochastic
automata. These algorithms consider how properties written in a simple
probabilistic real-time logic can be checked against a given stochastic
automaton.
