This paper describes an approach for constructing consistent observers
for dynamic systems based on a formalism of nondeterministic event mo
deling (NEM). The first part of this paper establishes the definitions
of NEM with a main focus on the notion of entropy that is extended fo
r measuring the amount of information from nondeterministic events. Th
e paper demonstrates the importance of the proposed entropy measure in
contrast to the classical uncertainty measure when used in dynamic sy
stems. The importance of the information measure stems from a potentia
l failure of the classical uncertainty when observing nondeterministic
events. Similar problems, which we describe as unobservable states, a
re often seen in dynamic systems where an uncertainty measure is used
in conjunction with some arbitrary decision process. Based on well-def
ined dynamic systems concepts, the second part of the paper formulates
the notion of consistent observer for nondeterministic event modeling
. The consistent observer utilizes the monotonically decreasing entrop
y function of nondeterministic events. An example will be given in thi
s paper which numerically illustrates the notions of:NEM and consisten
t observer.