<s>
Analysis	O
of	O
Petri	B-Operating_System
nets	I-Operating_System
can	O
be	O
performed	O
by	O
means	O
of	O
constructing	O
either	O
reachable	O
state	O
spaces	O
(	O
or	O
reachable	O
markings	O
)	O
or	O
via	O
the	O
process	O
of	O
graph-based	O
unfolding	O
.	O
</s>
<s>
The	O
prefix	O
of	O
a	O
Petri	B-Operating_System
net	I-Operating_System
unfolding	O
,	O
which	O
is	O
an	O
acyclic	O
Petri	B-Operating_System
net	I-Operating_System
graph	O
,	O
contains	O
the	O
same	O
information	O
about	O
the	O
properties	O
of	O
the	O
Petri	B-Operating_System
net	I-Operating_System
as	O
the	O
reachability	O
graph	O
,	O
plus	O
it	O
contains	O
information	O
about	O
sequence	O
,	O
concurrency	B-Operating_System
and	O
conflict	O
relations	O
between	O
Petri	B-Operating_System
net	I-Operating_System
transitions	O
and	O
Petri	B-Operating_System
net	I-Operating_System
places	O
.	O
</s>
<s>
The	O
advantages	O
of	O
the	O
use	O
of	O
unfolding	O
in	O
practice	O
are	O
typically	O
associated	O
with	O
the	O
fact	O
that	O
the	O
unfolding	O
prefix	O
is	O
much	O
more	O
compact	O
than	O
the	O
reachability	O
graph	O
of	O
the	O
Petri	B-Operating_System
net	I-Operating_System
being	O
analysed	O
.	O
</s>
<s>
Petri	B-Application
net	I-Application
unfoldings	I-Application
were	O
originally	O
introduced	O
by	O
Ken	O
McMillan	O
.	O
</s>
<s>
There	O
are	O
applications	O
of	O
Petri	B-Application
net	I-Application
unfoldings	I-Application
in	O
the	O
analysis	O
and	O
synthesis	O
of	O
concurrent	B-Operating_System
systems	I-Operating_System
and	O
asynchronous	B-Application
circuits	I-Application
.	O
</s>
<s>
The	O
latter	O
is	O
normally	O
achieved	O
through	O
the	O
use	O
of	O
Signal	B-Application
transition	I-Application
graphs	I-Application
(	O
STGs	O
)	O
.	O
</s>
