<s>
SPIN	O
is	O
a	O
general	O
tool	O
for	O
verifying	O
the	O
correctness	O
of	O
concurrent	B-Operating_System
software	I-Operating_System
models	O
in	O
a	O
rigorous	O
and	O
mostly	O
automated	O
fashion	O
.	O
</s>
<s>
Systems	O
to	O
be	O
verified	O
are	O
described	O
in	O
Promela	B-Application
(	O
Process	O
Meta	O
Language	O
)	O
,	O
which	O
supports	O
modeling	O
of	O
asynchronous	O
distributed	B-Operating_System
algorithms	I-Operating_System
as	O
non-deterministic	O
automata	B-Application
(	O
SPIN	O
stands	O
for	O
"	O
Simple	O
Promela	B-Application
Interpreter	O
"	O
)	O
.	O
</s>
<s>
Properties	O
to	O
be	O
verified	O
are	O
expressed	O
as	O
Linear	O
Temporal	O
Logic	O
(	O
LTL	O
)	O
formulas	O
,	O
which	O
are	O
negated	O
and	O
then	O
converted	O
into	O
Büchi	B-General_Concept
automata	I-General_Concept
as	O
part	O
of	O
the	O
model-checking	B-Application
algorithm	O
.	O
</s>
<s>
In	O
addition	O
to	O
model-checking	B-Application
,	O
SPIN	O
can	O
also	O
operate	O
as	O
a	O
simulator	O
,	O
following	O
one	O
possible	O
execution	O
path	O
through	O
the	O
system	O
and	O
presenting	O
the	O
resulting	O
execution	O
trace	O
to	O
the	O
user	O
.	O
</s>
<s>
Unlike	O
many	O
model-checkers	B-Application
,	O
SPIN	O
does	O
not	O
actually	O
perform	O
model-checking	B-Application
itself	O
,	O
but	O
instead	O
generates	O
C	B-Language
sources	O
for	O
a	O
problem-specific	O
model	B-Application
checker	I-Application
.	O
</s>
<s>
This	O
technique	O
saves	O
memory	O
and	O
improves	O
performance	O
,	O
while	O
also	O
allowing	O
the	O
direct	O
insertion	O
of	O
chunks	O
of	O
C	B-Language
code	O
into	O
the	O
model	O
.	O
</s>
<s>
SPIN	O
also	O
offers	O
a	O
large	O
number	O
of	O
options	O
to	O
further	O
speed	O
up	O
the	O
model-checking	B-Application
process	O
and	O
save	O
memory	O
,	O
such	O
as	O
:	O
</s>
<s>
partial	B-Application
order	I-Application
reduction	I-Application
;	O
</s>
<s>
state	O
compression	B-General_Concept
;	O
</s>
<s>
bitstate	B-Error_Name
hashing	I-Error_Name
(	O
instead	O
of	O
storing	O
whole	O
states	O
,	O
only	O
their	O
hash	O
code	O
is	O
remembered	O
in	O
a	O
bitfield	O
;	O
this	O
saves	O
a	O
lot	O
of	O
memory	O
but	O
voids	O
completeness	O
)	O
;	O
</s>
<s>
Since	O
1995	O
,	O
(	O
approximately	O
)	O
annual	O
SPIN	O
workshops	O
have	O
been	O
held	O
for	O
SPIN	O
users	O
,	O
researchers	O
,	O
and	O
those	O
generally	O
interested	O
in	O
model	B-Application
checking	I-Application
.	O
</s>
