<s>
Bitstate	B-Error_Name
hashing	I-Error_Name
is	O
a	O
hashing	B-Error_Name
method	O
invented	O
in	O
1968	O
by	O
Morris	O
.	O
</s>
<s>
It	O
is	O
used	O
for	O
state	O
hashing	B-Error_Name
,	O
where	O
each	O
state	O
(	O
e.g.	O
</s>
<s>
of	O
an	O
automaton	O
)	O
is	O
represented	O
by	O
a	O
number	O
and	O
it	O
is	O
passed	O
to	O
some	O
hash	B-Error_Name
function	I-Error_Name
.	O
</s>
<s>
A	O
shortcoming	O
of	O
this	O
framework	O
is	O
losing	O
precision	O
like	O
in	O
other	O
hashing	B-Error_Name
techniques	O
.	O
</s>
<s>
Hence	O
some	O
tools	O
use	O
this	O
technique	O
with	O
more	O
than	O
one	O
hash	B-Error_Name
function	I-Error_Name
so	O
that	O
the	O
bit-field	O
gets	O
widened	O
by	O
the	O
number	O
of	O
used	O
functions	O
,	O
each	O
having	O
its	O
own	O
row	O
.	O
</s>
<s>
Bitstate	B-Error_Name
hashing	I-Error_Name
is	O
utilized	O
in	O
the	O
SPIN	O
model	O
checker	O
for	O
deciding	O
whether	O
a	O
state	O
was	O
already	O
visited	O
by	O
a	O
nested-depth-first	O
search	O
algorithm	O
or	O
not	O
.	O
</s>
<s>
This	O
purportedly	O
led	O
to	O
memory	O
savings	O
of	O
98%	O
in	O
the	O
case	O
of	O
using	O
one	O
hash	B-Error_Name
function	I-Error_Name
(	O
175	O
MB	O
to	O
3	O
MB	O
)	O
and	O
92%	O
when	O
two	O
hash	B-Error_Name
functions	I-Error_Name
are	O
used	O
(	O
13	O
MB	O
)	O
.	O
</s>
