<s>
BitFunnel	B-Algorithm
is	O
the	O
search	B-Application
engine	I-Application
indexing	I-Application
algorithm	O
and	O
a	O
set	O
of	O
components	O
used	O
in	O
the	O
Bing	B-Application
search	I-Application
engine	I-Application
,	O
which	O
were	O
made	O
open	O
source	O
in	O
2016	O
.	O
</s>
<s>
BitFunnel	B-Algorithm
uses	O
bit-sliced	O
signatures	O
instead	O
of	O
an	O
inverted	B-Algorithm
index	I-Algorithm
in	O
an	O
attempt	O
to	O
reduce	O
operations	O
cost	O
.	O
</s>
<s>
Progress	O
on	O
the	O
implementation	O
of	O
BitFunnel	B-Algorithm
was	O
made	O
public	O
in	O
early	O
2016	O
,	O
with	O
the	O
expectation	O
that	O
there	O
would	O
be	O
a	O
usable	O
implementation	O
later	O
that	O
year	O
.	O
</s>
<s>
In	O
September	O
2016	O
,	O
the	O
source	O
code	O
was	O
made	O
available	O
via	O
GitHub	B-Application
.	O
</s>
<s>
A	O
paper	O
discussing	O
the	O
BitFunnel	B-Algorithm
algorithm	O
and	O
implementation	O
was	O
released	O
as	O
through	O
the	O
Special	O
Interest	O
Group	O
on	O
Information	O
Retrieval	O
of	O
the	O
Association	O
for	O
Computing	O
Machinery	O
in	O
2017	O
and	O
won	O
the	O
Best	O
Paper	O
Award	O
.	O
</s>
<s>
BitFunnel	B-Algorithm
consists	O
of	O
three	O
major	O
components	O
:	O
</s>
<s>
The	O
BitFunnel	B-Algorithm
paper	O
describes	O
the	O
"	O
matching	O
problem	O
"	O
,	O
which	O
occurs	O
when	O
an	O
algorithm	O
must	O
identify	O
documents	O
through	O
the	O
usage	O
of	O
keywords	O
.	O
</s>
<s>
This	O
problem	O
is	O
commonly	O
solved	O
through	O
inverted	B-Algorithm
indexes	I-Algorithm
,	O
where	O
each	O
searchable	O
item	O
is	O
maintained	O
with	O
a	O
map	B-Application
of	O
keywords	O
.	O
</s>
<s>
In	O
contrast	O
,	O
BitFunnel	B-Algorithm
represents	O
each	O
searchable	O
item	O
through	O
a	O
signature	O
.	O
</s>
<s>
A	O
signature	O
is	O
a	O
sequence	O
of	O
bits	O
which	O
describe	O
a	O
Bloom	B-Algorithm
filter	I-Algorithm
of	O
the	O
searchable	O
terms	O
in	O
a	O
given	O
searchable	O
item	O
.	O
</s>
<s>
The	O
bloom	B-Algorithm
filter	I-Algorithm
is	O
constructed	O
through	O
hashing	O
through	O
several	O
bit	O
positions	O
.	O
</s>
