<s>
CiteSeerX	B-Application
(	O
formerly	O
called	O
CiteSeer	B-Application
)	O
is	O
a	O
public	O
search	B-Application
engine	I-Application
and	O
digital	O
library	O
for	O
scientific	O
and	O
academic	O
papers	O
,	O
primarily	O
in	O
the	O
fields	O
of	O
computer	B-General_Concept
and	O
information	O
science	O
.	O
</s>
<s>
CiteSeer	B-Application
's	O
goal	O
is	O
to	O
improve	O
the	O
dissemination	O
and	O
access	O
of	O
academic	O
and	O
scientific	O
literature	O
.	O
</s>
<s>
CiteSeer	B-Application
freely	O
provided	O
Open	O
Archives	O
Initiative	O
metadata	O
of	O
all	O
indexed	O
documents	O
and	O
links	O
indexed	O
documents	O
when	O
possible	O
to	O
other	O
sources	O
of	O
metadata	O
such	O
as	O
DBLP	O
and	O
the	O
ACM	B-Application
Portal	I-Application
.	O
</s>
<s>
To	O
promote	O
open	O
data	O
,	O
CiteSeerX	B-Application
shares	O
its	O
data	O
for	O
non-commercial	O
purposes	O
under	O
a	O
Creative	O
Commons	O
license	O
.	O
</s>
<s>
CiteSeer	B-Application
is	O
considered	O
as	O
a	O
predecessor	O
of	O
academic	O
search	O
tools	O
such	O
as	O
Google	B-Library
Scholar	I-Library
and	O
Microsoft	B-Application
Academic	I-Application
Search	I-Application
.	O
</s>
<s>
CiteSeer-like	O
engines	O
and	O
archives	O
usually	O
only	O
harvest	O
documents	O
from	O
publicly	O
available	O
websites	O
and	O
do	O
not	O
crawl	O
publisher	O
websites	O
.	O
</s>
<s>
CiteSeer	B-Application
changed	O
its	O
name	O
to	O
ResearchIndex	B-Application
at	O
one	O
point	O
and	O
then	O
changed	O
it	O
back	O
.	O
</s>
<s>
CiteSeer	B-Application
was	O
created	O
by	O
researchers	O
Lee	O
Giles	O
,	O
Kurt	O
Bollacker	O
and	O
Steve	O
Lawrence	O
in	O
1997	O
while	O
they	O
were	O
at	O
the	O
NEC	O
Research	O
Institute	O
(	O
now	O
NEC	O
Labs	O
)	O
,	O
Princeton	O
,	O
New	O
Jersey	O
,	O
US	O
.	O
</s>
<s>
CiteSeer	B-Application
's	O
goal	O
was	O
to	O
actively	O
crawl	O
and	O
harvest	O
academic	O
and	O
scientific	O
documents	O
on	O
the	O
web	O
and	O
use	O
autonomous	O
citation	O
indexing	O
to	O
permit	O
querying	O
by	O
citation	O
or	O
by	O
document	O
,	O
ranking	O
them	O
by	O
citation	O
impact	O
.	O
</s>
<s>
At	O
one	O
point	O
,	O
it	O
was	O
called	O
ResearchIndex	B-Application
.	O
</s>
<s>
CiteSeer	B-Application
became	O
public	O
in	O
1998	O
and	O
had	O
many	O
new	O
features	O
unavailable	O
in	O
academic	B-Library
search	I-Library
engines	I-Library
at	O
that	O
time	O
.	O
</s>
<s>
CiteSeer	B-Application
was	O
granted	O
a	O
United	O
States	O
patent	O
#6289342	O
,	O
titled	O
"	O
Autonomous	O
citation	O
indexing	O
and	O
literature	O
browsing	O
using	O
citation	O
context	O
"	O
,	O
on	O
September	O
11	O
,	O
2001	O
.	O
</s>
<s>
After	O
NEC	O
,	O
in	O
2004	O
it	O
was	O
hosted	O
as	O
CiteSeer.IST	B-Application
on	O
the	O
World	O
Wide	O
Web	O
at	O
the	O
College	O
of	O
Information	O
Sciences	O
and	O
Technology	O
,	O
The	O
Pennsylvania	O
State	O
University	O
,	O
and	O
had	O
over	O
700,000	O
documents	O
.	O
</s>
<s>
For	O
enhanced	O
access	O
,	O
performance	O
and	O
research	O
,	O
similar	O
versions	O
of	O
CiteSeer	B-Application
were	O
supported	O
at	O
universities	O
such	O
as	O
the	O
Massachusetts	O
Institute	O
of	O
Technology	O
,	O
University	O
of	O
Zürich	O
and	O
the	O
National	O
University	O
of	O
Singapore	O
.	O
</s>
<s>
However	O
,	O
these	O
versions	O
of	O
CiteSeer	B-Application
proved	O
difficult	O
to	O
maintain	O
and	O
are	O
no	O
longer	O
available	O
.	O
</s>
<s>
Because	O
CiteSeer	B-Application
only	O
indexes	O
freely	O
available	O
papers	O
on	O
the	O
web	O
and	O
does	O
not	O
have	O
access	O
to	O
publisher	O
metadata	O
,	O
it	O
returns	O
fewer	O
citation	O
counts	O
than	O
sites	O
,	O
such	O
as	O
Google	B-Library
Scholar	I-Library
,	O
that	O
have	O
publisher	O
metadata	O
.	O
</s>
<s>
CiteSeer	B-Application
had	O
not	O
been	O
comprehensively	O
updated	O
since	O
2005	O
due	O
to	O
limitations	O
in	O
its	O
architecture	O
design	O
.	O
</s>
<s>
It	O
had	O
a	O
representative	O
sampling	O
of	O
research	O
documents	O
in	O
computer	B-General_Concept
and	O
information	O
science	O
but	O
was	O
limited	O
in	O
coverage	O
because	O
it	O
was	O
limited	O
to	O
papers	O
that	O
are	O
publicly	O
available	O
,	O
usually	O
at	O
an	O
author	O
's	O
homepage	O
,	O
or	O
those	O
submitted	O
by	O
an	O
author	O
.	O
</s>
<s>
To	O
overcome	O
some	O
of	O
these	O
limitations	O
,	O
a	O
modular	O
and	O
open	B-Application
source	I-Application
architecture	O
for	O
CiteSeer	B-Application
was	O
designed	O
–	O
CiteSeerX	B-Application
.	O
</s>
<s>
CiteSeerX	B-Application
replaced	O
CiteSeer	B-Application
and	O
all	O
queries	O
to	O
CiteSeer	B-Application
were	O
redirected	O
.	O
</s>
<s>
CiteSeerX	B-Application
is	O
a	O
public	O
search	B-Application
engine	I-Application
and	O
digital	O
library	O
and	O
repository	O
for	O
scientific	O
and	O
academic	O
papers	O
primarily	O
with	O
a	O
focus	O
on	O
computer	B-General_Concept
and	O
information	O
science	O
.	O
</s>
<s>
However	O
,	O
recently	O
CiteSeerX	B-Application
has	O
been	O
expanding	O
into	O
other	O
scholarly	O
domains	O
such	O
as	O
economics	O
,	O
physics	O
and	O
others	O
.	O
</s>
<s>
Released	O
in	O
2008	O
,	O
it	O
was	O
loosely	O
based	O
on	O
the	O
previous	O
CiteSeer	B-Application
search	B-Application
engine	I-Application
and	O
digital	O
library	O
and	O
is	O
built	O
with	O
a	O
new	O
open	B-Application
source	I-Application
infrastructure	O
,	O
SeerSuite	O
,	O
and	O
new	O
algorithms	O
and	O
their	O
implementations	O
.	O
</s>
<s>
It	O
continues	O
to	O
support	O
the	O
goals	O
outlined	O
by	O
CiteSeer	B-Application
to	O
actively	O
crawl	O
and	O
harvest	O
academic	O
and	O
scientific	O
documents	O
on	O
the	O
public	O
web	O
and	O
to	O
use	O
a	O
citation	O
inquiry	O
by	O
citations	O
and	O
ranking	O
of	O
documents	O
by	O
the	O
impact	O
of	O
citations	O
.	O
</s>
<s>
Recently	O
,	O
a	O
table	O
search	B-Application
feature	I-Application
was	O
introduced	O
.	O
</s>
<s>
CiteSeerX	B-Application
continues	O
to	O
be	O
rated	O
as	O
one	O
of	O
the	O
world	O
's	O
top	O
repositories	O
and	O
was	O
rated	O
number	O
1	O
in	O
July	O
2010	O
.	O
</s>
<s>
CiteSeerX	B-Application
also	O
shares	O
its	O
software	O
,	O
data	O
,	O
databases	O
and	O
metadata	O
with	O
other	O
researchers	O
,	O
currently	O
by	O
Amazon	B-General_Concept
S3	I-General_Concept
and	O
by	O
rsync	B-Application
.	O
</s>
<s>
Its	O
new	O
modular	O
open	B-Application
source	I-Application
architecture	O
and	O
software	O
(	O
available	O
previously	O
on	O
SourceForge	B-Application
but	O
now	O
on	O
GitHub	B-Application
)	O
is	O
built	O
on	O
Apache	B-Language
Solr	I-Language
and	O
other	O
Apache	O
and	O
open	B-Application
source	I-Application
tools	O
which	O
allows	O
it	O
to	O
be	O
a	O
testbed	O
for	O
new	O
algorithms	O
in	O
document	O
harvesting	O
,	O
ranking	O
,	O
indexing	O
,	O
and	O
information	B-General_Concept
extraction	I-General_Concept
.	O
</s>
<s>
CiteSeerX	B-Application
caches	O
some	O
PDF	O
files	O
that	O
it	O
has	O
scanned	O
.	O
</s>
<s>
CiteSeerX	B-Application
uses	O
automated	O
information	B-General_Concept
extraction	I-General_Concept
tools	O
,	O
usually	O
built	O
on	O
machine	O
learning	O
methods	O
such	O
ParsCit	O
,	O
to	O
extract	O
scholarly	O
document	O
metadata	O
such	O
as	O
title	O
,	O
authors	O
,	O
abstract	O
,	O
citations	O
,	O
etc	O
.	O
</s>
<s>
Other	O
academic	B-Library
search	I-Library
engines	I-Library
have	O
similar	O
errors	O
.	O
</s>
<s>
CiteSeerX	B-Application
crawls	O
publicly	O
available	O
scholarly	O
documents	O
primarily	O
from	O
author	O
webpages	O
and	O
other	O
open	O
resources	O
,	O
and	O
does	O
not	O
have	O
access	O
to	O
publisher	O
metadata	O
.	O
</s>
<s>
As	O
such	O
citation	O
counts	O
in	O
CiteSeerX	B-Application
are	O
usually	O
less	O
than	O
those	O
in	O
Google	B-Library
Scholar	I-Library
and	O
Microsoft	B-Application
Academic	I-Application
Search	I-Application
who	O
have	O
access	O
to	O
publisher	O
metadata	O
.	O
</s>
<s>
CiteSeerX	B-Application
has	O
nearly	O
1	O
million	O
users	O
worldwide	O
based	O
on	O
unique	O
IP	O
addresses	O
and	O
has	O
millions	O
of	O
hits	O
daily	O
.	O
</s>
<s>
CiteSeerX	B-Application
data	O
is	O
regularly	O
shared	O
under	O
a	O
Creative	O
Commons	O
BY-NC-SA	O
license	O
with	O
researchers	O
worldwide	O
and	O
has	O
been	O
and	O
is	O
used	O
in	O
many	O
experiments	O
and	O
competitions	O
.	O
</s>
<s>
Thanks	O
to	O
its	O
OAI-PMH	O
endpoint	O
,	O
CiteSeerX	B-Application
is	O
an	O
open	O
archive	O
and	O
its	O
content	O
is	O
indexed	O
like	O
an	O
institutional	O
repository	O
in	O
academic	B-Library
search	I-Library
engines	I-Library
,	O
for	O
instance	O
BASE	B-Application
and	O
Unpaywall	O
consumers	O
.	O
</s>
<s>
The	O
CiteSeer	B-Application
model	O
had	O
been	O
extended	O
to	O
cover	O
academic	O
documents	O
in	O
business	O
with	O
SmealSearch	B-Application
and	O
in	O
e-business	O
with	O
eBizSearch	O
.	O
</s>
<s>
An	O
older	O
version	O
of	O
both	O
of	O
these	O
could	O
be	O
once	O
found	O
at	O
BizSeer.IST	O
but	O
is	O
no	O
longer	O
in	O
service	O
.	O
</s>
<s>
Other	O
Seer-like	O
search	O
and	O
repository	O
systems	O
have	O
been	O
built	O
for	O
chemistry	O
,	O
ChemXSeer	B-Library
and	O
for	O
archaeology	O
,	O
ArchSeer	O
.	O
</s>
<s>
All	O
of	O
these	O
are	O
built	O
on	O
the	O
open	B-Application
source	I-Application
tool	O
SeerSuite	O
,	O
which	O
uses	O
the	O
open	B-Application
source	I-Application
indexer	O
Lucene	B-Language
.	O
</s>
