<s>
Information	B-Library
retrieval	I-Library
(	O
IR	O
)	O
in	O
computing	O
and	O
information	O
science	O
is	O
the	O
process	O
of	O
obtaining	O
information	O
system	O
resources	O
that	O
are	O
relevant	O
to	O
an	O
information	O
need	O
from	O
a	O
collection	O
of	O
those	O
resources	O
.	O
</s>
<s>
Searches	O
can	O
be	O
based	O
on	O
full-text	B-Application
or	O
other	O
content-based	O
indexing	O
.	O
</s>
<s>
Information	B-Library
retrieval	I-Library
is	O
the	O
science	O
of	O
searching	O
for	O
information	O
in	O
a	O
document	O
,	O
searching	O
for	O
documents	O
themselves	O
,	O
and	O
also	O
searching	O
for	O
the	O
metadata	O
that	O
describes	O
data	O
,	O
and	O
for	O
databases	O
of	O
texts	O
,	O
images	O
or	O
sounds	O
.	O
</s>
<s>
Automated	O
information	B-Library
retrieval	I-Library
systems	I-Library
are	O
used	O
to	O
reduce	O
what	O
has	O
been	O
called	O
information	O
overload	O
.	O
</s>
<s>
Web	B-Application
search	I-Application
engines	I-Application
are	O
the	O
most	O
visible	O
IR	O
applications	O
.	O
</s>
<s>
An	O
information	B-Library
retrieval	I-Library
process	O
begins	O
when	O
a	O
user	O
or	O
searcher	O
enters	O
a	O
query	B-Library
into	O
the	O
system	O
.	O
</s>
<s>
Queries	B-Library
are	O
formal	O
statements	O
of	O
information	O
needs	O
,	O
for	O
example	O
search	O
strings	O
in	O
web	B-Application
search	I-Application
engines	I-Application
.	O
</s>
<s>
In	O
information	B-Library
retrieval	I-Library
a	O
query	B-Library
does	O
not	O
uniquely	O
identify	O
a	O
single	O
object	O
in	O
the	O
collection	O
.	O
</s>
<s>
Instead	O
,	O
several	O
objects	O
may	O
match	O
the	O
query	B-Library
,	O
perhaps	O
with	O
different	O
degrees	O
of	O
relevance	O
.	O
</s>
<s>
User	O
queries	B-Library
are	O
matched	O
against	O
the	O
database	O
information	O
.	O
</s>
<s>
However	O
,	O
as	O
opposed	O
to	O
classical	O
SQL	O
queries	B-Library
of	O
a	O
database	O
,	O
in	O
information	B-Library
retrieval	I-Library
the	O
results	O
returned	O
may	O
or	O
may	O
not	O
match	O
the	O
query	B-Library
,	O
so	O
results	O
are	O
typically	O
ranked	O
.	O
</s>
<s>
This	O
ranking	O
of	O
results	O
is	O
a	O
key	O
difference	O
of	O
information	B-Library
retrieval	I-Library
searching	O
compared	O
to	O
database	O
searching	O
.	O
</s>
<s>
Most	O
IR	O
systems	O
compute	O
a	O
numeric	O
score	O
on	O
how	O
well	O
each	O
object	O
in	O
the	O
database	O
matches	O
the	O
query	B-Library
,	O
and	O
rank	O
the	O
objects	O
according	O
to	O
this	O
value	O
.	O
</s>
<s>
The	O
process	O
may	O
then	O
be	O
iterated	O
if	O
the	O
user	O
wishes	O
to	O
refine	O
the	O
query	B-Library
.	O
</s>
<s>
Automated	O
information	B-Library
retrieval	I-Library
systems	I-Library
were	O
introduced	O
in	O
the	O
1950s	O
:	O
one	O
even	O
featured	O
in	O
the	O
1957	O
romantic	O
comedy	O
,	O
Desk	O
Set	O
.	O
</s>
<s>
In	O
the	O
1960s	O
,	O
the	O
first	O
large	O
information	B-Library
retrieval	I-Library
research	O
group	O
was	O
formed	O
by	O
Gerard	O
Salton	O
at	O
Cornell	O
.	O
</s>
<s>
Large-scale	O
retrieval	O
systems	O
,	O
such	O
as	O
the	O
Lockheed	O
Dialog	O
system	O
,	O
came	O
into	O
use	O
early	O
in	O
the	O
1970s	O
.	O
</s>
<s>
In	O
1992	O
,	O
the	O
US	O
Department	O
of	O
Defense	O
along	O
with	O
the	O
National	O
Institute	O
of	O
Standards	O
and	O
Technology	O
(	O
NIST	O
)	O
,	O
cosponsored	O
the	O
Text	B-Language
Retrieval	I-Language
Conference	I-Language
(	O
TREC	B-Language
)	O
as	O
part	O
of	O
the	O
TIPSTER	O
text	O
program	O
.	O
</s>
<s>
The	O
aim	O
of	O
this	O
was	O
to	O
look	O
into	O
the	O
information	B-Library
retrieval	I-Library
community	O
by	O
supplying	O
the	O
infrastructure	O
that	O
was	O
needed	O
for	O
evaluation	O
of	O
text	O
retrieval	O
methodologies	O
on	O
a	O
very	O
large	O
text	O
collection	O
.	O
</s>
<s>
This	O
catalyzed	O
research	O
on	O
methods	O
that	O
scale	B-Architecture
to	O
huge	O
corpora	O
.	O
</s>
<s>
The	O
introduction	O
of	O
web	B-Application
search	I-Application
engines	I-Application
has	O
boosted	O
the	O
need	O
for	O
very	O
large	O
scale	B-Architecture
retrieval	O
systems	O
even	O
further	O
.	O
</s>
<s>
Areas	O
where	O
information	B-Library
retrieval	I-Library
techniques	O
are	O
employed	O
include	O
(	O
the	O
entries	O
are	O
in	O
alphabetical	O
order	O
within	O
each	O
category	O
)	O
:	O
</s>
<s>
Methods/Techniques	O
in	O
which	O
information	B-Library
retrieval	I-Library
techniques	O
are	O
employed	O
include	O
:	O
</s>
<s>
Algebraic	O
models	O
represent	O
documents	O
and	O
queries	B-Library
usually	O
as	O
vectors	O
,	O
matrices	O
,	O
or	O
tuples	O
.	O
</s>
<s>
The	O
similarity	O
of	O
the	O
query	B-Library
vector	O
and	O
document	O
vector	O
is	O
represented	O
as	O
a	O
scalar	O
value	O
.	O
</s>
<s>
Similarities	O
are	O
computed	O
as	O
probabilities	O
that	O
a	O
document	O
is	O
relevant	O
for	O
a	O
given	O
query	B-Library
.	O
</s>
<s>
Feature	O
functions	O
are	O
arbitrary	O
functions	O
of	O
document	O
and	O
query	B-Library
,	O
and	O
as	O
such	O
can	O
easily	O
incorporate	O
almost	O
any	O
other	O
retrieval	O
model	O
as	O
just	O
another	O
feature	O
.	O
</s>
<s>
This	O
fact	O
is	O
usually	O
represented	O
in	O
vector	O
space	O
models	O
by	O
the	O
orthogonality	B-Application
assumption	O
of	O
term	O
vectors	O
or	O
in	O
probabilistic	O
models	O
by	O
an	O
independency	O
assumption	O
for	O
term	O
variables	O
.	O
</s>
<s>
by	O
dimensional	B-Algorithm
reduction	I-Algorithm
)	O
from	O
the	O
co-occurrence	O
of	O
those	O
terms	O
in	O
the	O
whole	O
set	O
of	O
documents	O
.	O
</s>
<s>
The	O
evaluation	O
of	O
an	O
information	B-Library
retrieval	I-Library
system	I-Library
 '	O
is	O
the	O
process	O
of	O
assessing	O
how	O
well	O
a	O
system	O
meets	O
the	O
information	O
needs	O
of	O
its	O
users	O
.	O
</s>
<s>
In	O
general	O
,	O
measurement	O
considers	O
a	O
collection	O
of	O
documents	O
to	O
be	O
searched	O
and	O
a	O
search	O
query	B-Library
.	O
</s>
<s>
All	O
measures	O
assume	O
a	O
ground	B-General_Concept
truth	I-General_Concept
notion	O
of	O
relevance	O
:	O
every	O
document	O
is	O
known	O
to	O
be	O
either	O
relevant	O
or	O
non-relevant	O
to	O
a	O
particular	O
query	B-Library
.	O
</s>
<s>
In	O
practice	O
,	O
queries	B-Library
may	O
be	O
ill-posed	B-Algorithm
and	O
there	O
may	O
be	O
different	O
shades	O
of	O
relevance	O
.	O
</s>
<s>
1801	O
:	O
Joseph	O
Marie	O
Jacquard	O
invents	O
the	O
Jacquard	O
loom	O
,	O
the	O
first	O
machine	O
to	O
use	O
punched	B-Architecture
cards	I-Architecture
to	O
control	O
a	O
sequence	O
of	O
operations	O
.	O
</s>
<s>
1880s	O
:	O
Herman	O
Hollerith	O
invents	O
an	O
electro-mechanical	O
data	O
tabulator	O
using	O
punch	B-Architecture
cards	I-Architecture
as	O
a	O
machine	O
readable	O
medium	O
.	O
</s>
<s>
1890	O
Hollerith	B-Architecture
cards	I-Architecture
,	O
keypunches	B-Device
and	O
tabulators	O
used	O
to	O
process	O
the	O
1890	O
US	O
Census	O
data	O
.	O
</s>
<s>
Emanuel	O
Goldberg	O
submits	O
patents	O
for	O
his	O
"	O
Statistical	O
Machine	O
”	O
a	O
document	O
search	B-Application
engine	I-Application
that	O
used	O
photoelectric	O
cells	O
and	O
pattern	O
recognition	O
to	O
search	O
the	O
metadata	O
on	O
rolls	O
of	O
microfilmed	O
documents	O
.	O
</s>
<s>
1950	O
:	O
The	O
term	O
"	O
information	B-Library
retrieval	I-Library
"	O
was	O
coined	O
by	O
Calvin	O
Mooers	O
.	O
</s>
<s>
1960	O
:	O
Melvin	O
Earl	O
Maron	O
and	O
John	O
Lary	O
Kuhns	O
published	O
"	O
On	O
relevance	O
,	O
probabilistic	O
indexing	O
,	O
and	O
information	B-Library
retrieval	I-Library
"	O
in	O
the	O
Journal	O
of	O
the	O
ACM	O
7(3 )	O
:216	O
–	O
244	O
,	O
July	O
1960	O
.	O
</s>
<s>
Joseph	O
Becker	O
and	O
Robert	O
M	O
.	O
Hayes	O
published	O
text	O
on	O
information	B-Library
retrieval	I-Library
.	O
</s>
<s>
Several	O
highly	O
significant	O
papers	O
,	O
including	O
G	O
.	O
Salton	O
's	O
first	O
published	O
reference	O
(	O
we	O
believe	O
)	O
to	O
the	O
SMART	B-Application
system	O
.	O
</s>
<s>
late	O
1960s	O
:	O
F	O
.	O
Wilfrid	O
Lancaster	O
completed	O
evaluation	O
studies	O
of	O
the	O
MEDLARS	O
system	O
and	O
published	O
the	O
first	O
edition	O
of	O
his	O
text	O
on	O
information	B-Library
retrieval	I-Library
.	O
</s>
<s>
1971	O
:	O
Nicholas	O
Jardine	O
and	O
Cornelis	O
J	O
.	O
van	O
Rijsbergen	O
published	O
"	O
The	O
use	O
of	O
hierarchic	O
clustering	O
in	O
information	B-Library
retrieval	I-Library
"	O
,	O
which	O
articulated	O
the	O
"	O
cluster	O
hypothesis.	O
"	O
</s>
<s>
1979	O
:	O
C	O
.	O
J	O
.	O
van	O
Rijsbergen	O
published	O
Information	B-Library
Retrieval	I-Library
(	O
Butterworths	O
)	O
.	O
</s>
<s>
1979	O
:	O
Tamas	O
Doszkocs	O
implemented	O
the	O
CITE	O
natural	B-General_Concept
language	I-General_Concept
user	I-General_Concept
interface	I-General_Concept
for	O
MEDLINE	O
at	O
the	O
National	O
Library	O
of	O
Medicine	O
.	O
</s>
<s>
The	O
CITE	O
system	O
supported	O
free	O
form	O
query	B-Library
input	O
,	O
ranked	O
output	O
and	O
relevance	O
feedback	O
.	O
</s>
<s>
1982	O
:	O
Nicholas	O
J	O
.	O
Belkin	O
,	O
Robert	O
N	O
.	O
Oddy	O
,	O
and	O
Helen	O
M	O
.	O
Brooks	O
proposed	O
the	O
ASK	O
(	O
Anomalous	O
State	O
of	O
Knowledge	O
)	O
viewpoint	O
for	O
information	B-Library
retrieval	I-Library
.	O
</s>
<s>
1983	O
:	O
Salton	O
(	O
and	O
Michael	O
J	O
.	O
McGill	O
)	O
published	O
Introduction	O
to	O
Modern	O
Information	B-Library
Retrieval	I-Library
(	O
McGraw-Hill	O
)	O
,	O
with	O
heavy	O
emphasis	O
on	O
vector	O
models	O
.	O
</s>
<s>
1992	O
:	O
First	O
TREC	B-Language
conference	O
.	O
</s>
<s>
1999	O
:	O
Publication	O
of	O
Ricardo	O
Baeza-Yates	O
and	O
Berthier	O
Ribeiro-Neto	O
'	O
s	O
Modern	O
Information	B-Library
Retrieval	I-Library
by	O
Addison	O
Wesley	O
,	O
the	O
first	O
book	O
that	O
attempts	O
to	O
cover	O
all	O
IR	O
.	O
</s>
<s>
late	O
1990s	O
:	O
Web	B-Application
search	I-Application
engines	I-Application
implementation	O
of	O
many	O
features	O
formerly	O
found	O
only	O
in	O
experimental	O
IR	O
systems	O
.	O
</s>
<s>
Search	B-Application
engines	I-Application
become	O
the	O
most	O
common	O
and	O
maybe	O
best	O
instantiation	O
of	O
IR	O
models	O
.	O
</s>
