<s>
An	O
information	B-Application
filtering	I-Application
system	I-Application
is	O
a	O
system	O
that	O
removes	O
redundant	B-General_Concept
or	O
unwanted	O
information	B-General_Concept
from	O
an	O
information	B-General_Concept
stream	O
using	O
(	O
semi	O
)	O
automated	O
or	O
computerized	O
methods	O
prior	O
to	O
presentation	O
to	O
a	O
human	O
user	O
.	O
</s>
<s>
Its	O
main	O
goal	O
is	O
the	O
management	O
of	O
the	O
information	B-General_Concept
overload	O
and	O
increment	O
of	O
the	O
semantic	O
signal-to-noise	O
ratio	O
.	O
</s>
<s>
These	O
characteristics	O
may	O
originate	O
from	O
the	O
information	B-General_Concept
item	O
(	O
the	O
content-based	O
approach	O
)	O
or	O
the	O
user	O
's	O
social	O
environment	O
(	O
the	O
collaborative	B-Algorithm
filtering	I-Algorithm
approach	O
)	O
.	O
</s>
<s>
Whereas	O
in	O
information	B-General_Concept
transmission	O
signal	O
processing	O
filters	O
are	O
used	O
against	O
syntax-disrupting	O
noise	O
on	O
the	O
bit-level	O
,	O
the	O
methods	O
employed	O
in	O
information	B-Application
filtering	I-Application
act	O
on	O
the	O
semantic	O
level	O
.	O
</s>
<s>
The	O
range	O
of	O
machine	O
methods	O
employed	O
builds	O
on	O
the	O
same	O
principles	O
as	O
those	O
for	O
information	B-General_Concept
extraction	I-General_Concept
.	O
</s>
<s>
Thus	O
,	O
it	O
is	O
not	O
only	O
the	O
information	B-General_Concept
explosion	O
that	O
necessitates	O
some	O
form	O
of	O
filters	O
,	O
but	O
also	O
inadvertently	O
or	O
maliciously	O
introduced	O
pseudo-information	O
.	O
</s>
<s>
On	O
the	O
presentation	O
level	O
,	O
information	B-Application
filtering	I-Application
takes	O
the	O
form	O
of	O
user-preferences-based	O
newsfeeds	B-Application
,	O
etc	O
.	O
</s>
<s>
Recommender	B-Application
systems	I-Application
and	O
content	B-Application
discovery	I-Application
platforms	I-Application
are	O
active	O
information	B-Application
filtering	I-Application
systems	I-Application
that	O
attempt	O
to	O
present	O
to	O
the	O
user	O
information	B-General_Concept
items	O
(	O
film	O
,	O
television	O
,	O
music	O
,	O
books	O
,	O
news	O
,	O
web	O
pages	O
)	O
the	O
user	O
is	O
interested	O
in	O
.	O
</s>
<s>
These	O
systems	O
add	O
information	B-General_Concept
items	O
to	O
the	O
information	B-General_Concept
flowing	O
towards	O
the	O
user	O
,	O
as	O
opposed	O
to	O
removing	O
information	B-General_Concept
items	O
from	O
the	O
information	B-General_Concept
flow	O
towards	O
the	O
user	O
.	O
</s>
<s>
Recommender	B-Application
systems	I-Application
typically	O
use	O
collaborative	B-Algorithm
filtering	I-Algorithm
approaches	O
or	O
a	O
combination	O
of	O
the	O
collaborative	B-Algorithm
filtering	I-Algorithm
and	O
content-based	O
filtering	O
approaches	O
,	O
although	O
content-based	O
recommender	B-Application
systems	I-Application
do	O
exist	O
.	O
</s>
<s>
Before	O
the	O
advent	O
of	O
the	O
Internet	O
,	O
there	O
are	O
already	O
several	O
methods	O
of	O
filtering	O
information	B-General_Concept
;	O
for	O
instance	O
,	O
governments	O
may	O
control	O
and	O
restrict	O
the	O
flow	O
of	O
information	B-General_Concept
in	O
a	O
given	O
country	O
by	O
means	O
of	O
formal	O
or	O
informal	O
censorship	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
we	O
are	O
going	O
to	O
talk	O
about	O
information	B-General_Concept
filters	O
if	O
we	O
refer	O
to	O
newspaper	O
editors	O
and	O
journalists	O
when	O
they	O
provide	O
a	O
service	O
that	O
selects	O
the	O
most	O
valuable	O
information	B-General_Concept
for	O
their	O
clients	O
,	O
readers	O
of	O
books	O
,	O
magazines	O
,	O
newspapers	O
,	O
radio	O
listeners	O
and	O
TV	B-Operating_System
viewers	O
.	O
</s>
<s>
This	O
filtering	O
operation	O
is	O
also	O
present	O
in	O
schools	O
and	O
universities	O
where	O
there	O
is	O
a	O
selection	O
of	O
information	B-General_Concept
to	O
provide	O
assistance	O
based	O
on	O
academic	O
criteria	O
to	O
customers	O
of	O
this	O
service	O
,	O
the	O
students	O
.	O
</s>
<s>
In	O
this	O
way	O
,	O
it	O
increases	O
considerably	O
the	O
less	O
useful	O
information	B-General_Concept
and	O
consequently	O
the	O
quality	O
information	B-General_Concept
is	O
disseminated	O
.	O
</s>
<s>
With	O
this	O
problem	O
,	O
it	O
began	O
to	O
devise	O
new	O
filtering	O
with	O
which	O
we	O
can	O
get	O
the	O
information	B-General_Concept
required	O
for	O
each	O
specific	O
topic	O
to	O
easily	O
and	O
efficiently	O
.	O
</s>
<s>
A	O
filtering	O
system	O
of	O
this	O
style	O
consists	O
of	O
several	O
tools	O
that	O
help	O
people	O
find	O
the	O
most	O
valuable	O
information	B-General_Concept
,	O
so	O
the	O
limited	O
time	O
you	O
can	O
dedicate	O
to	O
read	O
/	O
listen	O
/	O
view	O
,	O
is	O
correctly	O
directed	O
to	O
the	O
most	O
interesting	O
and	O
valuable	O
documents	O
.	O
</s>
<s>
These	O
filters	O
are	O
also	O
used	O
to	O
organize	O
and	O
structure	O
information	B-General_Concept
in	O
a	O
correct	O
and	O
understandable	O
way	O
,	O
in	O
addition	O
to	O
group	O
messages	O
on	O
the	O
mail	O
addressed	O
.	O
</s>
<s>
These	O
filters	O
are	O
essential	O
in	O
the	O
results	O
obtained	O
of	O
the	O
search	B-Application
engines	I-Application
on	O
the	O
Internet	O
.	O
</s>
<s>
In	O
this	O
case	O
the	O
task	O
of	O
information	B-Application
filtering	I-Application
to	O
reduce	O
or	O
eliminate	O
the	O
harmful	O
information	B-General_Concept
with	O
knowledge	O
.	O
</s>
<s>
Currently	O
the	O
problem	O
is	O
not	O
finding	O
the	O
best	O
way	O
to	O
filter	O
information	B-General_Concept
,	O
but	O
the	O
way	O
that	O
these	O
systems	O
require	O
to	O
learn	O
independently	O
the	O
information	B-General_Concept
needs	O
of	O
users	O
.	O
</s>
<s>
Some	O
branches	O
based	O
on	O
it	O
,	O
such	O
as	O
statistics	O
,	O
machine	O
learning	O
,	O
pattern	O
recognition	O
and	O
data	O
mining	O
,	O
are	O
the	O
base	O
for	O
developing	O
information	B-General_Concept
filters	O
that	O
appear	O
and	O
adapt	O
in	O
base	O
to	O
experience	O
.	O
</s>
<s>
To	O
carry	O
out	O
the	O
learning	O
process	O
,	O
part	O
of	O
the	O
information	B-General_Concept
has	O
to	O
be	O
pre-filtered	O
,	O
which	O
means	O
there	O
are	O
positive	O
and	O
negative	O
examples	O
which	O
we	O
named	O
training	O
data	O
,	O
which	O
can	O
be	O
generated	O
by	O
experts	O
,	O
or	O
via	O
feedback	O
from	O
ordinary	O
users	O
.	O
</s>
<s>
As	O
data	O
is	O
entered	O
,	O
the	O
system	O
includes	O
new	O
rules	O
;	O
if	O
we	O
consider	O
that	O
this	O
data	O
can	O
generalize	O
the	O
training	O
data	O
information	B-General_Concept
,	O
then	O
we	O
have	O
to	O
evaluate	O
the	O
system	O
development	O
and	O
measure	O
the	O
system	O
's	O
ability	O
to	O
correctly	O
predict	O
the	O
categories	O
of	O
new	O
information	B-General_Concept
.	O
</s>
<s>
For	O
example	O
,	O
in	O
the	O
case	O
on	O
an	O
aggregator	O
of	O
content	O
for	O
children	O
,	O
it	O
does	O
n't	O
have	O
the	O
same	O
gravity	O
to	O
allow	O
the	O
passage	O
of	O
information	B-General_Concept
not	O
suitable	O
for	O
them	O
,	O
that	O
shows	O
violence	O
or	O
pornography	O
,	O
than	O
the	O
mistake	O
to	O
discard	O
some	O
appropriated	O
information	B-General_Concept
.	O
</s>
<s>
To	O
improve	O
the	O
system	O
to	O
lower	O
error	O
rates	O
and	O
have	O
these	O
systems	O
with	O
learning	O
capabilities	O
similar	O
to	O
humans	O
we	O
require	O
development	O
of	O
systems	O
that	O
simulate	O
human	O
cognitive	O
abilities	O
,	O
such	O
as	O
natural-language	B-General_Concept
understanding	I-General_Concept
,	O
capturing	O
meaning	O
Common	O
and	O
other	O
forms	O
of	O
advanced	O
processing	O
to	O
achieve	O
the	O
semantics	O
of	O
information	B-General_Concept
.	O
</s>
<s>
Nowadays	O
,	O
there	O
are	O
numerous	O
techniques	O
to	O
develop	O
information	B-General_Concept
filters	O
,	O
some	O
of	O
these	O
reach	O
error	O
rates	O
lower	O
than	O
10%	O
in	O
various	O
experiments	O
.	O
</s>
