<s>
Instance	B-Algorithm
selection	I-Algorithm
(	O
or	O
dataset	O
reduction	O
,	O
or	O
dataset	O
condensation	O
)	O
is	O
an	O
important	O
data	B-General_Concept
pre-processing	I-General_Concept
step	O
that	O
can	O
be	O
applied	O
in	O
many	O
machine	O
learning	O
(	O
or	O
data	B-Application
mining	I-Application
)	O
tasks	O
.	O
</s>
<s>
Approaches	O
for	O
instance	B-Algorithm
selection	I-Algorithm
can	O
be	O
applied	O
for	O
reducing	O
the	O
original	O
dataset	O
to	O
a	O
manageable	O
volume	O
,	O
leading	O
to	O
a	O
reduction	O
of	O
the	O
computational	O
resources	O
that	O
are	O
necessary	O
for	O
performing	O
the	O
learning	O
process	O
.	O
</s>
<s>
Algorithms	O
of	O
instance	B-Algorithm
selection	I-Algorithm
can	O
also	O
be	O
applied	O
for	O
removing	O
noisy	O
instances	O
,	O
before	O
applying	O
learning	O
algorithms	O
.	O
</s>
<s>
Algorithm	O
for	O
instance	B-Algorithm
selection	I-Algorithm
should	O
identify	O
a	O
subset	O
of	O
the	O
total	O
available	O
data	O
to	O
achieve	O
the	O
original	O
purpose	O
of	O
the	O
data	B-Application
mining	I-Application
(	O
or	O
machine	O
learning	O
)	O
application	O
as	O
if	O
the	O
whole	O
data	O
had	O
been	O
used	O
.	O
</s>
<s>
Therefore	O
,	O
every	O
instance	B-Algorithm
selection	I-Algorithm
strategy	O
should	O
deal	O
with	O
a	O
trade-off	O
between	O
the	O
reduction	O
rate	O
of	O
the	O
dataset	O
and	O
the	O
classification	O
quality	O
.	O
</s>
<s>
The	O
literature	O
provides	O
several	O
different	O
algorithms	O
for	O
instance	B-Algorithm
selection	I-Algorithm
.	O
</s>
<s>
Considering	O
this	O
,	O
instance	B-Algorithm
selection	I-Algorithm
algorithms	O
can	O
be	O
grouped	O
in	O
two	O
main	O
classes	O
,	O
according	O
to	O
what	O
instances	O
they	O
select	O
:	O
algorithms	O
that	O
preserve	O
the	O
instances	O
at	O
the	O
boundaries	O
of	O
classes	O
and	O
algorithms	O
that	O
preserve	O
the	O
internal	O
instances	O
of	O
the	O
classes	O
.	O
</s>
<s>
They	O
do	O
not	O
reduce	O
the	O
data	O
as	O
the	O
algorithms	O
that	O
select	O
border	O
instances	O
,	O
but	O
they	O
remove	O
instances	O
at	O
the	O
boundaries	O
that	O
have	O
a	O
negative	O
impact	O
on	O
the	O
data	B-Application
mining	I-Application
task	O
.	O
</s>
<s>
They	O
can	O
be	O
used	O
by	O
other	O
instance	B-Algorithm
selection	I-Algorithm
algorithms	O
,	O
as	O
a	O
filtering	O
step	O
.	O
</s>
