<s>
Native-language	B-General_Concept
identification	I-General_Concept
(	O
NLI	O
)	O
is	O
the	O
task	O
of	O
determining	O
an	O
author	O
's	O
native	O
language	O
(	O
L1	O
)	O
based	O
only	O
on	O
their	O
writings	O
in	O
a	O
second	O
language	O
(	O
L2	O
)	O
.	O
</s>
<s>
Natural	B-Language
language	I-Language
processing	I-Language
methods	O
are	O
used	O
to	O
extract	O
and	O
identify	O
language	O
usage	O
patterns	O
common	O
to	O
speakers	O
of	O
an	O
L1-group	O
.	O
</s>
<s>
Next	O
,	O
machine	O
learning	O
is	O
applied	O
to	O
train	O
classifiers	O
,	O
like	O
support	B-Algorithm
vector	I-Algorithm
machines	I-Algorithm
,	O
for	O
predicting	O
the	O
L1	O
of	O
unseen	O
texts	O
.	O
</s>
<s>
Surface	O
level	O
lexical	O
features	O
such	O
as	O
character	O
,	O
word	O
and	O
lemma	O
n-grams	B-Language
have	O
also	O
been	O
found	O
to	O
be	O
quite	O
useful	O
for	O
this	O
task	O
.	O
</s>
<s>
However	O
,	O
it	O
seems	O
that	O
character	O
n-grams	B-Language
are	O
the	O
single	O
best	O
feature	O
for	O
the	O
task	O
.	O
</s>
