<s>
Trigrams	B-General_Concept
are	O
a	O
special	O
case	O
of	O
the	O
n-gram	B-Language
,	O
where	O
n	O
is	O
3	O
.	O
</s>
<s>
They	O
are	O
often	O
used	O
in	O
natural	B-Language
language	I-Language
processing	I-Language
for	O
performing	O
statistical	O
analysis	O
of	O
texts	O
and	O
in	O
cryptography	O
for	O
control	O
and	O
use	O
of	O
ciphers	B-Application
and	O
codes	O
.	O
</s>
<s>
Typical	O
cryptanalytic	O
frequency	O
analysis	O
finds	O
that	O
the	O
16	O
most	O
common	O
character-level	O
trigrams	B-General_Concept
in	O
English	O
are	O
:	O
</s>
<s>
Because	O
encrypted	O
messages	O
sent	O
by	O
telegraph	O
often	O
omit	O
punctuation	O
and	O
spaces	O
,	O
cryptographic	O
frequency	O
analysis	O
of	O
such	O
messages	O
includes	O
trigrams	B-General_Concept
that	O
straddle	O
word	O
boundaries	O
.	O
</s>
<s>
This	O
causes	O
trigrams	B-General_Concept
such	O
as	O
"	O
edt	O
"	O
to	O
occur	O
frequently	O
,	O
even	O
though	O
it	O
may	O
never	O
occur	O
in	O
any	O
one	O
word	O
of	O
those	O
messages	O
.	O
</s>
<s>
The	O
sentence	O
"	O
the	O
quick	O
red	O
fox	O
jumps	O
over	O
the	O
lazy	O
brown	O
dog	O
"	O
has	O
the	O
following	O
word-level	O
trigrams	B-General_Concept
:	O
</s>
<s>
And	O
the	O
word-level	O
trigram	B-General_Concept
"	O
the	O
quick	O
red	O
"	O
has	O
the	O
following	O
character-level	O
trigrams	B-General_Concept
(	O
where	O
an	O
underscore	O
"	O
_	O
"	O
marks	O
a	O
space	O
)	O
:	O
</s>
