<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
compressed	B-Algorithm
pattern	I-Algorithm
matching	I-Algorithm
(	O
abbreviated	O
as	O
CPM	O
)	O
is	O
the	O
process	O
of	O
searching	O
for	O
patterns	O
in	O
compressed	B-General_Concept
data	I-General_Concept
with	O
little	O
or	O
no	O
decompression	O
.	O
</s>
<s>
Searching	O
in	O
a	O
compressed	B-General_Concept
string	O
is	O
faster	O
than	O
searching	O
an	O
uncompressed	B-General_Concept
string	O
and	O
requires	O
less	O
space	O
.	O
</s>
<s>
If	O
the	O
compressed	B-General_Concept
file	O
uses	O
a	O
variable	O
width	O
encoding	O
it	O
could	O
be	O
present	O
a	O
problem	O
:	O
for	O
example	O
,	O
let	O
“	O
100	O
”	O
be	O
the	O
codeword	O
for	O
a	O
and	O
let	O
“	O
110100	O
”	O
be	O
the	O
codeword	O
for	O
b	O
.	O
</s>
<s>
However	O
we	O
could	O
always	O
decode	O
the	O
entire	O
text	O
and	O
then	O
apply	O
a	O
classic	O
string	B-Algorithm
matching	I-Algorithm
algorithm	I-Algorithm
,	O
but	O
this	O
usually	O
requires	O
more	O
space	O
and	O
time	O
and	O
often	O
is	O
not	O
possible	O
,	O
for	O
example	O
if	O
the	O
compressed	B-General_Concept
file	O
is	O
hosted	O
online	O
.	O
</s>
<s>
This	O
problem	O
of	O
verifying	O
the	O
match	O
returned	O
by	O
the	O
compressed	B-Algorithm
pattern	I-Algorithm
matching	I-Algorithm
algorithm	O
is	O
a	O
true	O
or	O
a	O
false	O
match	O
together	O
with	O
the	O
impossibility	O
of	O
decoding	O
an	O
entire	O
text	O
is	O
called	O
the	O
compressed	B-General_Concept
matching	O
problem	O
.	O
</s>
