<s>
Incremental	B-Data_Structure
encoding	I-Data_Structure
,	O
also	O
known	O
as	O
front	B-Data_Structure
compression	I-Data_Structure
,	O
back	B-Data_Structure
compression	I-Data_Structure
,	O
or	O
front	O
coding	O
,	O
is	O
a	O
type	O
of	O
delta	B-Algorithm
encoding	I-Algorithm
compression	B-General_Concept
algorithm	I-General_Concept
whereby	O
common	O
prefixes	O
or	O
suffixes	O
and	O
their	O
lengths	O
are	O
recorded	O
so	O
that	O
they	O
need	O
not	O
be	O
duplicated	O
.	O
</s>
<s>
This	O
algorithm	O
is	O
particularly	O
well-suited	O
for	O
compressing	O
sorted	B-Algorithm
data	O
,	O
e.g.	O
,	O
a	O
list	O
of	O
words	O
from	O
a	O
dictionary	B-Operating_System
.	O
</s>
<s>
Typical	O
techniques	O
are	O
storing	O
the	O
value	O
as	O
a	O
single	O
byte	O
;	O
delta	B-Algorithm
encoding	I-Algorithm
,	O
which	O
stores	O
only	O
the	O
change	O
in	O
the	O
common	O
prefix	O
length	O
;	O
and	O
various	O
universal	B-Algorithm
codes	I-Algorithm
.	O
</s>
<s>
It	O
may	O
be	O
combined	O
with	O
other	O
general	O
lossless	B-Algorithm
data	I-Algorithm
compression	I-Algorithm
techniques	O
such	O
as	O
entropy	B-Algorithm
encoding	I-Algorithm
and	O
dictionary	B-Algorithm
coders	I-Algorithm
to	O
compress	O
the	O
remaining	O
suffixes	O
.	O
</s>
<s>
Incremental	B-Data_Structure
encoding	I-Data_Structure
is	O
widely	O
used	O
in	O
information	O
retrieval	O
to	O
compress	O
the	O
lexicons	O
used	O
in	O
search	B-Application
indexes	I-Application
;	O
these	O
list	O
all	O
the	O
words	O
found	O
in	O
all	O
the	O
documents	O
and	O
a	O
pointer	O
for	O
each	O
one	O
to	O
a	O
list	O
of	O
locations	O
.	O
</s>
<s>
As	O
one	O
example	O
,	O
incremental	B-Data_Structure
encoding	I-Data_Structure
is	O
used	O
as	O
a	O
starting	O
point	O
by	O
the	O
GNU	B-Application
locate	I-Application
utility	O
,	O
in	O
an	O
index	O
of	O
filenames	O
and	O
directories	O
.	O
</s>
<s>
The	O
GNU	B-Application
locate	I-Application
utility	O
further	O
uses	O
bigram	O
encoding	O
to	O
further	O
shorten	O
popular	O
filepath	O
prefixes	O
.	O
</s>
