<s>
The	O
Calgary	B-General_Concept
corpus	I-General_Concept
is	O
a	O
collection	O
of	O
text	B-General_Concept
and	O
binary	O
data	O
files	O
,	O
commonly	O
used	O
for	O
comparing	O
data	B-General_Concept
compression	I-General_Concept
algorithms	I-General_Concept
.	O
</s>
<s>
In	O
1997	O
it	O
was	O
replaced	O
by	O
the	O
Canterbury	B-General_Concept
corpus	I-General_Concept
,	O
based	O
on	O
concerns	O
about	O
how	O
representative	O
the	O
Calgary	B-General_Concept
corpus	I-General_Concept
was	O
,	O
but	O
the	O
Calgary	B-General_Concept
corpus	I-General_Concept
still	O
exists	O
for	O
comparison	O
and	O
is	O
still	O
useful	O
for	O
its	O
originally	O
intended	O
purpose	O
.	O
</s>
<s>
Size	O
(	O
bytes	O
)	O
File	O
name	O
Description	O
111,261	O
BIB	O
ASCII	O
text	B-General_Concept
in	O
UNIX	O
"	O
refer	B-Application
"	O
format	O
–	O
725	O
bibliographic	O
references	O
.	O
</s>
<s>
768,771	O
BOOK1	O
unformatted	O
ASCII	O
text	B-General_Concept
–	O
Thomas	O
Hardy	O
:	O
Far	O
from	O
the	O
Madding	O
Crowd	O
.	O
</s>
<s>
610,856	O
BOOK2	O
ASCII	O
text	B-General_Concept
in	O
UNIX	O
"	O
troff	B-Language
"	O
format	O
–	O
Witten	O
:	O
Principles	O
of	O
Computer	O
Speech	O
.	O
</s>
<s>
377,109	O
NEWS	O
ASCII	O
text	B-General_Concept
–	O
USENET	B-Application
batch	O
file	O
on	O
a	O
variety	O
of	O
topics	O
.	O
</s>
<s>
21,504	O
OBJ1	O
VAX	B-Device
executable	O
program	O
–	O
compilation	O
of	O
PROGP	O
.	O
</s>
<s>
53,161	O
PAPER1	O
UNIX	O
"	O
troff	B-Language
"	O
format	O
–	O
Witten	O
,	O
Neal	O
,	O
Cleary	O
:	O
Arithmetic	O
Coding	O
for	O
Data	B-General_Concept
Compression	I-General_Concept
.	O
</s>
<s>
82,199	O
PAPER2	O
UNIX	O
"	O
troff	B-Language
"	O
format	O
–	O
Witten	O
:	O
Computer	O
(	O
in	O
)	O
security	O
.	O
</s>
<s>
513,216	O
PIC	O
1728	O
x	O
2376	O
bitmap	O
image	O
(	O
MSB	O
first	O
)	O
:	O
text	B-General_Concept
in	O
French	O
and	O
line	O
diagrams	O
.	O
</s>
<s>
39,611	O
PROGC	O
Source	O
code	O
in	O
C	O
–	O
UNIX	O
compress	B-Device
v4.0	O
.	O
</s>
<s>
There	O
is	O
also	O
a	O
less	O
commonly	O
used	O
18	O
file	O
version	O
which	O
include	O
4	O
additional	O
text	B-General_Concept
files	I-General_Concept
in	O
UNIX	O
"	O
troff	B-Language
"	O
format	O
,	O
PAPER3	O
through	O
PAPER6	O
.	O
</s>
<s>
The	O
maintainers	O
of	O
the	O
Canterbury	B-General_Concept
corpus	I-General_Concept
website	O
notes	O
that	O
"	O
they	O
do	O
n't	O
add	O
to	O
the	O
evaluation	O
"	O
.	O
</s>
<s>
The	O
Calgary	B-General_Concept
corpus	I-General_Concept
was	O
a	O
commonly	O
used	O
benchmark	O
for	O
data	B-General_Concept
compression	I-General_Concept
in	O
the	O
1990s	O
.	O
</s>
<s>
For	O
some	O
data	O
compressors	O
it	O
is	O
possible	O
to	O
compress	B-Device
the	O
corpus	O
smaller	O
by	O
combining	O
the	O
inputs	O
into	O
an	O
uncompressed	B-General_Concept
archive	O
(	O
such	O
as	O
a	O
tar	B-Application
file	I-Application
)	O
before	O
compression	O
because	O
of	O
mutual	O
information	O
between	O
the	O
text	B-General_Concept
files	I-General_Concept
.	O
</s>
<s>
This	O
method	O
was	O
used	O
in	O
a	O
benchmark	O
in	O
the	O
online	O
book	O
Data	B-General_Concept
Compression	I-General_Concept
Explained	O
by	O
Matt	O
Mahoney	O
.	O
</s>
<s>
The	O
table	O
below	O
shows	O
the	O
compressed	O
sizes	O
of	O
the	O
14	O
file	O
Calgary	B-General_Concept
corpus	I-General_Concept
using	O
both	O
methods	O
for	O
some	O
popular	O
compression	B-General_Concept
programs	I-General_Concept
.	O
</s>
<s>
The	O
"	O
Calgary	B-General_Concept
corpus	I-General_Concept
Compression	O
and	O
SHA-1	B-Algorithm
crack	O
Challenge	O
"	O
is	O
a	O
contest	O
started	O
by	O
Leonid	O
A	O
.	O
Broukhis	O
on	O
May	O
21	O
,	O
1996	O
to	O
compress	B-Device
the	O
14	O
file	O
version	O
of	O
the	O
Calgary	B-General_Concept
corpus	I-General_Concept
.	O
</s>
<s>
According	O
to	O
the	O
rules	O
of	O
the	O
contest	O
,	O
an	O
entry	O
must	O
consist	O
of	O
both	O
the	O
compressed	B-General_Concept
data	I-General_Concept
and	O
the	O
decompression	O
program	O
packed	O
into	O
one	O
of	O
several	O
standard	O
archive	O
formats	O
.	O
</s>
<s>
Currently	O
the	O
program	O
must	O
run	O
within	O
24	O
hours	O
on	O
a	O
2000	O
MIPS	O
machine	O
under	O
Windows	O
or	O
Linux	B-Application
and	O
use	O
less	O
than	O
800	O
MB	O
memory	O
.	O
</s>
<s>
An	O
SHA-1	B-Algorithm
challenge	O
was	O
later	O
added	O
.	O
</s>
<s>
It	O
allows	O
the	O
decompression	O
program	O
to	O
output	O
files	O
different	O
from	O
the	O
Calgary	B-General_Concept
corpus	I-General_Concept
as	O
long	O
as	O
they	O
hash	O
to	O
the	O
same	O
values	O
as	O
the	O
original	O
files	O
.	O
</s>
