<s>
GNU	B-Application
Chess	I-Application
is	O
a	O
free	B-Application
software	I-Application
chess	B-Application
engine	I-Application
and	O
command-line	B-Application
interface	I-Application
chessboard	O
.	O
</s>
<s>
The	O
goal	O
of	O
GNU	B-Application
Chess	I-Application
is	O
to	O
serve	O
as	O
a	O
basis	O
for	O
research	O
,	O
and	O
as	O
such	O
it	O
has	O
been	O
used	O
in	O
numerous	O
contexts	O
.	O
</s>
<s>
GNU	B-Application
Chess	I-Application
is	O
free	B-Application
software	I-Application
,	O
licensed	O
under	O
the	O
terms	O
of	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
version	O
3	O
or	O
any	O
later	O
version	O
,	O
and	O
is	O
maintained	O
by	O
collaborating	O
developers	O
.	O
</s>
<s>
As	O
one	O
of	O
the	O
earliest	O
computer	B-Application
chess	I-Application
programs	O
with	O
full	O
source	O
code	O
available	O
,	O
it	O
is	O
one	O
of	O
the	O
oldest	O
for	O
Unix-based	O
systems	O
and	O
has	O
since	O
been	O
ported	O
to	O
many	O
other	O
platforms	B-Device
.	O
</s>
<s>
GNU	B-Application
Chess	I-Application
6.2.5	O
is	O
rated	O
at	O
2661	O
Elo	O
points	O
on	O
CCRL	O
's	O
40-moves-in-2-minutes	O
list	O
.	O
</s>
<s>
On	O
the	O
same	O
list	O
,	O
Fritz	B-Application
8	I-Application
was	O
rated	O
at	O
2665	O
Elo	O
,	O
and	O
that	O
program	O
in	O
the	O
2004	O
Man	O
vs	O
Machine	O
World	O
Team	O
Championship	O
beat	O
grandmasters	O
Sergey	O
Karjakin	O
,	O
Veselin	O
Topalov	O
and	O
reached	O
a	O
draw	O
with	O
Ruslan	O
Ponomariov	O
.	O
</s>
<s>
It	O
is	O
often	O
used	O
in	O
conjunction	O
with	O
a	O
GUI	B-Application
program	O
such	O
as	O
XBoard	B-Application
or	O
GNOME	O
Chess	B-Application
,	O
where	O
it	O
is	O
included	O
as	O
the	O
default	O
engine	O
.	O
</s>
<s>
Initial	O
versions	O
of	O
XBoard	B-Application
's	O
Chess	B-Application
Engine	I-Application
Communication	O
Protocol	O
were	O
based	O
on	O
GNU	B-Application
Chess	I-Application
's	O
command-line	B-Application
interface	I-Application
.	O
</s>
<s>
Version	O
6	O
also	O
supports	O
the	O
Universal	B-General_Concept
Chess	I-General_Concept
Interface	I-General_Concept
(	O
UCI	O
)	O
.	O
</s>
<s>
Since	O
version	O
6.1	O
GNU	B-Application
chess	I-Application
supports	O
a	O
graphical	O
mode	O
for	O
terminal	O
emulators	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
GNU	B-Application
Chess	I-Application
was	O
written	O
by	O
Stuart	O
Cracraft	O
.	O
</s>
<s>
Having	O
started	O
in	O
1984	O
in	O
collaboration	O
with	O
Richard	O
Stallman	O
prior	O
to	O
his	O
founding	O
of	O
the	B-Application
GNU	I-Application
Project	I-Application
,	O
GNU	B-Application
Chess	I-Application
became	O
one	O
of	O
the	O
first	O
parts	O
of	O
GNU	B-Operating_System
.	O
</s>
<s>
GNU	B-Application
Chess	I-Application
has	O
been	O
enhanced	O
and	O
expanded	O
since	O
.	O
</s>
<s>
Version	O
5	O
of	O
GNU	B-Application
Chess	I-Application
was	O
based	O
on	O
the	O
Cobalt	O
chess	B-Application
engine	I-Application
written	O
by	O
Chua	O
Kong-Sian	O
.	O
</s>
<s>
In	O
2011	O
,	O
GNU	B-Application
Chess	I-Application
transitioned	O
to	O
version	O
6	O
,	O
which	O
is	O
based	O
on	O
Fabien	O
Letouzey	O
's	O
Fruit	B-Application
2.1	I-Application
chess	I-Application
engine	I-Application
.	O
</s>
<s>
According	O
to	O
CEGT	B-General_Concept
version	O
5.60	O
of	O
this	O
code	O
base	O
is	O
stronger	O
than	O
Fruit	O
2.3	O
,	O
the	O
latest	O
version	O
of	O
that	O
chess	B-Application
engine	I-Application
.	O
</s>
