<s>
In	O
computer	B-Application
chess	I-Application
,	O
a	O
chess	B-Application
engine	I-Application
is	O
a	O
computer	B-Application
program	I-Application
that	O
analyzes	O
chess	B-Application
or	O
chess	B-Application
variant	O
positions	O
,	O
and	O
generates	O
a	O
move	O
or	O
list	O
of	O
moves	O
that	O
it	O
regards	O
as	O
strongest	O
.	O
</s>
<s>
A	O
chess	B-Application
engine	I-Application
is	O
usually	O
a	O
back	B-Architecture
end	I-Architecture
with	O
a	O
command-line	B-Application
interface	I-Application
with	O
no	O
graphics	O
or	O
windowing	B-Application
.	O
</s>
<s>
Engines	O
are	O
usually	O
used	O
with	O
a	O
front	B-Architecture
end	I-Architecture
,	O
a	O
windowed	O
graphical	B-Application
user	I-Application
interface	I-Application
such	O
as	O
Chessbase	O
or	O
WinBoard	B-Application
that	O
the	O
user	O
can	O
interact	O
with	O
via	O
a	O
keyboard	O
,	O
mouse	O
or	O
touchscreen	O
.	O
</s>
<s>
Many	O
chess	B-Application
engines	I-Application
are	O
now	O
available	O
for	O
mobile	O
phones	O
and	O
tablets	O
,	O
making	O
them	O
even	O
more	O
accessible	O
.	O
</s>
<s>
The	O
meaning	O
of	O
the	O
term	O
"	O
chess	B-Application
engine	I-Application
"	O
has	O
evolved	O
over	O
time	O
.	O
</s>
<s>
In	O
1986	O
,	O
Linda	O
and	O
Tony	O
Scherzer	O
entered	O
their	O
program	O
Bebe	O
into	O
the	O
4th	O
World	O
Computer	B-Application
Chess	I-Application
Championship	O
,	O
running	O
it	O
on	O
"	O
Chess	B-Application
Engine	I-Application
,	O
"	O
their	O
brand	O
name	O
for	O
the	O
chess	B-Application
computer	I-Application
hardware	B-Architecture
made	O
,	O
and	O
marketed	O
by	O
their	O
company	O
Sys-10	O
,	O
Inc	O
.	O
By	O
1990	O
the	O
developers	O
of	O
Deep	B-General_Concept
Blue	I-General_Concept
,	O
Feng-hsiung	O
Hsu	O
and	O
Murray	O
Campbell	O
,	O
were	O
writing	O
of	O
giving	O
their	O
program	O
a	O
'	O
searching	O
engine	O
,	O
'	O
apparently	O
referring	O
to	O
the	O
software	O
rather	O
than	O
the	O
hardware	B-Architecture
.	O
</s>
<s>
In	O
December	O
1991	O
,	O
Computer-schach	O
&	O
Spiele	O
referred	O
to	O
Chessbase	O
's	O
recently	O
released	O
Fritz	B-Application
as	O
a	O
'	O
Schach-motor	O
,	O
'	O
the	O
German	O
translation	O
for	O
'	O
chess	B-Application
engine	I-Application
.	O
</s>
<s>
By	O
early	O
1993	O
,	O
Marty	O
Hirsch	O
was	O
drawing	O
a	O
distinction	O
between	O
commercial	O
chess	B-Application
programs	I-Application
such	O
as	O
Chessmaster	O
3000	O
or	O
Battle	B-Application
Chess	I-Application
on	O
the	O
one	O
hand	O
,	O
and	O
'	O
chess	B-Application
engines	I-Application
 '	I-Application
such	O
as	O
ChessGenius	B-Application
or	O
his	O
own	O
MChess	B-Application
Pro	I-Application
on	O
the	O
other	O
.	O
</s>
<s>
In	O
his	O
characterization	O
,	O
commercial	O
chess	B-Application
programs	I-Application
were	O
low	O
in	O
price	O
,	O
had	O
fancy	O
graphics	O
,	O
but	O
did	O
not	O
place	O
high	O
on	O
the	O
SSDF	O
(	O
Swedish	O
Chess	B-Application
Computer	I-Application
Association	O
)	O
rating	O
lists	O
while	O
engines	O
were	O
more	O
expensive	O
,	O
and	O
did	O
have	O
high	O
ratings	O
.	O
</s>
<s>
In	O
1994	O
,	O
Shay	B-Application
Bushinsky	I-Application
was	O
working	O
on	O
an	O
early	O
version	O
of	O
his	O
Junior	B-Application
program	O
.	O
</s>
<s>
He	O
wanted	O
to	O
focus	O
on	O
the	O
chess	B-Application
playing	O
part	O
rather	O
than	O
the	O
graphics	O
,	O
and	O
so	O
asked	O
Tim	O
Mann	O
how	O
he	O
could	O
get	O
Junior	B-Application
to	O
communicate	O
with	O
Winboard	B-Application
.	O
</s>
<s>
Tim	O
's	O
answer	O
formed	O
the	O
basis	O
for	O
what	O
became	O
known	O
as	O
the	O
Chess	B-Application
Engine	I-Application
Communication	O
Protocol	O
or	O
Winboard	B-Application
engines	O
,	O
originally	O
a	O
subset	O
of	O
the	O
GNU	B-Application
Chess	I-Application
command	B-Application
line	I-Application
interface	I-Application
.	O
</s>
<s>
It	O
also	O
mentions	O
three	O
"	O
graphical	B-Application
user	I-Application
interfaces	I-Application
"	O
(	O
GUI	B-Application
)	O
:	O
XBoard	B-Application
,	O
pgnRead	O
and	O
Slappy	O
the	O
database	O
.	O
</s>
<s>
In	O
2005	O
,	O
Michael	O
Adams	O
,	O
a	O
world	O
top	O
10	O
player	O
at	O
the	O
time	O
,	O
was	O
comprehensively	O
beaten	O
5½	O
-	O
½	O
by	O
Hydra	B-Architecture
,	O
drawing	O
only	O
one	O
of	O
the	O
six	O
games	O
.	O
</s>
<s>
Common	O
Winboard	B-Application
engines	O
would	O
include	O
Crafty	B-Application
,	O
ProDeo	B-Application
(	O
based	O
on	O
Rebel	B-Application
)	O
,	O
Chenard	O
,	O
Zarkov	O
and	O
Phalanx	O
.	O
</s>
<s>
Soon	O
after	O
,	O
they	O
added	O
the	O
engines	O
Junior	B-Application
and	O
Shredder	B-Application
to	O
their	O
product	O
line	O
up	O
,	O
including	O
engines	O
in	O
CB	O
protocol	O
as	O
separate	O
programs	O
which	O
could	O
be	O
installed	O
in	O
the	O
Chessbase	O
program	O
or	O
one	O
of	O
the	O
other	O
Fritz	B-Application
style	O
GUI	B-Application
's	O
.	O
</s>
<s>
Fritz	B-Application
1-14	O
were	O
only	O
issued	O
as	O
Chessbase	O
engines	O
,	O
while	O
Hiarcs	B-Application
,	O
Nimzo	O
,	O
Chess	B-Application
Tiger	I-Application
and	O
Crafty	B-Application
have	O
been	O
ported	O
to	O
Chessbase	O
format	O
even	O
though	O
they	O
were	O
UCI	B-General_Concept
or	O
Winboard	B-Application
engines	O
.	O
</s>
<s>
Recently	O
,	O
Chessbase	O
has	O
begun	O
to	O
include	O
Universal	B-General_Concept
Chess	I-General_Concept
Interface	I-General_Concept
(	O
UCI	B-General_Concept
)	O
engines	O
in	O
their	O
playing	O
programs	O
such	O
as	O
Komodo	B-Application
,	O
Houdini	B-Application
,	O
Fritz	B-Application
15	O
–	O
16	O
and	O
Rybka	B-Application
rather	O
than	O
convert	O
them	O
to	O
Chessbase	O
engines	O
.	O
</s>
<s>
In	O
2000	O
,	O
Stefan	O
Meyer-Kahlen	O
and	O
Franz	O
Huber	O
released	O
the	O
Universal	B-General_Concept
Chess	I-General_Concept
Interface	I-General_Concept
,	O
a	O
more	O
detailed	O
protocol	O
that	O
introduced	O
a	O
wider	O
set	O
of	O
features	O
.	O
</s>
<s>
Chessbase	O
soon	O
after	O
dropped	O
support	O
for	O
Winboard	B-Application
engines	O
,	O
and	O
added	O
support	O
for	O
UCI	B-General_Concept
to	O
their	O
engine	O
GUI	B-Application
's	O
and	O
Chessbase	O
programs	O
.	O
</s>
<s>
Most	O
of	O
the	O
top	O
engines	O
are	O
UCI	B-General_Concept
these	O
days	O
:	O
Stockfish	B-Application
,	O
Komodo	B-Application
,	O
Leela	B-Application
Chess	I-Application
Zero	I-Application
,	O
Houdini	B-Application
,	O
Fritz	B-Application
15-16	O
,	O
Rybka	B-Application
,	O
Shredder	B-Application
,	O
Fruit	B-Application
,	O
Critter	B-Application
,	O
Ivanhoe	B-Application
and	O
Ruffian	O
.	O
</s>
<s>
From	O
1998	O
,	O
the	O
German	O
company	O
Millenium	O
2000	O
briefly	O
moved	O
from	O
dedicated	O
chess	B-Application
computers	I-Application
into	O
the	O
software	O
market	O
,	O
developing	O
the	O
Millennium	O
Chess	B-Application
System	O
(	O
MCS	O
)	O
protocol	O
for	O
a	O
series	O
of	O
CD	O
's	O
containing	O
ChessGenius	B-Application
or	O
Shredder	B-Application
,	O
but	O
after	O
2001	O
ceased	O
releasing	O
new	O
software	O
.	O
</s>
<s>
A	O
more	O
longstanding	O
engine	O
protocol	O
has	O
been	O
used	O
by	O
the	O
Dutch	O
company	O
,	O
Lokasoft	O
,	O
which	O
eventually	O
took	O
over	O
the	O
marketing	O
of	O
Ed	B-Application
Schröder	I-Application
's	O
Rebel	B-Application
.	O
</s>
<s>
Chess	B-Application
engines	I-Application
increase	O
in	O
playing	O
strength	O
continually	O
.	O
</s>
<s>
A	O
chess	B-Application
engine	I-Application
often	O
uses	O
a	O
vast	O
previously	O
computed	O
opening	O
"	O
book	O
"	O
to	O
increase	O
its	O
playing	O
strength	O
for	O
the	O
first	O
several	O
moves	O
,	O
up	O
to	O
possibly	O
20	O
moves	O
or	O
more	O
in	O
deeply	O
analyzed	O
lines	O
.	O
</s>
<s>
Some	O
chess	B-Application
engines	I-Application
maintain	O
a	O
database	O
of	O
chess	B-Application
positions	O
,	O
along	O
with	O
previously	O
computed	O
evaluations	O
and	O
best	O
moves	O
,	O
in	O
effect	O
,	O
a	O
kind	O
of	O
"	O
dictionary	O
"	O
of	O
recurring	O
chess	B-Application
positions	O
.	O
</s>
<s>
Some	O
chess	B-Application
engines	I-Application
use	O
endgame	O
tablebases	O
to	O
increase	O
their	O
playing	O
strength	O
during	O
the	O
endgame	O
.	O
</s>
<s>
Such	O
tablebases	O
are	O
available	O
for	O
all	O
chess	B-Application
endgames	O
with	O
seven	O
pieces	O
or	O
fewer	O
(	O
trivial	O
endgame	O
positions	O
are	O
excluded	O
,	O
such	O
as	O
six	O
white	O
pieces	O
versus	O
a	O
lone	O
black	O
king	O
)	O
.	O
</s>
<s>
When	O
the	O
maneuvering	O
in	O
an	O
ending	O
to	O
achieve	O
an	O
irreversible	O
improvement	O
takes	O
more	O
moves	O
than	O
the	O
horizon	O
of	O
calculation	O
of	O
a	O
chess	B-Application
engine	I-Application
,	O
an	O
engine	O
is	O
not	O
guaranteed	O
to	O
find	O
the	O
best	O
move	O
without	O
the	O
use	O
of	O
an	O
endgame	O
tablebase	O
,	O
and	O
in	O
many	O
cases	O
can	O
fall	O
foul	O
of	O
the	O
fifty-move	O
rule	O
as	O
a	O
result	O
.	O
</s>
<s>
Distributed	B-Architecture
computing	I-Architecture
is	O
also	O
used	O
to	O
improve	O
the	O
software	B-Application
code	I-Application
of	O
chess	B-Application
engines	I-Application
.	O
</s>
<s>
In	O
2013	O
,	O
the	O
developers	O
of	O
the	O
Stockfish	B-Application
chess	B-Application
playing	O
program	O
started	O
using	O
distributed	B-Architecture
computing	I-Architecture
to	O
make	O
improvements	O
in	O
the	O
software	B-Application
code	I-Application
.	O
</s>
<s>
,	O
a	O
total	O
of	O
more	O
than	O
745	O
years	O
of	O
CPU	O
time	O
has	O
been	O
used	O
to	O
play	O
more	O
than	O
485	O
million	O
chess	B-Application
games	O
,	O
with	O
the	O
results	O
being	O
used	O
to	O
make	O
small	O
and	O
incremental	O
improvements	O
to	O
the	O
chess-playing	O
software	O
.	O
</s>
<s>
In	O
2019	O
,	O
Ethereal	O
author	O
Andrew	O
Grant	O
started	O
the	O
distributed	B-Architecture
computing	I-Architecture
testing	O
framework	O
OpenBench	O
,	O
based	O
upon	O
Stockfish	B-Application
's	O
testing	O
framework	O
,	O
and	O
it	O
is	O
now	O
the	O
most	O
widely-used	O
testing	O
framework	O
for	O
chess	B-Application
engines	I-Application
.	O
</s>
<s>
In	O
2000	O
,	O
when	O
Stefan	O
Meyer-Kahlen	O
and	O
Franz	O
Huber	O
released	O
the	O
Universal	B-General_Concept
Chess	I-General_Concept
Interface	I-General_Concept
protocol	O
they	O
included	O
the	O
parameters	O
uci_limitstrength	O
and	O
uci_elo	O
allowing	O
engine	O
authors	O
to	O
offer	O
a	O
variety	O
of	O
levels	O
rated	O
in	O
accordance	O
with	O
Elo	O
rating	O
,	O
as	O
calibrated	O
by	O
one	O
of	O
the	O
rating	O
lists	O
.	O
</s>
<s>
Most	O
GUIs	B-Application
for	O
UCI	B-General_Concept
engines	O
allow	O
users	O
to	O
set	O
this	O
Elo	O
rating	O
within	O
the	O
menus	O
.	O
</s>
<s>
Stockfish	B-Application
11	I-Application
)	O
.	O
</s>
<s>
Engines	O
which	O
have	O
a	O
uci_elo	O
parameter	O
include	O
Houdini	B-Application
,	O
Fritz	B-Application
15	O
–	O
16	O
,	O
Rybka	B-Application
,	O
Shredder	B-Application
,	O
Hiarcs	B-Application
,	O
Junior	B-Application
,	O
Zappa	B-Application
and	O
Sjeng	B-Application
.	O
</s>
<s>
GUI	B-Application
's	O
such	O
as	O
Shredder	B-Application
,	O
Chess	B-Application
Assistant	O
,	O
Convekta	O
Aquarium	O
,	O
Hiarcs	B-Application
Chess	B-Application
Explorer	O
or	O
Martin	O
Blume	O
's	O
Arena	O
have	O
dropdown	O
menus	O
for	O
setting	O
the	O
engine	O
's	O
uci_elo	O
parameter	O
.	O
</s>
<s>
The	O
Fritz	B-Application
family	O
GUI	B-Application
's	O
,	O
Chess	B-Application
Assistant	O
and	O
Aquarium	O
also	O
have	O
independent	O
means	O
of	O
limiting	O
an	O
engine	O
's	O
strength	O
apparently	O
based	O
on	O
an	O
engine	O
's	O
ability	O
to	O
generate	O
ranked	O
lists	O
of	O
moves	O
(	O
called	O
multipv	O
for	O
'	O
principle	O
variation	O
 '	O
)	O
.	O
</s>
<s>
The	O
results	O
of	O
computer	O
tournaments	O
give	O
one	O
view	O
of	O
the	O
relative	O
strengths	O
of	O
chess	B-Application
engines	I-Application
.	O
</s>
<s>
However	O
,	O
tournaments	O
do	O
not	O
play	O
a	O
statistically	B-General_Concept
significant	I-General_Concept
number	O
of	O
games	O
for	O
accurate	O
strength	O
determination	O
.	O
</s>
<s>
Most	O
tournaments	O
also	O
allow	O
any	O
types	O
of	O
hardware	B-Architecture
,	O
so	O
only	O
engine/hardware	O
combinations	O
are	O
being	O
compared	O
.	O
</s>
<s>
If	O
an	O
amateur	O
engine	O
wins	O
a	O
tournament	O
or	O
otherwise	O
performs	O
well	O
(	O
for	O
example	O
,	O
Zappa	B-Application
in	O
2005	O
)	O
,	O
then	O
it	O
is	O
quickly	O
commercialized	O
.	O
</s>
<s>
However	O
,	O
after	O
the	O
rise	O
of	O
volunteer	B-Operating_System
distributed	B-Architecture
computing	I-Architecture
projects	O
such	O
as	O
Leela	B-Application
Chess	I-Application
Zero	I-Application
and	O
Stockfish	B-Application
and	O
testing	O
frameworks	O
such	O
as	O
FishTest	O
and	O
OpenBench	O
in	O
the	O
late	O
2010s	O
,	O
free	B-License
and	I-License
open	I-License
source	I-License
programs	O
have	O
largely	O
displaced	O
commercial	O
programs	O
as	O
the	O
strongest	O
engines	O
in	O
tournaments	O
.	O
</s>
<s>
Chess	B-Application
engine	I-Application
rating	O
lists	O
aim	O
to	O
provide	O
statistically	B-General_Concept
significant	I-General_Concept
measures	O
of	O
relative	O
engine	O
strength	O
.	O
</s>
<s>
Some	O
also	O
standardize	O
the	O
opening	O
books	O
,	O
the	O
time	O
controls	O
,	O
and	O
the	O
computer	B-Architecture
hardware	I-Architecture
the	O
engines	O
use	O
,	O
in	O
an	O
attempt	O
to	O
measure	O
the	O
strength	O
differences	O
of	O
the	O
engines	O
only	O
.	O
</s>
<s>
The	O
ratings	O
on	O
the	O
rating	O
lists	O
,	O
although	O
calculated	O
by	O
using	O
the	O
Elo	O
system	O
(	O
or	O
similar	O
rating	O
methods	O
)	O
,	O
have	O
no	O
direct	O
relation	O
to	O
FIDE	O
Elo	O
ratings	O
or	O
to	O
other	O
chess	B-Application
federation	O
ratings	O
of	O
human	O
players	O
.	O
</s>
<s>
Missing	O
from	O
many	O
rating	O
lists	O
are	O
IPPOLIT	B-Application
and	O
its	O
derivatives	O
.	O
</s>
<s>
Although	O
very	O
strong	O
and	O
open	B-License
source	I-License
,	O
there	O
are	O
allegations	O
from	O
commercial	O
software	O
interests	O
that	O
they	O
were	O
derived	O
from	O
a	O
disassembled	O
binary	O
of	O
Rybka	B-Application
.	O
</s>
<s>
Rybka	B-Application
in	O
turn	O
was	O
accused	O
of	O
being	O
based	O
on	O
Fruit	B-Application
,	O
and	O
in	O
June	O
2011	O
,	O
the	O
ICGA	O
formally	O
claimed	O
Rybka	B-Application
was	O
derived	O
from	O
Fruit	B-Application
and	O
Crafty	B-Application
and	O
banned	O
Rybka	B-Application
from	O
the	O
International	O
Computer	O
Games	O
Association	O
World	O
Computer	B-Application
Chess	I-Application
Championship	O
,	O
and	O
revoked	O
its	O
previous	O
victories	O
(	O
2007	O
,	O
2008	O
,	O
2009	O
,	O
and	O
2010	O
)	O
.	O
</s>
<s>
Despite	O
all	O
this	O
,	O
Rybka	B-Application
is	O
still	O
included	O
on	O
many	O
rating	O
lists	O
,	O
such	O
as	O
CCRL	O
and	O
CEGT	B-General_Concept
,	O
in	O
addition	O
to	O
Houdini	B-Application
,	O
a	O
derivative	O
of	O
the	O
IPPOLIT	B-Application
derivative	O
Robbolito	O
,	O
and	O
Fire	O
,	O
a	O
derivative	O
of	O
Houdini	B-Application
.	O
</s>
<s>
In	O
addition	O
,	O
Fat	O
Fritz	B-Application
2	O
,	O
a	O
derivative	O
of	O
Stockfish	B-Application
,	O
is	O
also	O
included	O
on	O
most	O
of	O
the	O
rating	O
lists	O
.	O
</s>
<s>
There	O
are	O
a	O
number	O
of	O
factors	O
that	O
vary	O
among	O
the	O
chess	B-Application
engine	I-Application
rating	O
lists	O
:	O
</s>
<s>
More	O
games	O
when	O
testing	O
each	O
engine	O
result	O
in	O
higher	O
statistical	B-General_Concept
significance	I-General_Concept
.	O
</s>
<s>
Longer	O
time	O
controls	O
are	O
better	O
suited	O
for	O
determining	O
tournament	O
play	O
strength	O
,	O
but	O
also	O
either	O
make	O
testing	O
more	O
time-consuming	O
or	O
the	O
results	O
less	O
statistically	B-General_Concept
significant	I-General_Concept
.	O
</s>
<s>
The	O
latter	O
results	O
in	O
a	O
smaller	O
statistical	B-General_Concept
significance	I-General_Concept
than	O
the	O
former	O
because	O
different	O
time	O
controls	O
is	O
a	O
potential	O
confounder	O
.	O
</s>
<s>
Hardware	B-Architecture
used	O
:	O
</s>
<s>
Faster	O
hardware	B-Architecture
with	O
more	O
memory	O
leads	O
to	O
stronger	O
play	O
.	O
</s>
<s>
Hardware	B-Architecture
using	O
modern	O
instruction	O
sets	O
such	O
as	O
AVX2	O
or	O
AVX512	B-General_Concept
favor	O
engines	O
using	O
vectors	O
and	O
vector	O
intrinsics	O
in	O
their	O
code	O
,	O
common	O
in	O
neural	B-Architecture
networks	I-Architecture
.	O
</s>
<s>
Graphics	B-Architecture
processing	I-Architecture
units	I-Architecture
favor	O
programs	O
with	O
deep	O
neural	B-Architecture
networks	I-Architecture
.	O
</s>
<s>
Multiprocessor	O
vs.	O
single	O
processor	O
hardware	B-Architecture
.	O
</s>
<s>
Consistent	O
hardware	B-Architecture
throughout	O
the	O
rating	O
list	O
vs	O
different	O
hardware	B-Architecture
for	O
every	O
test	O
.	O
</s>
<s>
The	O
latter	O
results	O
in	O
a	O
smaller	O
statistical	B-General_Concept
significance	I-General_Concept
than	O
the	O
former	O
because	O
different	O
hardware	B-Architecture
is	O
a	O
potential	O
confounder	O
.	O
</s>
<s>
This	O
is	O
particularly	O
problematic	O
for	O
CEGT	B-General_Concept
because	O
multiple	O
testers	O
each	O
with	O
their	O
own	O
unique	O
hardware	B-Architecture
are	O
involved	O
in	O
testing	O
each	O
engine	O
in	O
CEGT	B-General_Concept
.	O
</s>
<s>
The	O
Nolot	B-General_Concept
test	I-General_Concept
suite	I-General_Concept
,	O
for	O
instance	O
,	O
focuses	O
on	O
deep	O
sacrifices	O
.	O
</s>
<s>
The	O
BT2450	O
and	O
BT2630	O
test	O
suites	O
measure	O
the	O
tactical	O
capability	O
of	O
a	O
chess	B-Application
engine	I-Application
and	O
have	O
been	O
used	O
by	O
REBEL	B-Application
.	O
</s>
<s>
There	O
is	O
also	O
a	O
general	O
test	O
suite	O
called	O
Brilliancy	O
which	O
was	O
compiled	O
mostly	O
from	O
How	O
to	O
Reassess	O
Your	O
Chess	B-Application
Workbook	O
.	O
</s>
<s>
Another	O
modern	O
test	O
suite	O
is	O
Nightmare	O
II	O
which	O
contains	O
30	O
chess	B-Application
puzzles	O
.	O
</s>
<s>
In	O
1999	O
,	O
Garry	O
Kasparov	O
played	O
a	O
chess	B-Application
game	O
called	O
"	O
Kasparov	O
versus	O
the	O
World	O
"	O
over	O
the	O
Internet	O
,	O
hosted	O
by	O
the	O
MSN	B-Application
Gaming	I-Application
Zone	I-Application
.	O
</s>
<s>
Both	O
sides	O
used	O
computer	O
(	O
chess	B-Application
engine	I-Application
)	O
assistance	O
.	O
</s>
<s>
The	O
game	O
lasted	O
four	O
months	O
,	O
ending	O
after	O
Kasparov	O
's	O
62nd	O
move	O
when	O
he	O
announced	O
a	O
forced	O
checkmate	B-Application
in	O
28	O
moves	O
found	O
with	O
the	O
computer	B-Application
program	I-Application
Deep	B-Application
Junior	I-Application
.	O
</s>
<s>
After	O
the	O
game	O
,	O
Kasparov	O
said	O
:	O
"	O
It	O
is	O
the	O
greatest	O
game	O
in	O
the	O
history	O
of	O
chess	B-Application
.	O
</s>
<s>
The	O
sheer	O
number	O
of	O
ideas	O
,	O
the	O
complexity	O
,	O
and	O
the	O
contribution	O
it	O
has	O
made	O
to	O
chess	B-Application
make	O
it	O
the	O
most	O
important	O
game	O
ever	O
played.	O
"	O
</s>
<s>
Some	O
chess	B-Application
engines	I-Application
have	O
been	O
developed	O
to	O
play	O
chess	B-Application
variants	O
,	O
adding	O
the	O
necessary	O
code	O
to	O
simulate	O
non-standard	O
chess	B-Application
pieces	O
,	O
or	O
to	O
analyze	O
play	O
on	O
non-standard	O
boards	O
.	O
</s>
<s>
ChessV	B-Application
and	O
Fairy-Max	B-Application
,	O
for	O
example	O
,	O
are	O
both	O
capable	O
of	O
playing	O
variants	O
on	O
a	O
chessboard	O
up	O
to	O
12×8	O
in	O
size	O
,	O
such	O
as	O
Capablanca	O
Chess	B-Application
(	O
10×8	O
board	O
)	O
.	O
</s>
<s>
For	O
larger	O
boards	O
,	O
however	O
,	O
there	O
are	O
few	O
chess	B-Application
engines	I-Application
that	O
can	O
play	O
effectively	O
,	O
and	O
indeed	O
chess	B-Application
games	O
played	O
on	O
an	O
unbounded	O
chessboard	O
(	O
infinite	O
chess	B-Application
)	O
are	O
virtually	O
untouched	O
by	O
chess-playing	O
software	O
,	O
although	O
theoretically	O
a	O
program	O
using	O
a	O
MuZero-derived	O
algorithm	O
could	O
handle	O
an	O
unbounded	O
state	O
space	O
.	O
</s>
<s>
XBoard/Winboard	O
was	O
one	O
of	O
the	O
earliest	O
graphical	B-Application
user	I-Application
interfaces	I-Application
(	O
GUI	B-Application
)	O
.	O
</s>
<s>
Tim	O
Mann	O
created	O
it	O
to	O
provide	O
a	O
GUI	B-Application
for	O
the	O
GNU	B-Application
Chess	I-Application
engine	O
,	O
but	O
after	O
that	O
,	O
other	O
engines	O
such	O
as	O
Crafty	B-Application
appeared	O
which	O
used	O
the	O
Winboard	B-Application
protocol	O
.	O
</s>
<s>
Eventually	O
,	O
the	O
program	O
Chessmaster	O
included	O
the	O
option	O
to	O
import	O
other	O
Winboard	B-Application
engines	O
in	O
addition	O
to	O
the	O
King	O
engine	O
which	O
was	O
included	O
.	O
</s>
<s>
In	O
1995	O
,	O
Chessbase	O
began	O
offering	O
the	O
Fritz	B-Application
engine	O
as	O
a	O
separate	O
program	O
within	O
the	O
Chessbase	O
database	O
program	O
and	O
within	O
the	O
Fritz	B-Application
GUI	B-Application
.	O
</s>
<s>
Soon	O
after	O
,	O
they	O
added	O
the	O
Junior	B-Application
and	O
Shredder	B-Application
engines	O
to	O
their	O
product	O
line	O
up	O
,	O
packaging	O
them	O
within	O
the	O
same	O
GUI	B-Application
as	O
was	O
used	O
for	O
Fritz	B-Application
.	O
</s>
<s>
In	O
the	O
late	O
1990s	O
,	O
the	O
Fritz	B-Application
GUI	B-Application
was	O
able	O
to	O
run	O
Winboard	B-Application
engines	O
via	O
an	O
adapter	O
,	O
but	O
after	O
2000	O
,	O
Chessbase	O
simply	O
added	O
support	O
for	O
UCI	B-General_Concept
engines	O
,	O
and	O
no	O
longer	O
invested	O
much	O
effort	O
in	O
Winboard	B-Application
.	O
</s>
<s>
In	O
2000	O
,	O
Stefan	O
Meyer-Kahlen	O
started	O
selling	O
Shredder	B-Application
in	O
a	O
separate	O
UCI	B-General_Concept
GUI	B-Application
of	O
his	O
own	O
design	O
,	O
allowing	O
UCI	B-General_Concept
or	O
Winboard	B-Application
engines	O
to	O
be	O
imported	O
into	O
it	O
.	O
</s>
<s>
Convekta	O
's	O
Chess	B-Application
Assistant	O
and	O
Lokasoft	O
's	O
ChessPartner	O
also	O
added	O
the	O
ability	O
to	O
import	O
Winboard	B-Application
and	O
UCI	B-General_Concept
engines	O
into	O
their	O
products	O
.	O
</s>
<s>
Shane	O
Hudson	O
developed	O
Shane	B-Language
's	I-Language
Chess	I-Language
Information	I-Language
Database	I-Language
,	O
a	O
free	O
GUI	B-Application
for	O
Linux	O
,	O
Mac	O
and	O
Windows	O
.	O
</s>
<s>
Martin	O
Blume	O
developed	O
Arena	O
,	O
another	O
free	O
GUI	B-Application
for	O
Linux	O
and	O
Windows	O
.	O
</s>
<s>
Lucas	O
Monge	O
entered	O
the	O
field	O
with	O
the	O
free	O
Lucas	O
Chess	B-Application
GUI	B-Application
.	O
</s>
<s>
All	O
three	O
can	O
handle	O
both	O
UCI	B-General_Concept
and	O
Winboard	B-Application
engines	O
.	O
</s>
<s>
On	O
Android	O
,	O
Aart	O
Bik	O
came	O
out	O
with	O
Chess	B-Application
for	O
Android	O
,	O
another	O
free	O
GUI	B-Application
,	O
and	O
Gerhard	O
Kalab	O
's	O
Chess	B-Application
PGN	O
Master	O
and	O
Peter	O
Osterlund	O
's	O
Droidfish	O
can	O
also	O
serve	O
as	O
GUIs	B-Application
for	O
engines	O
.	O
</s>
<s>
The	O
Computer	B-Application
Chess	I-Application
Wiki	O
lists	O
many	O
chess	B-Application
GUIs	B-Application
.	O
</s>
