<s>
Houdini	B-Application
is	O
a	O
UCI	B-General_Concept
chess	B-Application
engine	I-Application
developed	O
by	O
Belgian	O
programmer	B-General_Concept
Robert	O
Houdart	O
.	O
</s>
<s>
It	O
is	O
influenced	O
by	O
open-source	B-Application
engines	O
IPPOLIT/RobboLito	O
,	O
Stockfish	B-Application
,	O
and	O
Crafty	B-Application
.	O
</s>
<s>
Chess	O
commentator	O
and	O
video	O
annotator	O
CM	O
Tryfon	O
Gavriel	O
compared	O
Houdini	B-Application
's	O
playing	O
style	O
to	O
that	O
of	O
the	O
Romantic	O
Era	O
of	O
chess	O
,	O
where	O
an	O
attacking	O
,	O
sacrificial	O
style	O
was	O
predominant	O
.	O
</s>
<s>
According	O
to	O
Robert	O
Houdart	O
,	O
Houdini	B-Application
's	O
advantage	O
against	O
other	O
top	O
engines	O
is	O
in	O
its	O
handling	O
of	O
piece	O
mobility	O
,	O
which	O
is	O
why	O
it	O
"	O
favors	O
aggressive	O
play	O
that	O
tries	O
to	O
win	O
the	O
game	O
"	O
.	O
</s>
<s>
Work-around	O
for	O
Shredder	O
GUI	B-Application
.	O
</s>
<s>
1.5a	O
Maintenance	O
update	O
with	O
work-arounds	O
for	O
Fritz	O
GUI	B-Application
and	O
other	O
minor	O
improvements	O
.	O
</s>
<s>
Houdini	B-Application
Pro	O
version	O
for	O
high-end	O
users	O
with	O
powerful	O
hardware	O
(	O
multi-core	B-Architecture
support	O
)	O
.	O
</s>
<s>
UCI_Elo	O
and	O
UCI_LimitStrength	O
options	O
as	O
UCI	B-General_Concept
standard-compliant	O
alternative	O
to	O
Strength	O
option	O
.	O
</s>
<s>
Exit	O
on	O
detection	O
with	O
GUI	B-Application
exit	O
.	O
</s>
<s>
The	O
latest	O
stable	O
release	O
of	O
Houdini	B-Application
comes	O
in	O
two	O
versions	O
:	O
Houdini	B-Application
6	O
Standard	O
and	O
Houdini	B-Application
6	O
Pro	O
.	O
</s>
<s>
Houdini	B-Application
6	O
Pro	O
supports	O
up	O
to	O
128	O
processor	O
cores	B-Architecture
,	O
128GB	O
of	O
RAM	B-Architecture
(	O
hash	O
)	O
and	O
is	O
NUMA-aware	O
,	O
Houdini	B-Application
5	O
Standard	O
only	O
supports	O
up	O
to	O
8	O
processor	O
cores	B-Architecture
,	O
4GB	O
of	O
hash	O
and	O
is	O
not	O
NUMA-aware	O
.	O
</s>
<s>
As	O
with	O
many	O
other	O
UCI	B-General_Concept
engines	O
,	O
Houdini	B-Application
comes	O
with	O
no	O
GUI	B-Application
,	O
so	O
a	O
chess	O
GUI	B-Application
is	O
needed	O
for	O
running	O
the	O
engine	O
.	O
</s>
<s>
Houdini	B-Application
5	O
uses	O
calibrated	O
evaluations	O
in	O
which	O
engine	O
scores	O
correlate	O
directly	O
with	O
the	O
win	O
expectancy	O
in	O
the	O
position	O
.	O
</s>
<s>
Houdini	B-Application
has	O
had	O
a	O
history	O
of	O
allegations	O
against	O
it	O
that	O
it	O
contains	O
code	O
from	O
other	O
engines	O
.	O
</s>
<s>
Houdini	B-Application
1.0	I-Application
has	O
been	O
alleged	O
to	O
be	O
an	O
IPPOLIT	B-Application
derivative	O
,	O
and	O
to	O
have	O
plagiarized	O
from	O
Rybka	B-Application
,	O
which	O
initially	O
lead	O
to	O
Houdini	B-Application
1.0	I-Application
to	O
not	O
be	O
tested	O
in	O
any	O
rating	O
lists	O
such	O
as	O
CCRL	O
and	O
CEGT	B-General_Concept
.	O
</s>
<s>
Houdini	B-Application
5.0	O
and	O
Houdini	B-Application
6.0	O
have	O
been	O
alleged	O
to	O
be	O
Stockfish	B-Application
8	O
derivatives	O
without	O
providing	O
the	O
sources	O
on	O
request	O
,	O
and	O
thus	O
,	O
violating	O
the	O
GPL	B-License
license	I-License
.	O
</s>
<s>
This	O
has	O
resulted	O
in	O
TCEC	O
revoking	O
Houdini	B-Application
's	O
championship	O
results	O
,	O
and	O
disallowing	O
Houdini	B-Application
from	O
competing	O
.	O
</s>
<s>
Leaked	O
source	O
code	O
has	O
seemingly	O
been	O
shown	O
to	O
produce	O
almost	O
identical	O
play	O
to	O
Houdini	B-Application
5.0	O
and	O
Houdini	B-Application
6.0	O
,	O
while	O
containing	O
direct	O
references	O
to	O
Stockfish	B-Application
in	O
the	O
code	O
documentation	O
.	O
</s>
<s>
On	O
20	O
July	O
2021	O
,	O
the	O
Stockfish	B-Application
team	O
announced	O
legal	O
action	O
against	O
ChessBase	O
alleging	O
that	O
Houdini	B-Application
6	O
and	O
Fat	O
Fritz	O
2	O
were	O
in	O
violation	O
of	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
license	O
.	O
</s>
<s>
Houdini	B-Application
6.0	O
is	O
also	O
no	O
longer	O
available	O
on	O
ChessBase	O
's	O
website	O
due	O
to	O
it	O
being	O
a	O
Stockfish	B-Application
derivative	O
.	O
</s>
<s>
Houdini	B-Application
used	O
to	O
be	O
one	O
of	O
the	O
most	O
successful	O
engines	O
in	O
TCEC	O
,	O
with	O
three	O
championship	O
wins	O
to	O
date	O
,	O
but	O
since	O
season	O
18	O
it	O
no	O
longer	O
participates	O
in	O
TCEC	O
due	O
to	O
it	O
plagiarized	O
code	O
(	O
see	O
Controversies	O
)	O
.	O
</s>
<s>
Houdini	B-Application
plays	O
a	O
pawn	O
sacrifice	O
on	O
move	O
43	O
.	O
</s>
