<s>
Dr.Fill	B-Application
is	O
a	O
computer	B-Application
program	I-Application
that	O
solves	O
American-style	O
crossword	O
puzzles	O
.	O
</s>
<s>
It	O
was	O
developed	O
by	O
Matt	O
Ginsberg	O
and	O
described	O
by	O
Ginsberg	O
in	O
an	O
article	O
in	O
the	O
Journal	O
of	O
Artificial	B-Application
Intelligence	I-Application
Research	I-Application
.	O
</s>
<s>
Ginsberg	O
claims	O
in	O
that	O
article	O
that	O
Dr.Fill	B-Application
is	O
among	O
the	O
top	O
fifty	O
crossword	O
solvers	O
in	O
the	O
world	O
.	O
</s>
<s>
As	O
described	O
by	O
Ginsberg	O
,	O
Dr.Fill	B-Application
works	O
by	O
converting	O
a	O
crossword	O
to	O
a	O
weighted	O
constraint	B-Application
satisfaction	I-Application
problem	I-Application
and	O
then	O
attempting	O
to	O
maximize	O
the	O
probability	O
that	O
the	O
fill	O
is	O
correct	O
.	O
</s>
<s>
Probabilities	O
for	O
individual	O
words	O
or	O
phrases	O
in	O
the	O
puzzle	O
are	O
computed	O
using	O
relatively	O
simple	O
statistical	O
techniques	O
based	O
on	O
features	O
such	O
as	O
previous	O
appearances	O
of	O
the	O
clue	O
,	O
number	O
of	O
Google	B-Application
hits	I-Application
for	O
the	O
fill	O
,	O
and	O
so	O
on	O
.	O
</s>
<s>
In	O
doing	O
this	O
,	O
Dr.Fill	B-Application
is	O
attempting	O
to	O
solve	O
a	O
problem	O
similar	O
to	O
that	O
tackled	O
by	O
the	O
Jeopardy	O
!	O
-playing	O
program	O
Watson	B-Application
;	O
Dr.Fill	B-Application
runs	O
on	O
a	O
laptop	O
instead	O
of	O
a	O
supercomputer	O
and	O
Ginsberg	O
remarks	O
that	O
Watson	B-Application
is	O
far	O
more	O
effective	O
than	O
Dr.Fill	B-Application
at	O
solving	O
this	O
portion	O
of	O
the	O
problem	O
.	O
</s>
<s>
Instead	O
of	O
computational	O
horsepower	O
,	O
Dr.Fill	B-Application
relies	O
on	O
the	O
constraints	O
provided	O
by	O
crossing	O
words	O
to	O
refine	O
its	O
answers	O
.	O
</s>
<s>
A	O
variety	O
of	O
techniques	O
from	O
artificial	B-Application
intelligence	I-Application
are	O
applied	O
to	O
attempt	O
to	O
find	O
the	O
most	O
likely	O
fill	O
.	O
</s>
<s>
Ginsberg	O
remarks	O
that	O
postprocessing	O
was	O
chosen	O
over	O
branch	B-Algorithm
and	I-Algorithm
bound	I-Algorithm
because	O
the	O
two	O
techniques	O
are	O
mutually	O
incompatible	O
and	O
postprocessing	O
was	O
found	O
to	O
be	O
more	O
effective	O
in	O
this	O
domain	O
.	O
</s>
<s>
Dr.Fill	B-Application
participated	O
in	O
the	O
2012	O
American	O
Crossword	O
Puzzle	O
Tournament	O
,	O
finishing	O
141st	O
of	O
approximately	O
650	O
entrants	O
with	O
a	O
total	O
score	O
of	O
just	O
over	O
10,000	O
points	O
.	O
</s>
<s>
The	O
appearance	O
led	O
to	O
a	O
variety	O
of	O
descriptions	O
of	O
Dr.Fill	B-Application
in	O
the	O
popular	O
press	O
,	O
including	O
The	O
Economist	O
,	O
the	O
San	O
Francisco	O
Chronicle	O
and	O
Gizmodo	O
.	O
</s>
<s>
A	O
description	O
of	O
Dr.Fill	B-Application
appeared	O
on	O
the	O
front	O
page	O
of	O
the	O
March	O
17	O
,	O
2012	O
New	O
York	O
Times	O
.	O
</s>
<s>
Dr.Fill	B-Application
'	O
s	O
score	O
in	O
2013	O
improved	O
to	O
10	O
,	O
550	O
,	O
which	O
would	O
have	O
earned	O
it	O
92nd	O
place	O
.	O
</s>
<s>
Videos	O
of	O
the	O
program	O
solving	O
the	O
problems	O
from	O
the	O
tournament	O
are	O
available	O
on	O
YouTube	B-General_Concept
.	I-General_Concept
</s>
<s>
A	O
video	O
of	O
the	O
program	O
solving	O
the	O
first	O
six	O
puzzles	O
from	O
that	O
tournament	O
,	O
together	O
with	O
a	O
talk	O
given	O
by	O
Ginsberg	O
describing	O
its	O
performance	O
,	O
can	O
be	O
found	O
on	O
YouTube	B-General_Concept
.	I-General_Concept
</s>
<s>
Dr.Fill	B-Application
has	O
largely	O
continued	O
to	O
improve	O
since	O
the	O
2014	O
event	O
.	O
</s>
<s>
Dr.Fill	B-Application
returned	O
to	O
"	O
form	O
"	O
in	O
2019	O
,	O
once	O
again	O
scoring	O
11,795	O
and	O
finishing	O
in	O
14th	O
place	O
.	O
</s>
<s>
The	O
2020	O
ACPT	O
was	O
cancelled	O
due	O
to	O
COVID-19	O
,	O
and	O
Dr.Fill	B-Application
participated	O
as	O
a	O
non-competitor	O
in	O
the	O
Boswords	O
tournament	O
instead	O
.	O
</s>
<s>
The	O
Dr.Fill	B-Application
effort	O
was	O
joined	O
by	O
the	O
Berkeley	O
NLP	O
Group	O
,	O
creating	O
a	O
hybrid	O
system	O
named	O
Berkeley	O
Crossword	O
Solver	O
,	O
and	O
Dr.Fill	B-Application
won	O
the	O
main	O
event	O
,	O
scoring	O
12,825	O
points	O
with	O
Erik	O
Agard	O
,	O
the	O
highest	O
scoring	O
human	O
,	O
scoring	O
12,810	O
points	O
.	O
</s>
<s>
Dr.Fill	B-Application
also	O
completed	O
that	O
puzzle	O
perfectly	O
,	O
but	O
in	O
49	O
seconds	O
.	O
</s>
<s>
After	O
winning	O
the	O
tournament	O
,	O
Ginsberg	O
announced	O
on	O
August	O
8	O
,	O
2021	O
,	O
that	O
both	O
he	O
and	O
Dr.Fill	B-Application
would	O
be	O
retiring	O
from	O
crosswords	O
.	O
</s>
