<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
anytime	B-Algorithm
A*	I-Algorithm
is	O
a	O
family	O
of	O
variants	O
of	O
the	O
A*	B-Protocol
search	I-Protocol
algorithm	I-Protocol
.	O
</s>
<s>
Like	O
other	O
anytime	B-Algorithm
algorithms	I-Algorithm
,	O
it	O
has	O
a	O
flexible	O
time	O
cost	O
,	O
can	O
return	O
a	O
valid	O
solution	O
to	O
a	O
pathfinding	B-Algorithm
or	O
graph	B-Algorithm
traversal	I-Algorithm
problem	O
even	O
if	O
it	O
is	O
interrupted	O
before	O
it	O
ends	O
,	O
by	O
generating	O
a	O
fast	O
,	O
non-optimal	O
solution	O
before	O
progressively	O
optimizing	O
it	O
.	O
</s>
<s>
This	O
ability	O
to	O
quickly	O
generate	O
solutions	O
has	O
made	O
it	O
attractive	O
to	O
Search-base	O
sites	O
and	O
AI	B-Application
designs	O
.	O
</s>
<s>
Running	O
the	O
optimal	O
A*	B-Protocol
algorithm	I-Protocol
to	O
completion	O
is	O
too	O
expensive	O
for	O
many	O
purposes	O
.	O
</s>
<s>
Iteratively	O
reducing	O
the	O
degree	O
the	O
heuristic	O
is	O
"	O
inflated	O
"	O
provides	O
a	O
naive	O
anytime	B-Algorithm
algorithm	I-Algorithm
(	O
ATA*	O
,	O
2002	O
)	O
,	O
but	O
this	O
repeats	O
previous	O
work	O
.	O
</s>
<s>
A	O
dynamic	O
(	O
in	O
the	O
sense	O
of	O
D*	B-Algorithm
)	O
modification	O
of	O
ARA*	O
,	O
Anytime	O
Dynamic	O
A*	O
(	O
ADA*	O
)	O
was	O
published	O
in	O
2005	O
.	O
</s>
<s>
It	O
combines	O
aspects	O
of	O
D*	B-Algorithm
Lite	O
and	O
ARA*	O
.	O
</s>
<s>
A*	B-Protocol
search	I-Protocol
algorithm	I-Protocol
can	O
be	O
presented	O
by	O
the	O
function	O
of	O
,	O
where	O
is	O
the	O
last	O
node	O
on	O
the	O
path	O
,	O
is	O
the	O
cost	O
of	O
the	O
path	O
from	O
the	O
start	O
node	O
to	O
,	O
and	O
is	O
a	O
heuristic	O
that	O
estimates	O
the	O
cost	O
of	O
the	O
cheapest	O
path	O
from	O
to	O
the	O
goal	O
.	O
</s>
<s>
Different	O
than	O
the	O
A*	B-Protocol
algorithm	I-Protocol
,	O
the	O
most	O
important	O
function	O
of	O
Anytime	B-Algorithm
A*	B-Protocol
algorithm	I-Protocol
is	O
that	O
,	O
they	O
can	O
be	O
stopped	O
and	O
then	O
can	O
be	O
restarted	O
at	O
any	O
time	O
.	O
</s>
<s>
Anytime	B-Algorithm
A*	I-Algorithm
family	O
of	O
algorithms	O
typically	O
build	O
upon	O
the	O
weighted	O
version	O
of	O
the	O
A*	B-Protocol
search	I-Protocol
:	O
where	O
one	O
uses	O
,	O
,	O
and	O
performs	O
the	O
A*	B-Protocol
search	I-Protocol
as	O
usual	O
,	O
which	O
eventually	O
happens	O
faster	O
since	O
fewer	O
nodes	O
are	O
expanded	O
.	O
</s>
<s>
Anytime	O
weighted	O
A*	O
turns	O
weighted	O
A*	O
into	O
an	O
anytime	B-Algorithm
algorithm	I-Algorithm
as	O
follows	O
.	O
</s>
