<s>
The	O
blocks	B-General_Concept
world	I-General_Concept
is	O
a	O
planning	B-Application
domain	I-Application
in	O
artificial	B-Application
intelligence	I-Application
.	I-Application
</s>
<s>
The	O
simplicity	O
of	O
this	O
toy	O
world	O
lends	O
itself	O
readily	O
to	O
classical	O
symbolic	B-General_Concept
artificial	I-General_Concept
intelligence	I-General_Concept
approaches	O
,	O
in	O
which	O
the	O
world	O
is	O
modeled	O
as	O
a	O
set	O
of	O
abstract	O
symbols	O
which	O
may	O
be	O
reasoned	O
about	O
.	O
</s>
<s>
Artificial	B-Application
Intelligence	I-Application
can	O
be	O
researched	O
in	O
theory	O
and	O
with	O
practical	O
applications	O
.	O
</s>
<s>
The	O
problem	O
with	O
most	O
practical	O
application	O
is	O
,	O
that	O
the	O
engineers	O
do	O
n't	O
know	O
how	O
to	O
program	O
an	O
AI	B-Application
system	O
.	O
</s>
<s>
Toy	O
problems	O
were	O
invented	O
with	O
the	O
aim	O
to	O
program	O
an	O
AI	B-Application
which	O
can	O
solve	O
it	O
.	O
</s>
<s>
The	O
blocks	B-General_Concept
world	I-General_Concept
domain	O
is	O
an	O
example	O
for	O
a	O
toy	O
problem	O
.	O
</s>
<s>
Its	O
major	O
advantage	O
over	O
more	O
realistic	O
AI	B-Application
applications	O
is	O
,	O
that	O
many	O
algorithms	O
and	O
software	O
programs	O
are	O
available	O
which	O
can	O
handle	O
the	O
situation	O
.	O
</s>
<s>
In	O
its	O
basic	O
form	O
,	O
the	O
blocks	B-General_Concept
world	I-General_Concept
problem	O
consists	O
of	O
cubes	O
in	O
the	O
same	O
size	O
which	O
have	O
all	O
the	O
color	O
black	O
.	O
</s>
<s>
From	O
an	O
algorithm	O
perspective	O
,	O
blocks	B-General_Concept
world	I-General_Concept
is	O
an	O
np-hard	O
search	O
and	O
planning	O
problem	O
.	O
</s>
<s>
Automated	B-Application
planning	I-Application
and	I-Application
scheduling	I-Application
problem	O
are	O
usually	O
described	O
in	O
the	O
Planning	B-Application
Domain	I-Application
Definition	I-Application
Language	I-Application
(	O
PDDL	B-Application
)	O
notation	O
which	O
is	O
an	O
AI	B-Application
planning	I-Application
language	O
for	O
symbolic	O
manipulation	O
tasks	O
.	O
</s>
<s>
If	O
something	O
was	O
formulated	O
in	O
the	O
PDDL	B-Application
notation	O
,	O
it	O
is	O
called	O
a	O
domain	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
task	O
of	O
stapling	O
blocks	O
is	O
a	O
blocks	B-General_Concept
world	I-General_Concept
domain	O
which	O
stays	O
in	O
contrast	O
to	O
other	O
planning	O
problems	O
like	O
the	O
dock	O
worker	O
robot	O
domain	O
and	O
the	O
monkey	O
and	O
banana	O
problem	O
.	O
</s>
<s>
Decision	O
problem	O
(	O
Gupta	O
and	O
Nau	O
,	O
1992	O
)	O
:	O
Given	O
a	O
starting	O
Blocks	B-General_Concept
World	I-General_Concept
,	O
an	O
ending	O
Blocks	B-General_Concept
World	I-General_Concept
,	O
and	O
an	O
integer	O
L	O
>	O
0	O
,	O
is	O
there	O
a	O
way	O
to	O
move	O
the	O
blocks	O
to	O
change	O
the	O
starting	O
position	O
to	O
the	O
ending	O
position	O
with	O
L	O
or	O
less	O
steps	O
?	O
</s>
