<s>
The	O
many-body	B-Algorithm
problem	I-Algorithm
is	O
a	O
general	O
name	O
for	O
a	O
vast	O
category	O
of	O
physical	O
problems	O
pertaining	O
to	O
the	O
properties	O
of	O
microscopic	O
systems	O
made	O
of	O
many	O
interacting	O
particles	O
.	O
</s>
<s>
The	O
dimension	O
of	O
the	O
classical	O
many-body	B-Algorithm
system	I-Algorithm
scales	O
linearly	O
with	O
the	O
number	O
of	O
particles	O
.	O
</s>
<s>
In	O
quantum	O
mechanics	O
,	O
however	O
,	O
the	O
many-body-system	O
is	O
in	O
general	O
in	O
a	O
superposition	O
of	O
combinations	O
of	O
single	O
particle	O
states	O
-	O
all	O
the	O
different	O
combinations	O
have	O
to	O
be	O
accounted	O
for	O
.	O
</s>
<s>
Thus	O
,	O
many-body	B-Algorithm
theoretical	O
physics	O
most	O
often	O
relies	O
on	O
a	O
set	O
of	O
approximations	O
specific	O
to	O
the	O
problem	O
at	O
hand	O
,	O
and	O
ranks	O
among	O
the	O
most	O
computationally	B-Architecture
intensive	I-Architecture
fields	O
of	O
science	O
.	O
</s>
<s>
Many-body	B-Algorithm
problems	I-Algorithm
play	O
a	O
central	O
role	O
in	O
condensed	O
matter	O
physics	O
.	O
</s>
