<s>
Tree	B-Algorithm
rearrangements	I-Algorithm
are	O
deterministic	B-General_Concept
algorithms	I-General_Concept
devoted	O
to	O
searching	O
for	O
an	O
optimal	O
tree	B-Data_Structure
structure	I-Data_Structure
.	O
</s>
<s>
The	O
simplest	O
tree-rearrangement	O
,	O
known	O
as	O
nearest-neighbor	B-Algorithm
interchange	I-Algorithm
,	O
exchanges	O
the	O
connectivity	O
of	O
four	O
subtrees	O
within	O
the	O
main	O
tree	O
.	O
</s>
<s>
Finally	O
,	O
tree	B-Algorithm
bisection	I-Algorithm
and	I-Algorithm
reconnection	I-Algorithm
(	O
TBR	O
)	O
detaches	O
a	O
subtree	O
from	O
the	O
main	O
tree	O
at	O
an	O
interior	O
node	O
and	O
then	O
attempts	O
all	O
possible	O
connections	O
between	O
edges	O
of	O
the	O
two	O
trees	O
thus	O
created	O
.	O
</s>
<s>
The	O
increasing	O
complexity	O
of	O
the	O
tree	B-Algorithm
rearrangement	I-Algorithm
technique	O
correlates	O
with	O
increasing	O
computational	O
time	O
required	O
for	O
the	O
search	O
,	O
although	O
not	O
necessarily	O
with	O
their	O
performance	O
.	O
</s>
<s>
Variants	O
of	O
the	O
method	O
use	O
standard	O
genetic	B-Algorithm
algorithms	I-Algorithm
with	O
a	O
defined	O
objective	O
function	O
to	O
swap	O
high-scoring	O
subtrees	O
into	O
main	O
trees	O
that	O
are	O
high-scoring	O
overall	O
.	O
</s>
