with unique labels on the leaves
and with edge weights
. A 3-degree tree
T'
with the
same set of unique labels as
T
.
representing nearest neighbour
interchanges transforming the tree
T
into
T'
(so that the labels match).
A nearest neighbour interchange of
is a transformation where
one of the two subtrees adjacent to
u
is exchanged with one of the two
subtrees adjacent to
v
.
.
where
n
is the number of leaves
[
91
].
Viggo Kann