S
OLUTION
:
An ultrametric tree, i.e., an edge-weighted tree
T(V,E)
with
n
leaves such
that, for any pair of leaves
i
and
j
,
where
denotes the sum of the weights in the path between
i
and
j
.
M
EASURE
:
The size of the tree, i.e.,
where
w(e)
denotes the
weight of edge
e
.
Bad News:
Not approximable within
for some
[
101
].