I
NSTANCE
:
Graph
, weight
and length
for each
, positive integer
B
.
S
OLUTION
:
A spanning subgraph
for
G
such that the sum of the weights
of the edges in
E'
does not exceed
B
.
M
EASURE
:
The diameter of the spanning subgraph.
Bad News:
Not approximable within 2
for any
[
296
].
Comment:
Not approximable within 3/2
for planar graphs.
Not approximable within 5/4
if
l(e)=1
for every edge
e
[
296
].
For results on minimum Steiner trees of bounded diameter, see M
INIMUM
S
TEINER
T
REE
.