- INSTANCE:
Rooted tree
,
a forward travel time
,
a backward travel time
,
a release time
,
and an handling time
.
- SOLUTION:
A vehicle routing schedule that starts from ,
visits all nodes of
*T*, returns to , and, for any node , starts processing not before the release time , i.e., a permutation of and a waiting function*w*such that, for any*i*,

where*d(u,v)*denotes the length of the unique path from*u*to*v*. - MEASURE:
The total completion time, i.e.,

*Good News:*Approximable within 2 [298].