Consider the following special type of shortest-path problem
(see Sec. 9.3) where the nodes are in columns and the only
paths considered always move forward one column at a time.
in each column indicate the order of the deliveries), along with the
estimated time required to traverse the route.
Dispatcher is an interactive system that shows these routes to
Sharon for her approval or modification. (For example, the computer
may not know that flooding has made a particular route infeasible.)
After Sharon approves these routes as attractive possibilities
with reasonable time estimates, Dispatcher next formulates
and solves a BIP model for selecting three routes that minimize
their total time while including each delivery location on exactly
one route. This morning, Sharon does approve all the routes.
(a) Formulate this BIP model.
C (b) Use the computer to solve this model.