1. We have the following incomplete B&B tree:S7
Z=81.2 S3
Z=84.7 S1
Z=88.5 S8
Z=77
int S4
Z=75
int S9
Z=76.4
All
Z=93.2 S5
Z=80.3
S10
Z=79.1 S2
Z=82.4
S11
Z=75.8 S6
Z=78.5

2. What is the current incumbent? What is its value?
Give as tight as possible lower and upper bounds on the IP optimal value.
Which nodes are fathomed? Why?
Suppose before starting the branch-and-bound we have applied a fast heuristic to the problem. The heuristic has returned an integer solution with Z=80. How would this information change the solution tree?