Warm Up – 3/25 - Tuesday Bill is taking a sales trip starting in Atlanta. Draw a graph that represents this table. Find the nearest neighbor tour from Atlanta.

Priority List Scheduling A priority list is a list of all the tasks prioritized in the order we prefer to execute them. If task X is ahead of task Y in the priority list, then if we are given the choice to do X or Y, we will perform task X. Priority lists are a time management device. The trick is finding a priority list that gives us a good time.

Example #1 Before launching a shuttle into space, five system checks (A, B, C, D, and E) must be performed. (Note: A(6) means it takes 6 hours to complete task A)

Priority List We are given the following priority list: A(6), B(5), C(7), D(2), E(5) We have two identical computers ( 𝑃 1 𝑎𝑛𝑑 𝑃 2 ) checking the systems. Our goal is to describe what happens!

Example #1 A(6), B(5), C(7), D(2), E(5) 𝑇=0 (𝑆𝑡𝑎𝑟𝑡). We assign 𝑃 1 to task A and 𝑃 2 to task B. 𝑇=5. 𝑃 1 is still working on task A. 𝑃 2 finishes task B. We cannot perform D until both A and B have finished! So we assign 𝑃 2 to begin work on C.

Example #1 A(6), B(5), C(7), D(2), E(5) 𝑇=6. 𝑃 1 has completed task A. 𝑃 2 is working on C. 𝐴 𝑎𝑛𝑑 𝐵 have both completed so we assign 𝑃 1 to D. 𝑇=8. 𝑃 1 finishes task D. There are no more tasks for 𝑃 1 so it sits idle. 𝑃 2 continues working on C.

Example #1 A(6), B(5), C(7), D(2), E(5) 𝑇=12. 𝑃 2 finishes task C. We assign 𝐸 to 𝑃 1 . 𝑇=17. 𝑃 1 finishes task E. We are ready for launch.

Example #2 Our previous priority list took quite a long time and was probably not an optimal use of time. Lets reverse our Priority list: E(5), D(2), C(7), B(5), A(6)

Example #2 E(5), D(2), C(7), B(5), A(6) 𝑇=0 𝑆𝑡𝑎𝑟𝑡 . We can start with A, B, or C. According to our priority list we start with B and C. 𝑃 1 gets assigned to C, 𝑃 2 gets assigned to B. 𝑇=5. 𝑃 2 finishes task B. 𝑃 1 still working on C. 𝑃 2 is assigned the only available task A.

Example #2 E(5), D(2), C(7), B(5), A(6) 𝑇=7. 𝑃 1 finishes task C. 𝑃 2 continues working on A. 𝑃 1 begins work on E which is the highest priority. 𝑇=11. 𝑃 2 finishes task A. 𝑃 2 begins working on 𝐷 2 . 𝑇=12. 𝑃 1 finishes E. Sits idle. 𝑇=13. 𝑃 2 finishes D. Finished.

Example #2 As you an see, there is much less idle time and the project gets done four hours faster!