9. Whew! Now that the spacecraft has been repaired (after the asteroid strike) and the partition...

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9. Whew! Now that the spacecraft has been repaired (after the asteroid strike) and the partition has healed, you realize you're almost at Saturn! You're no longer seeing your dog Einstein and cat Doraemon (though you kinda hear them sometimes, which makes you question your own sanity). You notice that there are fewer astronauts up in the command center of the spacecraft-you say to yourself they're all probably resting up for the landing. Anyway, to make sure nothing goes wrong during landing, it's time to make sure the virtual synchrony implementation in the datacenter is correct. You and Commander Amelia Brand sit down together and see the following instances in the log. For each of the following executions, say whether it is a) correct (and why), or b) if it is incorrect (and what change in the timeline would have made it correct). a. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32, however then p3 fails, and p1 and p2 have deliver the next view V12={p1,p2), and only then do p1 and p2 deliver M32. b. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32, however it is not delivered at p1, p2 or p3. Then p3 fails and p1 and p2 deliver the next view V12={p1,p2}. c. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32, and p1 delivers it immediately. However then p3 fails and p1 and p2 deliver the next view V12={p1,p2). Only then does p2 deliver M32. d. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32 and concurrently p2 multicasts message M45. Both p1 and p2 deliver each others' messages, but they never deliver their own multicasts. But p3 6 fails and never receives either message. Then p1 and p2 deliver the next view V12={p1,p2}. e. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32 and concurrently p2 multicasts message M45. p1, p2, and p3 all deliver M32 and M45 each. Then p1 and p2 deliver the next view V12={p1,p2}; when p3 receives this view, it delivers the view V12. f. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32, and delivers it immediately, and then p1 fails. p2 and p3 each respectively deliver the views {p2} and {p3}. M32 is never delivered at p2 or p3. g. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32. A fourth process p4 joins, and all processes p1-p4 deliver the next view V12={p1,p2,p3,p4}. M32 is delivered then at processes p1-p4. 9. Whew! Now that the spacecraft has been repaired (after the asteroid strike) and the partition has healed, you realize you're almost at Saturn! You're no longer seeing your dog Einstein and cat Doraemon (though you kinda hear them sometimes, which makes you question your own sanity). You notice that there are fewer astronauts up in the command center of the spacecraft-you say to yourself they're all probably resting up for the landing. Anyway, to make sure nothing goes wrong during landing, it's time to make sure the virtual synchrony implementation in the datacenter is correct. You and Commander Amelia Brand sit down together and see the following instances in the log. For each of the following executions, say whether it is a) correct (and why), or b) if it is incorrect (and what change in the timeline would have made it correct). a. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32, however then p3 fails, and p1 and p2 have deliver the next view V12={p1,p2), and only then do p1 and p2 deliver M32. b. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32, however it is not delivered at p1, p2 or p3. Then p3 fails and p1 and p2 deliver the next view V12={p1,p2}. c. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32, and p1 delivers it immediately. However then p3 fails and p1 and p2 deliver the next view V12={p1,p2). Only then does p2 deliver M32. d. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32 and concurrently p2 multicasts message M45. Both p1 and p2 deliver each others' messages, but they never deliver their own multicasts. But p3 6 fails and never receives either message. Then p1 and p2 deliver the next view V12={p1,p2}. e. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32 and concurrently p2 multicasts message M45. p1, p2, and p3 all deliver M32 and M45 each. Then p1 and p2 deliver the next view V12={p1,p2}; when p3 receives this view, it delivers the view V12. f. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32, and delivers it immediately, and then p1 fails. p2 and p3 each respectively deliver the views {p2} and {p3}. M32 is never delivered at p2 or p3. g. p1, p2, p3 each deliver a view V11={p1,p2,p3}. Then p1 multicasts message M32. A fourth process p4 joins, and all processes p1-p4 deliver the next view V12={p1,p2,p3,p4}. M32 is delivered then at processes p1-p4.