Pessimistic assumption: There are more than two endings. A solution meeting the stated criteria is a necessary but not sufficient condition for the least sad ending.
If a viable solution is posted [...] the story will continue to Ch. 121.
Otherwise you will get a shorter and sadder ending.
Note that the referent of "Ch. 121" is not necessarily fixed in advance.
Counterargument: "I expect that the collective effect of 'everyone with more urgent life issues stays out of the effort' shifts the probabilities very little" suggests that reasonable prior odds of getting each ending are all close to 0 or 1, so any possible hidden difficulty thresholds are either very high or very low.
Counterargument: The challenge in Three Worlds Collide only had two endings.
Counterargument: A third ending would have taken additional writing effort, to no immediately obvious didactic purpose.
A necessary condition for a third ending might involve a solution that purposefully violates the criteria in some respect.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 113.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
IMPORTANT -- From the end of chapter 113: