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 88-89. The previous thread has passed 500 comments.
There is now 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.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically:
You do not need to rot13 anything about HP:MoR or the original Harry Potter series unless you are posting insider information from Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).
If there is evidence for X in MOR and/or canon then it’s fine to post about X without rot13, even if you also have heard privately from Eliezer that X is true. But you should not post that “Eliezer said X is true” unless you use rot13.
Given that a bunch of people in the Great Hall should know about the fact that one can send messages via patronus, it's a bit unlikely that no one of them thinks about sending a patronus to Minerva.
Harry is also quite stupid for sending the patroneus to Hermonine instead of addressing Dumbledore who could use the time turner (in Harry's perspective) and who also can go directly to Hermoine via Fawkes and is able to fight the troll. But then Harry thinks that he's the hero who has to do things himself, so that can be forgiven.
We could certainly expect Minerva to patronus directly after she left the Great Hall and tell Dumbledore and also other members of the order of the Pheonix. An attack on Hogwarth is certainly a big deal and I would suggest them to time turn as much people as possible to get them on the battlefield against the troll.
The only reason why the couldn't defend that way if there was some decoy event that already used up the time turner abilities of Dumbledore and Amelia Bones.
We also know that Hogwarts has alarms that trigger when a student get's hurt and getting your legs bitten up probably qualifies.
None of them know how to do it, though. (I assume you're talking about the various students who learned the Patronus spell.)