I agree that it needs to be unambiguous, but I don't feel that restating Bob And Sue as "What percentage of Bob's wins come in the second turn" is the duty of the questioner, even though that's an equivalent question AND it's a much simpler statement of the problem.
The problem as stated is unambiguous.
Re Monty Fall: No, in *that instance*, Monty's revelation still gives you additional information, and still results in there being a 2/3 chance of it being not behind your picked door. It's simply not usable as a basis for a universal strategy.
If Monty Fall opens the door *before* you pick, you're right, it's 50/50.
And yes, it's important to explain that the behaviour in the puzzle is universal: Monty will ALWAYS open a door and he will ALWAYS reveal a goat by doing so. Sue will ALWAYS roll first. Monty will never accidentally reveal the car, and he will never decide not to open a door, and if you've chosen correctly, which door he opens is random.
(no subject)
Date: 2011-08-18 02:33 pm (UTC)The problem as stated is unambiguous.
Re Monty Fall: No, in *that instance*, Monty's revelation still gives you additional information, and still results in there being a 2/3 chance of it being not behind your picked door. It's simply not usable as a basis for a universal strategy.
If Monty Fall opens the door *before* you pick, you're right, it's 50/50.
And yes, it's important to explain that the behaviour in the puzzle is universal: Monty will ALWAYS open a door and he will ALWAYS reveal a goat by doing so. Sue will ALWAYS roll first. Monty will never accidentally reveal the car, and he will never decide not to open a door, and if you've chosen correctly, which door he opens is random.