paradox · traps · decisions
Sleeping Beauty paradox
Half, or one third? Both answers are still in the room.
She wakes and asks the chance of heads. Which count answers her?
Monday
Heads
Monday
Tuesday
Tails
Heads wakes her once, on Monday. Tails wakes her on Monday and on Tuesday.
The coin is heads
Lock an answer, then flip the week.
—This week
—Heads among weeks
—Heads among awakenings
The coin is fair, so half the weeks are heads.
Tails wakes her on Monday and again on Tuesday. Heads wakes her once.
Heads is about half of the weeks and about one third of the awakenings. The scoring rule picks which of those two numbers answers the question.