In an alternate universe, Peter and Sarah could have had the following conversation instead:
P: I don't know the numbers.
S: I knew you didn't know the numbers.
P: I knew that you knew that I didn't know the numbers.
S: I still don't know the numbers.
P: Now I know the numbers.
S: Now I also know the numbers.
But I'm worried that my version of the puzzle can no longer be solved without brute force.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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4. Open Threads should start on Monday, and end on Sunday.