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A comment on Seven Puzzles You Think You Must Not Have Heard Correctly (2006) [pdf]. Parent comment

Re:Seven Puzzles You Think You Must Not Have Heard Correctly... by rntz on Monday August 29, 2016 @09:49AM (#12381798)
Couldn't I start in a "tail" leading to a cycle that doesn't include my name? Suppose my name is "A", and I proceed:

check box A - read name B; check box B - read name C; check box C - read name B

and now I'm in a B-C loop, and will never find my name.

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Re:Seven Puzzles You Think You Must Not Have Heard Correctly... by agf on Monday August 29, 2016 @09:51AM (#12381806)
Re-read your scenario -- you have both box A and box C containing name B, but the problem statement says each name appears only once. So you can't get into cycles like this.
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Re:Seven Puzzles You Think You Must Not Have Heard Correctly... by rntz on Monday August 29, 2016 @09:52AM (#12381822)
Ah, of course! That guarantees there are no "tails"; every name (& box) is part of exactly one cycle. And this is then a property of cycles of permutations generally. Thanks!
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Re:Seven Puzzles You Think You Must Not Have Heard Correctly... by hundt on Monday August 29, 2016 @09:51AM (#12381812)
No, because in your example both boxes A and C have name B in them. That's against the rules.
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Re:Seven Puzzles You Think You Must Not Have Heard Correctly... by twoodfin on Monday August 29, 2016 @09:52AM (#12381819)
No, then "B" would be in two boxes: A and C.
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