From Rivest-Shamir-Wagner's paper[1]:
“Solving the puzzle should be like having a baby: two women can’t have a baby in 4.5 months."
[1] https://people.csail.mit.edu/rivest/pubs/RSW96.pdf
first thanks a lot for posting this to HN!
Then: is there a question somewhere in your post which I missed? : )
From Rivest-Shamir-Wagner's paper[1]:
“Solving the puzzle should be like having a baby: two women can’t have a baby in 4.5 months."
[1] https://people.csail.mit.edu/rivest/pubs/RSW96.pdf