3 ms·

The title implies that removing at most k nails makes it fall, the actual paper deals requires at least k nails to be removed to make it fall.

• willvarfar 15y ago
  "such that the picture falls whenever any k out of the n nails get removed, and the picture remains hanging when fewer than k nails get removed." I interpret that to mean exactly K nails; no more, no less.
  • kiiski 15y ago
    If it falls when exactly K nails are removed, I don't think it will go back up when you remove the K+1th nail. And if you remove k-1 nails first, and then remove 2 more simultaneously, the picture will fall anyway. So it's ">= K".
    • spicyj 15y ago
      "At least k" might imply that removing more than k nails is necessary to make the picture fall, which is not the case. I think "exactly k" is perfectly clear.
      • aplusbi 15y ago
        "Exactly k" is not clear because the picture will still fall if you remove k+1 nails. I think it's harder to get clearer than the way it's stated in the paper: "the picture falls whenever any k out of the n nails get removed, and the picture remains hanging when fewer than k nails get removed."