Paper by Martin L. Demaine
- Erik D. Demaine, Martin L. Demaine, Yair N. Minsky, Joseph S. B. Mitchell, Ronald L. Rivest, and Mihai Pǎtraşcu, “Picture-Hanging Puzzles”, Theory of Computing Systems, volume 54, number 4, May 2014, pages 531–550.
We show how to hang a picture by wrapping rope around n nails,
making a polynomial number of twists, 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.
This construction makes for some fun mathematical magic performances.
More generally, we characterize the possible Boolean functions
characterizing when the picture falls in terms of which nails get removed
as all monotone Boolean functions. This construction requires an
exponential number of twists in the worst case, but exponential
complexity is almost always necessary for general functions.
- This paper is also available from SpringerLink, and as arXiv.org:1203.3602 of the Computing Research Repository (CoRR).
- Open Problem 1 was in fact previously solved by Gartside and Greenwood's paper "Brunnian links" (2007). The length of the shortest solution to the 1-out-of-n puzzle is Θ(n^2); in fact, the exact bound matches the 2002 Chris Lusby Taylor construction we present.
- The paper is 18 pages.
- The paper is available in PDF (6884k).
- See information on file formats.
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- Related papers:
- PictureHanging_FUN2012 (Picture-Hanging Puzzles)
See also other papers by Martin Demaine.
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Last updated November 20, 2018 by