Skip to main content

Timeline for Covering a Cube with a Square

Current License: CC BY-SA 3.0

20 events
when toggle format what by license comment
Mar 29, 2017 at 17:22 comment added Gerhard Paseman Also, if you are clever about folding and stacking, this involves only two straightedge cuts and one fold, whereas the dissection above needs at least two folds to reduce the number of straightedge cuts to two. Gerhard "Time Is Money Is Product" Paseman, 2017.03.29.
Mar 29, 2017 at 17:14 comment added Gerhard Paseman As I discovered after posting mathoverflow.net/a/263267, one can cut down the vertical middle of the 2x3 rectangle (forming two 1x3's) for another 5 piece cover, with pieces whose shapes are easier to manage in practice, with the same small triangle piece as being the smallest bit of paper to handle. Gerhard "Thinking In Mass Production Terms" Paseman, 2017.03.29.
Mar 29, 2017 at 11:38 history edited Joseph O'Rourke CC BY-SA 3.0
Image links broken; now fixed.
Feb 26, 2015 at 1:55 history edited Yoav Kallus CC BY-SA 3.0
updated urls for some pictures
May 6, 2012 at 20:11 vote accept Joseph O'Rourke
Apr 1, 2017 at 11:52
May 4, 2012 at 16:07 comment added Gerhard Paseman Hmm. Maybe the above L shaped suggestion involves 6 pieces. Gerhard "Let Me Count Them Again" Paseman, 2012.05.04
May 4, 2012 at 16:05 comment added Gerhard Paseman If I haven't messed up, another five piece construction starts with cutting a 2 by sqrt(6) rectangle from the square, cutting an L shape out of the corner, and use the remaining pieces to form another L shape. This covers four faces of the cube with the cut lines being on cube edges and not on the faces. Gerhard "Pretty Is In Beholder's Eye" Paseman, 2012.05.04
May 4, 2012 at 12:19 history edited Joseph O'Rourke CC BY-SA 3.0
Added photos.
May 4, 2012 at 10:18 comment added Joseph O'Rourke Wow! $\mbox{}$
May 4, 2012 at 4:21 comment added Yoav Kallus OK. Posted to soon earlier. The change from the T tetromino to the S tetromino actually allows going down to five pieces instead of six.
May 4, 2012 at 4:19 history edited Yoav Kallus CC BY-SA 3.0
added 13 characters in body
May 4, 2012 at 3:56 comment added Yoav Kallus Changed answer to CW.
May 4, 2012 at 3:54 history made wiki Post Made Community Wiki by Yoav Kallus
May 4, 2012 at 3:48 comment added Yoav Kallus Fedja, that's a great improvement on my extremely lazy effort! I like your construction, but I made an illustration of a slightly more symmetrical version of it, which I find a little more pleasing.
May 4, 2012 at 3:44 history edited Yoav Kallus CC BY-SA 3.0
added 556 characters in body
May 4, 2012 at 0:34 comment added fedja Assuming that "pieces" mean "connected polygonal pieces", we can take a 3 by 2 rectangle, cut it into a T-shape and two unit squares and then use the standard "sliding cut" to turn it into a square, giving the total of 6 pieces to cover the unit cube. Can we do better?
May 4, 2012 at 0:15 comment added fedja Actually, any two polygons of the same area are equidecomposable and the surface of the cube can be unfolded into a polygon, so the result is nice but not terribly surprising. Of course, the question about the minimal number of pieces remains.
May 3, 2012 at 23:54 history edited Joseph O'Rourke CC BY-SA 3.0
added 282 characters in body; added 1 characters in body
May 3, 2012 at 23:51 comment added Joseph O'Rourke Brilliant!! :-)
May 3, 2012 at 21:10 history answered Yoav Kallus CC BY-SA 3.0