Timeline for Puzzle in 3D grid with black and white boxes, related to shelling

Current License: CC BY-SA 4.0

10 events

when toggle format	what		by	license	comment
Jul 29, 2018 at 18:45	history	edited	Sebastien Palcoux	CC BY-SA 4.0	Addition of two examples with (r,n) = (3,7), the second being a 90° rotation of the first.
Jul 29, 2018 at 10:43	history	edited	Sebastien Palcoux	CC BY-SA 4.0	Replaced the example by two example for (n,r) = (3,2) and (4,3), the second having an Eulerian ordering but not the first.
Jul 29, 2018 at 10:43	comment	added	Sebastien Palcoux		The example without Eulerian ordering (considered in the two above comments) was replaced by a 3 by 3 by 3 example. We also added a new 4 by 4 by 4 example having an Eulerian ordering.
Jun 3, 2018 at 12:38	history	edited	Sebastien Palcoux	CC BY-SA 4.0	error fixed in code (result invariant, except computation time doubled)
May 31, 2018 at 14:03	history	edited	Sebastien Palcoux	CC BY-SA 4.0	an example of partial Eulerian ordering of maximal length 11 + explanation why it cannot be completed.
May 31, 2018 at 3:48	history	edited	Sebastien Palcoux	CC BY-SA 4.0	distribution -> combination (more usual terminology)
May 30, 2018 at 21:42	history	edited	Sebastien Palcoux	CC BY-SA 4.0	sage code + brute-force search
May 30, 2018 at 21:10	comment	added	Sebastien Palcoux		@GerhardPaseman: Yes, for an ordering "Eulerian" is stronger than "collinear". The collinear condition is of the form "$\forall i>1, \exists j<i$...", whereas the Eulerian condition is of the form "$\forall i>1, \forall j<i, \exists k<i$...". For a 2D grid, these two conditions are the same, but it is no more true for a 3D grid (and beyond).
May 30, 2018 at 19:41	comment	added	Gerhard Paseman		This is different from collinear ordering, right? Because I see a (level by level) collinear ordering of your 4 by 4 by 4 example. Gerhard "Which Makes A Nice Puzzle" Paseman, 2018.05.30.
May 30, 2018 at 19:27	history	asked	Sebastien Palcoux	CC BY-SA 4.0