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Mar 15, 2020 at 13:54 comment added Nandakumar R The construction given on mathoverflow.net/questions/145314/… probably works for zero density arrangements with half-disks (semidisks) too - this appears to follow from all boundaries between a region with disks and the empty region being concave polylines as noted there.
Mar 14, 2020 at 17:37 comment added Nandakumar R And Wojowu, I too would like an answer to the question you raised. Thanks
Mar 14, 2020 at 17:31 comment added Nandakumar R Thanks TonyK. the link you gave shows the construction given in mathworld.wolfram.com/RigidCirclePacking.html is not quite optimal (zero density) - The construction drawn by Prof. O'Rourke does not look a straight enhancement of the picture given in the above Mathworld page. And yes, after some experimentation, I am unable to see how the kind of construction beginning with a hexagonal lattice of disks can be naturally done with unit squares.
Mar 13, 2020 at 20:50 comment added Yoav Kallus For unit squares I believe you should be able to use the structure in the mathworld illustration, replacing the circles with alternating coordinate-aligned squares and 45-degree-rotated squares so that each square of one orientation is wedged between three squares of the other orientation.
Mar 13, 2020 at 20:06 comment added Wojowu The question now is: is there a shape which does not admit density zero rigid packings?
Mar 13, 2020 at 19:50 comment added Nandakumar R thanks... made a corrective edit.
Mar 13, 2020 at 19:49 history edited Nandakumar R CC BY-SA 4.0
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Mar 13, 2020 at 18:54 comment added Yoav Kallus Why do you write "probably" the thinnest? The packing by Böröczky cited on that page and in the linked question has density zero. Are you suggesting there may be ones with negative density?
Mar 13, 2020 at 18:52 comment added TonyK See this question and answers for packings with zero density.
Mar 13, 2020 at 18:22 history edited Nandakumar R CC BY-SA 4.0
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Mar 13, 2020 at 18:21 history edited YCor CC BY-SA 4.0
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Mar 13, 2020 at 18:20 history asked Nandakumar R CC BY-SA 4.0