http://snkhan.co.uk/forum/viewtopic.php ... ard#p28670
but this post concerns a more general challenge: folding the nxn checkerboard from a single square sheet of paper with one color per face. Additionnaly, the question is: what is the optimal design (i.e. the smallest initial square for the same folded design)?
An old (2000) upper bound on the paper size has been stated in
https://hal.archives-ouvertes.fr/hal-01380815
It has been outperformed (2009) in
https://dspace.mit.edu/openaccess-disse ... 21.1/62156
but only for n > 16. Since then, there have been several effectively folded models of the expected optimal chessboard (n=8), but I have not seen real models folded for a larger n.
So, here is my latest attempt: the 11x11 checkerboard
from a 60x60 paper (half-folded to feel the complexity).
The design principle is not new, and is described in
https://arxiv.org/abs/1510.07499
but the real physical folding may well be.
So, the question is:
the effective folding of the optimal 11x11 checkerboard (i.e. from the smallest initial square of paper - not proved but strongly suspected), is it a world record??