Where do 13 sides come from? Is it related to a number of transformations?
Where do 13 sides come from? Is it related to a number of transformations?
Anyway, I agree that people like to focus on the elegant parts. Math popularization materials have too much kawaii math.
It has been proven using a computer. The problem was first reduced to a few hundred cases, then a brute force algorithm was used to solve each case.
So we know the minimum number of sides is at least five.
Assuming 13 sides is established as the minimum, I suspect there is no 'nice' reason for it; its just that this may be the minimum number to give you sufficient degrees of freedom.
The monster: https://youtu.be/mH0oCDa74tE
Ideal packing of squares (some are elegant, 17 is not) https://kingbird.myphotos.cc/packing/squares_in_squares.html
The 4 color theorem was solved by reducing it down to 633 cases and just using a computer to find a coloring for each case: https://en.m.wikipedia.org/wiki/Four_color_theorem