Vision-obstructing tiles

One of the obsessions of my teen years.

When I was in my mid to late teens I spent a lot of time working on various geometric problems for no obvious reason. As I’ve grown and learned how to think more rigorously, some of these come back to mind and I think “How quaint;” others still intrigue me.

One that I still find interesting is the following tile:

This tile has the property that every straight line drawn over the tiling touches a black portion of a tile at least once in 2.5 tile lengths. Or, as I put it in my youth, “If the filled-in squares are pillars your vision is obstructed in every direction no matter where you stand.”

I spent many hours in my youth trying to find other “open” tilings with this same property. I hoped to find one that filled in less than

2 |

9 |

With academic maturity, I can pose what I was hoping for more crisply.
“Given a tiling of black-and-white tiles,
let `b` be the maximum distance
between two points in the tile contiguously connected by black
and `w` be the minimum distance between two black points
that are not contiguously connected.
For what ratios `r` =

w |

b |

There are other interesting questions here too.
for example, I proved the absence of an all-white line
via exhaustive analysis of all angles.
Is there a cleaner way to prove it mathematically?
What would a proof that `r` is the maximum ratio above which no such tiles exist look like?
Are there tiles with this property for every `r`?
For a given `r`, how small can the longest white line segment be forced to become?
How small can the tile be?

I have no real reason to care about this problem. There is no obvious application, outside of maybe a strange game environment. And yet it continues to interest me, in a passive sort of way, and that one tiling that I have found has brought me a smile each time I see it for more than half my life.

Loading user comment form…

Looking for comments…