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21 votes
0 answers
453 views

Does every 5-celled animal tile the plane?

An animal in the plane is a finite set of grid-aligned unit squares in $\mathbb{R}^2$. (The definition is the same as a polyomino, but where we relax the connectivity requirement.) One may ...
RavenclawPrefect's user avatar
17 votes
1 answer
458 views

The sparsest planar net that captures every unit segment

Let $\cal C = \lbrace C_i \rbrace$ be a collection of rectifiable curves in the plane with the property that every unit-length segment meets at least one curve in at least one point. Call such a ...
Joseph O'Rourke's user avatar
15 votes
2 answers
737 views

Tiling survey that updates "Tilings and patterns"?

Can anyone suggest a survey (or surveys) that provides an update to Tilings and patterns by Grunbaum and Shepard? If there's a more recent book, that would be fantastic, but I don't see one. I am ...
Aaron Sterling's user avatar
11 votes
1 answer
406 views

Thinnest 2-fold coverings of the plane by congruent convex shapes

It is an unsolved problem to determine the "thinnest" $2$-fold covering of the plane by disks. The $2$-fold coverage problem by disks is to find the minimum number of congruent (unit-radius) disks ...
Joseph O'Rourke's user avatar
6 votes
2 answers
424 views

A class of tilings with amazing visual qualities

For more examples please see my related question on MSE: Interesting tiling with a lot of symmetrical shapes This is achieved by rotation of square grid over itself by atan(3/4). Resulting ...
Mikhail V's user avatar
  • 161
4 votes
2 answers
207 views

Classification of symmetries of tilings in surfaces?

Is there a general study of the symmetries of tilings on surfaces? Conway, Goodman-Strauss & Burgiel classified them on $\mathbb S^2, \mathbb R^2$ and $\mathbb H^2$, with their 'Magic Theorem'. ...
Melquíades Ochoa's user avatar
1 vote
2 answers
232 views

What does the extension theorem for tilings state?

I have seen several references to the so-called Extension Theorem in the context of tilings of Euclidean space. E.g. in "The Local Theorem for Monotypic Tilings" one reads The Extension Theorem [......
M. Winter's user avatar
  • 13.6k