Stackexchange iconStackexchangeSep 9, 2026 ~1 min source read

Tiling torus with hooks

We saw in a beautiful recent question by @Bubbler how to tile some rectangles with copies (including rotations and flips) of a hook, i.e., the four-celled polyplet shown below. Sadly, some rectangles can't be tiled with hooks: these are the 8k × 3 and 8k × 5 grids for any positive integer k.

Tiling torus with hooks

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We saw in a beautiful recent question by @Bubbler how to tile some rectangles with copies (including rotations and flips) of a hook, i.e., the four-celled polyplet shown below.

Sadly, some rectangles can't be tiled with hooks: these are the 8k × 3 and 8k × 5 grids for any positive integer k.

That made me wonder if these grids could be tiled when they were tori instead of rectangles.

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The useful part

We saw in a beautiful recent question by @Bubbler how to tile some rectangles with copies (including rotations and flips) of a hook, i.e., the four-celled polyplet shown below. Sadly, some rectangles can't be tiled with hooks: these are the 8k × 3 and 8k × 5 grids for any positive integer k. That made me wonder if these grids could be tiled when they were tori instead of rectangles.

How it works

  • That is, if the opposite edges of the rectangle are identified, can you tile the 8 × 3 and 8 × 5 grids with hooks?
  • In fact, on such torus grids with an odd dimension, the checkerboard argument in the linked answer fails (thanks to @Bubbler for pointing out), so there don't have to be equal number of the two parities of...

Details worth keeping

So one might wonder if grids of the form 4 × odd can be tiled.

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