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@OscarCunningham@mathstodon.xyz

2026-08-01 06:10 UTC

Can you colour the faces of a dodecahedron black and white so that if you stand on one of the faces you can determine your position and orientation by looking at your face and the adjacent faces? #math #maths #mathematics

Replies (4)

  • @ianh@mastodon.social 2026-08-01 07:30

    @OscarCunningham@mathstodon.xyz i wrote a program that enumerates all the colorings, and it doesn't find any that work: http://ianhenderson.org/2026-08-01-dodecahedron.c.txt (the face numberings were from putting labels on a real-life icosahedron i had handy, so i could have made mistakes during that process, but the group it generates does have order 60 at least)

    Open ##4327327

  • @vnikolov@ieji.de 2026-08-01 07:57

    For each face, I suppose. (I guess not.) It might be an interesting problem to find the maximum number of faces for which this can be achieved, since it's trivially possible for a single face (if I am not mistaken working it out in my head). @OscarCunningham@mathstodon.xyz

    Open ##5135851

  • @jmopp@masto.ai 2026-08-01 08:26

    @OscarCunningham@mathstodon.xyz First thought is that it's equivalent to finding a colouring of the dodecahedral graph such that every 6-tuple of a node and its neighbours has a unique colouring up to rotation. There are at most 4096 2-colourings of a graph with 12 nodes, so it's very brute-forceable. And I see someone beat me to it.

    Open ##5135852

  • @ngons@mathstodon.xyz 2026-08-01 09:15

    @OscarCunningham@mathstodon.xyz but if it doesn’t work, what is the minimum amount of colours?

    Open ##5135853