Published online by Cambridge University Press: 19 October 2020
We study and classify proper q-colourings of the ℤd lattice, identifying three regimes where different combinatorial behaviour holds. (1) When $q\le d+1$, there exist frozen colourings, that is, proper q-colourings of ℤd which cannot be modified on any finite subset. (2) We prove a strong list-colouring property which implies that, when
$q\ge d+2$, any proper q-colouring of the boundary of a box of side length
$n \ge d+2$ can be extended to a proper q-colouring of the entire box. (3) When
$q\geq 2d+1$, the latter holds for any
$n \ge 1$. Consequently, we classify the space of proper q-colourings of the ℤd lattice by their mixing properties.