I would like to know the minimum number k such that the plane R^2 can be coloured with k colors such that no colour contain all the possible distances. In other words, a colouring such that each color forbids a distance (not necessarily the same as it is the case for <http://en.wikipedia.org/wiki/Hadwiger%E2%80%93Nelson_problem>)


Has this problem been studied? It is easy to prove that 2 colors isn't enough, but I don't know for 3 colors...
We also know that this number k is at most 7 (using <http://en.wikipedia.org/wiki/File:Hadwiger-Nelson.svg> for example), but I did not find any better bound yet.


Bests,



Coloring of the plane
Seems to be the **polychromatic number of the plane**.


According to my knowledge, the value is at least 4 (due to Raiskii) and at most 6 (due to Stechkin).


See Chap. 4 and 6 of *The Mathematical Coloring book*.


