Abstract
Let Q4 denote the graph, obtained from the rational points of the 4-space, by connecting two points iff their Euclidean distance is one. It has been known that its chromatic number is 4. We settle a problem of P. Johnson, showing that in every four-colouring of this graph, every colour class is every-where dense.
| Original language | English |
|---|---|
| Pages (from-to) | 259-266 |
| Number of pages | 8 |
| Journal | Aequationes Mathematicae |
| Volume | 37 |
| Issue number | 2-3 |
| DOIs | |
| State | Published - Jun 1989 |
Keywords
- AMS (1980) subject classification: Primary 05C15, Secondary 51K05, 52A37
ASJC Scopus subject areas
- General Mathematics
- Discrete Mathematics and Combinatorics
- Applied Mathematics