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 |
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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