# Non trivial colouring of the edges of an infinite complete graph

Can you build a probabilistic scheme for colouring each edge (independently of all other edges) of the complete graph G on the positive integers such that the probability that G contains an infinite monochromatic complete subgraph is neither 0 nor 1?

• The question has been answered, but I'm still confused. Isn't Ramsey's theorem exactly the statement that there is always a infinite monochromatic complete subgraph, so that the probability would be identically 1? – Tom Church Oct 28 '09 at 5:28
• Well the infinite Ramsey theorem holds if you use only finitely many colours, but there is no such assumption here. Does that help? – Randomblue Oct 28 '09 at 10:29

## 1 Answer

It seems like this would go against the Kolmogorov 0-1 law.. If we let Xi denote the coloring of all of the edges from i to integers larger than i, wouldn't the existence of an infinite monochromatic subgraph be a tail event?

• I didn't know the definition of a tail event, nor did I know Kolmogorow's 0-1 law. But yeah, it's seems you are right... Disappointing. – Randomblue Oct 27 '09 at 18:28