Australia must have thought about it, given they just need a point to qualify for the knockouts today.

I suspect that, like for 5 teams 1 pitch, other than swapping the numbers (eg all 8s for all 2s) or reversing the order, it's the only solution. Can that be proved? Are there any similar interesting questions we can ask?

Here's a solution:
21 43, 56 78,
91 23, 54 76,
31 98, 52 74,
39 68, 51 72,
96 48, 53 71,
46 28, 59 73,
26 18, 49 75,
16 38, 42 79,
36 58, 41 29.

Note several teams have double rest, then 5 then 7, double rest, then 8 then 6.

I've been using this as my test for ChatGPT versions, and earlier versions were confidently wrong. But first go at ChatGPT5 and it has found an example! Interestingly, when I ask it again, it can't do it - it just gets stuck. But I'm less sceptical of ChatGPT/AI than I was yesterday.

What if you have the same problem with 2 pitches? 8 teams is impossible as for similar reasons to my first tweet you get stuck fairly quickly. 10 is OK. How about 9? I spent so long trying to find an example that worked for 9 that I suspected it must be impossible, but I couldn't prove that either.

I learned about this because at the (men's) rugby world cup they have pools of five teams, and smaller countries were having to play the 5 role, playing in games 3, 5, 7 and 9 whilst another country got more rest by playing games 1, 4, 7 and 10. But they could at least get 1 game rest.

For five the solution is:
1v2, 3v4, 5v1, 2v3, 4v5, 1v3, 5v2, 4v1, 3v5, 2v4.

It's unique, but you could swap the numbers (eg all 1s for all 3s) or reverse the order.

What about
12, 34, 51, 23, 45, 13, 24, 35, 41, 52?
It is just the same as the first, reversed with some numbers swapped. (Try it!)

I think most British people feel the same. I always thought of them as a weird US thing and have never personally seen one here (but then I'm not a concert goer).

I use the app of the train company I'm travelling on, because it makes claiming delay repay more convenient if it's needed.

Yes, I have 9 rail franchise apps on my phone.

Enjoy it, our brief time. Soon enough it’ll be back to nine months of grey and the other team will be posting ‘thank the Lord, all semblance of cheer has vanished from the air again’.

Thanks - that makes sense.

I'd genuinely love to know if you think Twenty20 is as good and if not, why?