[r-t] Extents of minor

[Stephen Penney]

MB: "There must really be loads - as well as all the extents using sensible
methods, there will be vastly many more which have no structure, but are
just seemingly random sequences of changes."

It would be an interesting challenge to ring one of these. Even better,
produce seven completely random extents and ring a peal. Even better than
that - find a completely random extent of triples!

I tried to break this problem down a bit, so started by counting the extents
of singles (there are two, rather obviously). Then I wrote out all the
changes of minimus in a big circle and started drawing lines between them
representing valid changes. Then I got bored when I realised just how many
routes there were going to be, and that the majority of these wont be
extents.

Percy