[r-t] Adjacency in Extension

[Mark Davies]

Phil Barnes writes,

 > Nearly everyone on this list knows this. So my question
 > is why do we persist and go even further with the same
 > paradigm rather than finding another way?
I think the paradigm is pretty good, actually. There are lots of good 
extensions. The Bristol family, from Major upwards, is a beautiful 
example of a simple rule generating what is essentially the same method 
at any infinite number of stages. But it tells us:

1. Series can sensibly start at zero (for Bristol, the number of wrong 
dodges). I think Andrew is wrong to discount this.

2. We ought to consider root extensions where there isn't room to fit 
something into the row.

3. The existing extension mechanism, based on section-by-section 
expansion, isn't general enough (Bristol expands in the middle of a 
section).

I think the current extension rules are pretty good, with the exception 
that they have some fairly arbitrary restrictions built in (adjacency, 
the primacy of the section) which could be usefully relaxed.

MBD