[r-t] New method - Auryn Differential Minor

[Alexander Holroyd]

We just rang an extent of an interesting new minor method, devised by 
Tristan Parker of Seattle.  It is a (2,4)-differential, with the plain 
course being the group of all rows that can be obtained from the 
mirror-symmetric place notations -,34,25,16.  The latter property is 
shared by the principle Kidderminster, and the fact that the plain course 
is a group means that extents are readily obtained.

http://www.boojum.org.uk/cgi-bin/line.pl?bells=6&pn=-34-1-25-1.34-34.1&title=Auryn%20Differential%20Minor&lines=1&line=2&line1=b&line1c=red&line1w=1%2F2pt&line2=b&line2b=2&action.x=1

What makes Auryn different is that the "hunt bells" 1 and 6 ring 
treble-bob hunt.  It turns out an extent is possible using only 4ths place 
bobs without affecting the treble, so the treble simply treble-bobs 
throughout.  It's essentially unique, and very elegant.  The method is fun 
to ring: interesting but not too difficult.

720
2 4 23456
---------
3 - 23564
- 2 42356
---------
3 part

Curiously, this extent can be re-interpreted as the "standard calling" of 
the 5-lead treble-bob method whose lead is two leads of Auryn called p-, 
with an omit as the call:

-34-1-25-1.34-34.1-34-1-25-1.34-34.4 le 154263
bob=16

720
I O 2345
---
- - 5432
   - 4235
---
3 part
(bob whenever 6 unaffected unless 5 also unaffected)

A priori there is no reason to expect that the standard calling would work 
for this method - it is asymmetric, and it has the section -25-, which 
disrupts the usual nature of the rows.  In particular, I don't believe 
there is a set of 6 mutually true courses, and the partial courses rung 
between the I and O do not complement each other to form complete courses 
(as they do in the standard calling of standard TD methods).

I'd like to understand better how this works (of course there is no 
difficulty if one interprets it as the original differential method).

Are there other examples of TD methods for which the standard calling 
works but that do not admit 6 mutually true courses?

Ander