[r-t] What IS a rotation of a method?

[Matthew Frye]

On 18 Oct 2014, at 23:23, Simon Humphrey <sh53246 at gmail.com> wrote:

> Don Morrison:
>> Several people this morning have brought up different starts to Stedman as
>> examples of rotations. But no one has commented on the following. Is there
>> not some significant difference between simply starting in a different
>> place, and a more meaningful rotation of a method?
> 
> Yes. Grandsire is asymmetrical about the treble's path, and reversing its
> place notation with respect to the treble (which produces New Grandsire)
> does seem a more substantial alteration than rotating it, i.e. just starting
> the place notation at a different point.  This goes a long way towards
> justifying New Grandsire having its own name, to my mind.
> Stedman is symmetrical, and reversing its place notation produces the same
> principle, so there is no case for different starts to be given different
> names.
> 
> Looking at other examples of asymmetrical methods, reversing the place
> notation of Union Bob Minor produces Single Cambridge Cyclic Bob Minor.
> No-one seems to have objected to these methods being given different names.
> Why all the fuss about New Grandsire?

I think this probably goes to the heart of the disagreements over Grandsire/New Grandsire, namely that some people think of it as a rotation and some as a reversal. The Single Cambridge Cyclic Bob/Union Bob comparison is unambiguously a reversal.

New Grandsire is obviously a reversal of Grandsire, but I can see people would not necessarily think of it as a rotation as the treble has moved to a different line (albeit still plain hunting). Would people claim a different method again if it were rotated further so the 3 & 5 were the hunt bells? I doubt it, you'd just call it a rotation or a funny start(/funny calls) in Grandsire.

So. Perhaps we should clarify that, in most cases, we think that simply starting a method at a different point isn't enough to make a new method (e.g. Stedman, snap starts in treble dodging), but that reversing a method *is* enough to make a new method unless (countless examples, including SCCB/Union). The question is then what do we do when something is both a reversal and a rotation? (i.e. reversal of a symmetric method from a point that *isn't* the symmetry point, I think that's the only possible way to generate this situation)

(Hmmmmm, those arguments probably need to be tidied up a bit...)

Possible resolutions to this might be along the lines of:
- Prioritising the reversal convention, i.e. a reversal is allowed to be a different method, even if it's also a rotation.
- Prioritising the rotation convention, i.e. a rotation isn't allowed to be a different method, even if it's also a reversal.
- Differentiating between rotations that change a (primary?) hunt bell and those that don't.
- Making a special case in the rules for New Grandsire.

Other suggestions or opinions? I dislike the 3rd and 4th options, and I don't know how the 1st could avoid allowing reversals of normal palindromically symmetric methods.

MF