[r-t] "X above, Y below"

[tuftyfrog at gmail.com]

> On 2 Aug 2017, at 00:34, Don Morrison <dfm at ringing.org> wrote:
> 
> On Tue, Aug 1, 2017 at 4:10 PM, Pip Dillistone <tuftyfrog at gmail.com> wrote:
> > With Bristol below and Double Dublin above you get a 2-3
> > differential with 2 and 3 both hunt bells:
> > 
> > https://complib.org/method/32289?accessKey=f8fac86bb06c104f84fdb9201f26a7ea0bef08c6
> 
> The Composition Library, via this link, says this method is asymmetric. Given the rule for generating it I'd naively thought it would have the usual, palindromic symmetry. What happens to break that? Presumably there must be some other, but still related and succinct, way to describe its reverse?
> 
> 
> 
> -- 
> Don Morrison <dfm at ringing.org>
> "Great theories don't simply appear in someone's head as if by magic,
> but take time to blossom. The so-called 'eureka' cry is more an
> exclamation of mental relief than a cry of sudden revelation."
>           -- Marcello Gleiser, _The Dancing Universe_
> 
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Sorry, this is my mistake in transcribing the method ― as far as I can tell it should indeed be palindromic. 

I chose to define "over" to mean "the 2nd is over the treble in this particular row". Since the path of the 2nd is determined by the rule from the outset, this made the most sense to me at the time. It's remarkably fiddly to work out what to do when the 2nd is dodging with the treble, and it's here that I've made the mistake ― just after the halfway point there should be a 34 instead of a 14 in the notation, for example. 

Pip
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