[r-t] Bobs only Erin Triples (was: Composition search)

Andrew Johnson andrew_johnson at uk.ibm.com
Mon Nov 30 21:34:18 UTC 2015


> From: Don Morrison <dfm at ringing.org>
> On Sun, Nov 29, 2015 at 7:04 AM Richard Smith <richard at ex-parrot.com> 
wrote:
> > The group in question has all permutations of 123 while 456
> > permute in phase:
> > 
> >    123456  213546  231564  321654  312645  132465
> 
> Ah, thank you, I hadn't thought of permuting two chunks in phase 
> with one another.
> 
> > As always, Brian Price's 'Composition of Peals in Parts'
> > provides the definitive guide to these things.
> 
> And thanks for this reminder. I'd completely forgotten it contained 
> such a comprehensive catalog.
> 
> Next questions regarding the six part: if a true, bobs only 
> partition of the extent of Erin Triples into six chunks with those 
> part heads were possible, how do you join them together? Is it 
> guaranteed that there is a way? (Apologies if an answer to this is 
> also in Price's article--I've skimmed it again today, but not yet 
> put in the time and effort to fully digest it, but didn't see 
> anything that looked relevant.)
> 
It depends how the part-ends come out, as 6 1-parts, 3 2-parts or 
2 3-parts. If there were 3 2-part blocks and you were lucky then a 
Q-set of bobs or omits might link them together. It's not guaranteed,
compare with a 10-part of Stedman Triples were there is a division into
5 2-part blocks, but the available Q-sets do not link them together.

Andrew Johnson
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