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

Richard Smith richard at ex-parrot.com
Tue Dec 1 11:24:08 UTC 2015

Alexander Holroyd wrote:

>> But I'm a bit confused by your assertion that none of 
>> these searches even produced a set of mutually true 
>> blocks.  There are a bunch of sets of mutually true 
>> blocks for various part end groups.  For example, 
>> composition number 5 (by PABS) in PABS's Collection [...]
> Richard, can you clarify this point, please?

No, at the moment I can't.  You do seem to have a valid 
point, at least with regard to PABS' 10-part, which is the 
one I've started looking at in detail.  But I need to spend 
more time to see where the discrepancy is.

My code looks for a single round block of 84 sixes (for the 
10-part), and if PABS' 10-part works with two or more round 
blocks covering the 10-part extent then it won't have turned 
up in my search.  My initial thought had been that this was 
a harmless omission: that it would result in me missing 
certain sets of blocks that could only be joined by singles, 
but not anything that could be joined with bobs because, I 
had thought, if it were possible to join with bobs, the 
joined version would also turn up in my search.  But I think 
I'm wrong; or at least, not sure I'm right.


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