[r-t] in-course 120

Andrew Johnson andrew_johnson at uk.ibm.com
Wed Oct 4 09:36:10 UTC 2006

ringing-theory-bounces at bellringers.net wrote on 03/10/2006 20:40:01:

> Here is a little question I don't recall hearing about before:
> Find an IN-COURSE 120 of (pure) doubles, in which each in-course row 
> occurs once at hand and once at back.  (Any such can of course be 
> with a single to get a 240 with each row once at hand and once at back 
> only two single changes).
> I'm sure there are plenty of examples, but what about ones that can be 
> regarded as reasonably sensible methods?
> Ander
With a bit of experimentation I came up with

which has some nice symmetry.

Another way of using this method is to ring it to triples, e.g by 
the last change with '7' to give a principle of 168 changes, or replacing
the middle and last changes with '7' as required to make a touch.

Andrew Johnson

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