[r-t] Similar compositions

Andrew Johnson andrew_johnson at uk.ibm.com
Wed Jan 24 01:59:07 UTC 2018

> One suggestion is to hash the generated rows (or the place notation
> for them). However in practice this is not that helpful. Firstly if
> the order of the rows is not taken into account, compositions for
> extents would generate the same hash. Secondly, hashes for the same
> composition applied to a different method would not match, nor would
> rotations or reversals using the same method.
> Graham
I can see a couple of cases where the hashing the rows ignoring order 
could be useful. A lot of 6-part quarter peals of Grandsire Triples have 
two places in each part where a bob can be replaced with a single or vice 
versa half-way and at the end. Look for the 3 bells that rotate in each 
part and choose a place where 2 of the 3 are at the front. Perhaps that is 
different enough from a rotation or reversal to be counted as an 
arrangement but it doesn't seem like an original composition.

Also some compositions can have a Q-set of bobs added/removed which just 
shuffles the pieces around. Alan Burbidge calls these 'neutral Q-sets' in 
'Stedman Triples and Similar Fascinations'.

Andrew Johnson

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