[r-t] Delta-based transposition representation

Mark Davies mark at snowtiger.net
Wed Jun 15 08:01:21 UTC 2016

Basil Potts writes,

> Is it possible to occasionally provide a
> non-technical summary of, say, what has been achieved so far by the experts?

I guess that what has been described in this thread is really to do with 
the fundamentals of processing change-ringing in a computer. There are 
various ways of representing a row and a change, and various methods of 
applying changes or permutations to rows, that can be implemented in a 
computer. Some are neater, cleverer or more efficient than others.

However - sometimes efficiency matters, and sometimes it doesn't. You 
have to bear in mind that even a slow and cumbersome way of applying 
permutations will be measured in nanoseconds on a modern PC. Also of 
course very often we aren't concerned with applying changes or place 
notations to individual rows: in composing programs where speed is of 
the essence we will move far beyond that, to pre-built tree structures 
which allow courses to be navigated between without any permutation 
calculations required whatsoever. This is analogous to a human composer 
working in coursing orders and FCHs rather than pricking out individual 
leads and changes.

So, what we're discussing here is more about the basic building blocks 
than any great conceptual breakthrough. It is however still fascinating, 
to me at least!


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