[r-t] applicability and timing (was The null change)

[Don Morrison]

On Sat, Jan 3, 2015 at 3:11 PM, Tim Barnes <tjbarnes23 at gmail.com> wrote:
> Part of method classification: A Beta-Method is a Method whose
> process always produces the same, finite sequence of Changes.

I think for "same" to have any meaning here to you have to be explicit about
the domain that is varying, and over the variations of which the sequence
of changes remains the same.

> I don't think Stage can be defined without reference to stationary
> bells, so it might be cleaner to define Stage at the composition
> level, where methods, calls and stationary bells are first combined.
> I think Stage can be removed from the definition of Method by
> referring to N bells in the definition of Row, as below.

I think we can quickly get into hot water here. If you don't restrict
a method to a particular stage you can end up with a method the
changes of which are of all sorts of different stages. How they
combine would seem to be fraught with peril. And even if methods
can have mixed stages (anyone who believes they can, please pass
me the aspirin), I'm certain we don't want beta-methods to have
them.

I also don't understand what the signicant difference is between
defining stage and saying "N bells". Isn't it just like picking between
saying "pork" or "pig meat"?

> Change: The progress from one Row to the next, effected by the
> interchange of zero or more pairs of bells in adjacent Places in the
> Row.

I think we might be doing ourselves, and posterity, a favor by not
boxing in future acceptance of jump changes, by instead defining a
change to be any permutation, and then explicitly limiting it to
non-jump-changes in beta-methods, or whatever. Otherwise we're going
to end up in a shockingly familiar situation where we'll be defining
"non-change changes" if jump-changes ever become more popular :-)

A fine point, not one I'm going to go to the mat for, but will mention
anyway: I've always been a little surprised by the phrase "effected by
the interchange...places in the row" in the current decision. The
definition is actually talking about the motion from one row to
another, but "in the row" sounds more like to we're doing something
within one of those rows, which one not being clear. I don't think it's
caused any confusion, but perhaps we can come up with a more precise
wording.


-- 
Don Morrison <dfm at ringing.org>
"There was...a single maraca, possibly for use by a Zen
flamenco dancer."                -- Terry Pratchett, _Soul Music_