[r-t] The null change

[Don Morrison]

On Tue, Dec 30, 2014 at 8:59 PM, Matthew Frye <matthew at frye.org.uk> wrote:
> I struggle to see why so many seem to have such a conceptual problem
> with this.

It's nice to know I'm not the only one who so struggles. :-)

> should really be concerns about falseness (which I'm sure will be a
> thrilling discussion to be had sometime in the coming months).

I don't recall whether or not you were a member of this list when last
we discussed that. If not, you could look it up in the archives. It
was a memorably convoluted discussion, that eventually fizzled out.
One of the benefits of the current exercise may be it will give us a
firmer foundation from which to restart that and maybe even reach a
conclusion this time!

>> All the sequences of changes generated by a method must include at least
>> one non-null change.
>
> Do you really think that's necessary?

Personally, no. If someone wants to do something daft it really
doesn't bother me at all. However, I suspect allowing rounds to be a
method is just going too far for many folks, and it is sufficiently
perverse that I'm equally unfussed if we choose to prevent it, which
seems likely.

> Why not allow someone to define a methods composed entirely of null
> changes? If they can compose something true with it, then good on
> them!

240 Spliced Minimus
1234
____
2143  BA
2413  CA
4231  BA
4321  CA
3412  BA
3142  CA
1324  BA
1342  DA
____
Repeat twice.
Method A = 1234.1234.1234.1234.1234.1234.1234.1234.1234
Method B = x
Method C = 14
Method D = 12

or

240 Daft Super-Placey Minimus
1234 1 2 3 4 5 6 7 8
____________________
1342 x - x - x - x s
____________________
Repeat twice.
- = 14
x = x
s = 12
Method: 1234.1234.1234.1234.1234.1234.1234.1234.1234.1234

Similar constructions are trivially easy to construct for doubles or minor,
but require way too much typing!

> I'm not convinced that ringing things in whole pulls is the same as
> allowing use of the null change.

It's not the same, but null changes in a method allow you to do it
(and name the result as a distinct method). For example, this treble
place minor method:
123456x123456.16.123456x123456.16.123456x123456.16,12 [that's a
comma, not a full stop, between the 16 and the 12]. W,sW,W,sW,Hx3 is a
true (in the MEB sense) 1,440.




-- 
Don Morrison <dfm at ringing.org>
"Most writers--poets in especial--prefer having it understood that
they compose by a species of fine frenzy--an ecstatic intuition--and
would positively shudder at letting the public take a peep behind the
scenes, at the elaborate and vacillating crudities of thought...which,
in ninety-nine cases out of the hundred, constitute the properties of
the literary histrio."
       -- Edgar Allen Poe, "The Philosophy of Composition"