robin at robinw.org.uk
Thu Apr 23 13:05:32 UTC 2015
Let us be clear on this, method extension is a very easy concept. Any
problems which have arisen in interpretation of the Decision is due to
putting an easy concept into formal language and then trying to
understand the formality. It is rather like this - how would you explain
the colour blue, as in the sky outside my window as I write this, to
someone blind from birth.
Extension is based upon some simple concepts which were laid down in the
early post-war period. I do not wish to go into historical arguments as
to why Ipswich S8 is not a formulaic extension of Ipswich S6 and I have
no problem with historical anomalies. Some of these basic concepts are
preservation of class (surprise always gives surprise), preservation or
not of PB lead heads and what might be called contiguosity. This means
that you would expect an extension of Cambridge to have 2nds place made
somewhere below the treble and 3-4 places made above the treble in
Oxford, as examples.
Further, these concepts were based upon what had been rung and claimed
as extensions at the time. I've remarked elsewhere that it might have
happened that the 'antients' might have rung what we call Yorkshire S10
and called it Cambridge instead. It is quite easy to justify this.
As is always the problem with 'simple' concepts, it is translating these
into some sort of formula and back again. The man who knows most about
the formula is the man who generated it in the first place. It's the
rest of us who have to try to understand it.
Strange as it may seem, some of us on the Methods committee have
concerns over the requirements in (G)B. I wonder about the desirability
of (G)B1 - if only for practical reasons. (G)B5 is one which has caused
comment in the past, w.r.t the extension of Surfleet S6 for example.
Speaking from memory, RDB remarked that there is an extension at every
stage but is regular only at stages divisible by six. (I haven't checked.)
Tim Barnes asks about (G)C2(b)i. Consider the extension of Writtle TB6
- which is Kent TB with additional 3-4 places made when the treble is in
5-6, so the work below the treble is x2x184.108.40.206.1. These two parts of
the Decisions allow: x2x220.127.116.11.18.104.22.168.1 or
x2x22.214.171.124.126.96.36.199.1 or x2x188.8.131.52.184.108.40.206.1 or x2x1x2x220.127.116.11.1
but not x2x1x2x18.104.22.168.1
Also, (G)B6 is designed to stop the extension of a method which has at
most two blows in any one place becoming three blows - see Beverley S8
In a case like this, examples are everything - a criticism which could
be made of mathematics text books. I revised the Extension document some
time ago - we just haven't got around to publishing it although one
member of this list did receive a copy by request - didn't you?!
This drew on a complete set of extensions of both TD and Plain six-bell
methods given to me at least ten years ago and this is acknowledged in
the document. In the set, there are thirteen formulaic extensions of
Surfleet S. Minor, six which terminate and the rest are *thought* to be
indefinite. Two start at stage 10 and increase by four, two at 12 by
six, one at 12 by eight, one at 18 by 12 and the one Tim asks about to
28 and then 52.
It is worth why this process was started in the first place. To stop
arguments by giving an objective rule for extension. By and large, it
has achieved that purpose.
b.t.w, if you try extending Single Oxford B6 to seven, you will readily
see the efficacy of (G)E
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