[r-t] A new Spliced Surprise Major canon
mark at snowtiger.net
Mon Mar 4 08:04:04 UTC 2013
I've been thinking for some time that more work needs to be done in the
field of "ordinary" spliced - by which I mean the straightforward stuff
with tenors together and familiar methods, the sort of thing that gets
rung every day. It seems most of the important contemporary developments
in spliced have focused on the (n-1) or (n)-part, generally with cyclic
part-ends. Of course we have seen some amazing progress here, with Alan
Reading providing us a fabulous example only recently.
However, sadly, many peal bands don't ring this sort of stuff, at least
not regularly. You're much more likely to see peals of 4, 5, 6 or
8-spliced in standard methods, and here the choice of composition seems
to lag far behind that of the single method. In fact, you could say that
not a lot has happened since Pitman produced his spliced series in the
1940s and 50s: everything is based on CRUs, and it seems difficult to
source a composition with a good selection of little-bell music.
To my mind, that's unacceptable. OK, composing spliced is hard, and
Pitman was brilliant, but his compositions are sixty years old and more,
and, with the tools now at our disposal, we really ought to be able to
do better. So I've made a stab at setting a new standard for the genre.
My starting point was the idea that I could take a good, simple,
single-method composition, and add methods to it gradually, to produce a
series from "1-spliced" up. As the seed composition I chose my 5056 no.1
of Bristol Surprise Major. This has been superseded in absolute music
counts by later peals in my Bristol series, however I still have a
certain fondness for it, and it does have an elegance in its structure
which I thought deserved a new lease of life. It also has very few
calls, which gives a fresh new feel to the spliced arrangements.
In order to "splice up" this basic calling I developed a set of tools
based on what Wikipedia terms "stochastic metaheuristics". This appears
to be a fancy name for a class of algorithms which use a probabilistic
approach to refine a solution through a series of steps. Examples are
the method of simulated annealing, stochastic tunneling, and genetic
searches. All are very different from the traditional brute-force
search, but have proved very successful when applied to spliced.
The key factor for success is choosing the correct scoring metric. For
example, in the genetic algorithm I breed compositions together by
randomly recombining nodes from two parents, and then, in successive
generations, filtering off all but the highest-scoring children. The
score must reflect the desire to maximise music and method balance
whilst keeping ATW counts, length and truth in check. The same is true
for other metaheuristic algorithms. It was quite remarkable how, in
building this new series, I would often find that tweaking the scoring
criteria was enough to open up new fields of previously-undiscovered
compositions. It was almost as if once I knew how to describe a
composition, I could find it.
The other key breakthrough was finding a way to deal with the
discontinuities introduced by the axioms of changeringing. Falseness is
the primary problem. For any of these probabilistic algorithms to
succeed, it is necessary for them to be able to traverse valleys of
lower scores, in order to discover the high-scoring peaks. However, the
best peaks may be isolated by deep moats of falseness. If you venture
into these moats, by allowing the composition to run false, you are
unlikely get back out again. The search drowns.
I addressed this major problem with what I termed a "deterministic
bridge". Continuing the analogy, as soon as the search's boots were
wetted by a step into falseness, I engaged a conventional brute-force
search to permute hitherto unaffected nodes in order to regain truth,
hopefully now on the other side of the moat. It proved to be enough to
implement this in one algorithm only - the method of simulated annealing
- and to engage it only when scores could not be maximised further using
true steps on "dry land".
Further information about the series, and the figures for the
compositions, can be found here:
Note that the methods I have chosen are not primarily designed to
popularise a new "standard eight". (In fact, there are only six of them
for the time being!). I have tried to select examples which are
beautiful and musical in their own right, but they needed to be
familiar, too. For better or worse, I think many bands would be put off
by a collection of methods with completely unfamiliar names and lines.
So I stuck with Bristol and Superlative from the standard eight, and
added Cornwall and Lessness, both of which seem to be rung a lot these
days to single-method peals, and deservedly so. I also wanted a quality
example of a jx method, and here Deva fits the bill. It is perhaps the
least rung of all the methods I have chosen, but since it has featured
regularly on ringing-chat as AJB's favourite method, I hope peal bands
will at least have heard of it. With Bristol above and a neat
right-place below work, it's very pleasant to ring. Finally, Malpas,
from Chandler's 23, adds a touch of sophistication, perhaps.
I hope this series will be of interest to the ringing community, and
that the time is right for something of its ilk. Comments, questions,
criticisms and suggestions welcome.
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