[r-t] Ben Constant's Yorkshire Royal
mark at snowtiger.net
Wed Jan 14 18:28:28 UTC 2009
> In any case, it would seem difficult to extend the invariant under
> rotations and reversals case to this unambiguously, when no one has
> actually written down the entire block that is being rotated or reversed.
Yes. Although if you're comparing a snap-finish composition to a round-block
composition, it should be fairly obvious when the snap-finish one contains
everything in round-block bar maybe a finishing single. On the other hand,
you are right, if there's a lot of stuff in the snap finish one that the
round block doesn't contain, well it would be very reasonable to argue that
they are separate. This is again a question of degree: how much stuff is new
in the snap-finish arrangement?
I had one the other day where two snap-finish compositions appeared
reasonably to be rotations of each other. How can that be? Well, they were
both regular three-parts, that would have come round normally at something
over peal length, and both then been rotations of each other. In order to
shorten the length, both composers had added a single Wrong at the
appropriate place in the last part, to bring up rounds at the snap. Because
of the transpositions involved, it so happened this could be done in both
compositions at the same place.
(If you want the full details, it was Dale Barton's 5058 of Yorkshire Major.
Each part is H, sMsH, sW3H, sWsH, sMH, WH. A sW after the last sM in the
third part brings up the snap finish. Now John Ridley had rotated the part
to start in the middle of the 3H block: 2H, sWsH, sMH, W2H, sMsH, sWH. Guess
what - a sW in the same place still brings it round. The changes rung and
the part ends are different, so why does this work? Because the calls after
this sW in both compositions produce the same permutation: HWH = sHsWH.)
The case here seems pretty clear: both compositions are shortened multipart
round blocks, the multiparts are rotations of each other, and the shortening
calls are identical.
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