[r-t] Complexity of extents
holroyd at math.ubc.ca
Fri Jun 28 13:24:06 UTC 2013
I vaguely remember that PABS had an extent of the principle
126.96.36.199.7.1.345 with calls 3 and 5 that exploited an unusual kind of
symmetry. (Perhaps he would care to remind us).
On Mon, 24 Jun 2013, Richard Smith wrote:
> Andrew Johnson wrote:
>>> From: Richard Smith <richard at ex-parrot.com>
>>> But when I try to get an extent with rotational symmetry, it
>>> feels like I'm fighting against the symmetry rather than
>>> utilising it.
>> It's not an extent, but for rotational symmetry were
>> you thinking of compositions such as Ander's 5024 Bristol S.
> Not really. I think the difference between an extent an eighth-extent (a
> peal of major) is significant. I was thinking more of extents on four, five
> or six. I can't say I've ever tried to produce a rotationally symmetric
> peal of major.
> Naïvely you wouldn't necessarily expect a rotationally symmetric extent to
> be any harder to produce than a palindromic one. Both symmetries constrain
> half of the rows. But, at least in my experience, a rotationally symmetric
> extent (that's not also palindromic) feels a much tougher proposition than a
> palindromic one.
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