[r-t] New mirror principles

[Rob Lee]

On Thu Feb 4 21:56, GRich wrote:
>I produced what is probably the simplest principle to use these three place notations, and called it Horizontal Major:
>Horizontal Major
>18.36-36-18-36-36-36-18-36-36-36-18-36 31527486

There was some discussion on this list back in November 2012 along similar lines. I had come up with the following principle:
36.18-18.36-, 18 (24163857)

This has a plain course of 96 changes. I didn't realise at the time, but the plain course together with a partner course (headed 16754238) contains all the elements of that same group of order 192, so there will exist 420 courses that together give the extent.

Probably the best known major principle using those 3 place notations is Duffield, whose plain course together with, again, its partner course headed 16754238 gives half of the same group, and a complementary principle swapping the place notations (-1-1-36) can be used to obtain the other half. So, in theory, you should be able to generate an extent splicing these two principles in whole courses. I'll leave the composition as an exercise for the reader...

Rob