Date: Thu, 08 Jan 81 20:06:00 -0600 (CST)
~~~ From: Bill Vaughan <VaughanW.REFLECS@HI-Multics >
~~~ Subject: Befuddled by BFUDLR

This is a plea for another notation.

BFUDLR is sufficient to describe anything. So what? It's about as
student, and (my particular gripe) it's impossible to express an
elegant sequence in it and keep any of the elegance.

I want to keep this short, so I'll only give a few examples. The
first is the Sprat Wrench. BFUDLR calls it: RL'URL'BRL'DRL'F. But
the way most everyone does it, it's: (XU)*4, where X means "move
the LR slice clockwise as viewed from the left."

The next example (I don't know its name) flips all top and bottom
edges. BFUDLR calls it: LRUDFBLRUDFB. Interesting, but this is
nicer: (R-B-)*3, where "foo-" means "foo antislice" and is done by
twisting foo and its adjacent slice clockwise 1qtw, then twisting
foo another qtw.

A move yielding (RF, BL, RB) has been published (Don Woods 6 Jan
81) in BFUDLR as: BRL'D'RRDR'LB'RR. Now where's the symmetry in
that? But annotate the same move BXB'RR.BX'B'RR (X as in first
example) and you can see how pretty it is. And it's a lot easier
to remember.

The key is that the fixed orientation of the center cubies
shouldn't be a sacred cow. Often, keeping a corner cubie as a
fixed point will yield a far more natural notation.

The commonest compound moves: slice, antislice, and possibly
Singmaster's Y and Z commutators, should have specialized
notations. A move that I use commonly in solving the cube is a
monotwist: Y(f,r)*2.L.Y'(f,r)*2.L'. That's a lot harder to
understand as: FR'F'RFR'F'RLR'FRF'R'FRF'L'.

I don't have good notations to offer for slice and antislice. What
I do with paper and pencil involves overstrikes that my CRT can't
handle. Something nice and linear is needed, with all the
characters in ASCII. Any suggestions, anyone?