In Jerry's message from Date: Mon, 16 Oct 1995 23:08:02 -0400 (EDT) Subject: The Correctness of Large Seaches
In light of the above discussion, I thought it might be appropriate
to summarize some background about my larger searches. I want to
indicate which ones of them seem pretty well verified, and which ones
of them might benefit from further study.<U,R> - I believe this one is ok. I ran the q turn case with and without conjugacy classes. Upon expanding the conjugacy classes, the results matched the results without conjugacy classes. Also, the results matched results posted by Mark Longridge as far as they went (although my anomaly with corners-only suggests that such matching doesn't prove very much).
Well, I did get up to 12 q turns deep ;-)
Good enough for 2 half deep searches...
But there is another possible verification method by counting the
number of even positions and odd positions and totalling them.
Analysis of < U, R > group on 3x3x3 cube by Parity --------------------------------------------------Even Positions Odd Positions -------------- -------------0 1 1 4 2 10 3 24 4 58 5 140 6 338 7 816 8 1,970 9 4,756 10 11,448 11 27,448 12 65,260 13 154,192 14 360,692 15 827,540 16 1,851,345 17 3,968,840 18 7,891,990 19 13,659,821 20 18,471,682 21 16,586,822 22 8,039,455 23 1,511,110 24 47,351 25 87 ---------- ---------- 36,741,600 36,741,600
This is almost Cube Philosophy... how can we be certain about the true
nature of God's Algorithm? How can we be certain our cube databases
are completely accurate? I suppose it is not really a big problem
as long as the various cube programs all agree, and a human
observer executes such processes on a real cube.
-> Mark <-