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Date: Sun, 01 Jun 1997 18:35:50 -0400 (EDT)
From: Jerry Bryan
Subject: Re: Description of algorithm for finding minimal-move solutions to
Rubik's Cube
In-reply-to: <338F7124.73A6@hrz1.hrz.th-darmstadt.de>
To: Cube-Lovers
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On Sat, 31 May 1997, Herbert Kociemba wrote:
>
> In phase 1, the cube is transformed to an element of the subgroup
> generated by __.
.....
> The "heuristic functions" consist of three tables, using 4
> bits for each entry. The first table stores the minimum numbers to solve
> the 2187*2048 possible states to restore the orientation of both edges
> and corners, the other tables have 2187*495 and 2048*495 entries and
> store the corresponding minimum numbers.
Obviously, any conjugate of ____ would do as well as any
other. Have you looked for conjugate positions in your table? For
example, you might have a position x which is 10 moves from
____, but position y which is a conjugate of x might be only
be 9 moves from ____. In this case, you might as well solve
y, knowing that the number of moves to solve x is the same as the number
of moves to solve y, and knowing that the solutions are conjugate. Also,
by subjecting your entire table to this kind of analysis (if you haven't
already), you might find an upper bound for stage1 which is less than 12f.
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Robert G. Bryan (Jerry Bryan) jbryan@pstcc.cc.tn.us
Pellissippi State (423) 539-7198
10915 Hardin Valley Road (423) 694-6435 (fax)
P.O. Box 22990
Knoxville, TN 37933-0990
__