From cube-lovers-errors@oolong.camellia.org Thu May 29 00:28:22 1997
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Date: Wed, 28 May 1997 15:18:10 -0700
From: Richard E Korf
Message-Id: <199705282218.PAA17014@denali.cs.ucla.edu>
To: Cube-Lovers@ai.mit.edu
Subject: rumor control
Dear Cube-Lovers,
Apparently some work I did recently has gotten badly mangled by the press. I
have NOT resolved the question of whether or not 20 face turns is the maximum
distance one can get from a scrambled cube.
What I did is to write a heuristic search program that finds optimal
solutions to arbitrary scrambled cubes. The algorithm is very different from
the method of Fiat, Moses, Shamir, et al, and seems to be competitive with their
algorithm in terms of time and space. The current version of my program is
practical for cubes up to 18 moves away from solved.
Out of 10 randomly generated cubes, one was solved in 16 moves, 3 required 17
moves, and 6 required 18 moves, suggesting that the median optimal solution
length is probably 18 moves.
A paper on this work will be presented at the National Conference on
Artificial Intelligence (AAAI-97) in Providence, RI in July. I'd be happy to
send a postscript copy of the paper to anyone who is interested, unless there
are a lot of requests, in which case I'll just post it on my web site and put a
pointer here. In addition, if there is enough interest, I could write a short
summary of the paper for this list. Thanks for your attention.
-rich korf