From cube-lovers-errors@oolong.camellia.org Mon Jun 2 13:10:15 1997 Return-Path: cube-lovers-errors@oolong.camellia.org Received: from oolong.camellia.org (localhost [127.0.0.1]) by oolong.camellia.org (8.6.12/8.6.12) with SMTP id NAA03408; Mon, 2 Jun 1997 13:10:15 -0400 Precedence: bulk Errors-To: cube-lovers-errors@oolong.camellia.org From: SCHMIDTG@iccgcc.cle.ab.com Date: Sun, 1 Jun 1997 22:03:44 -0400 (EDT) To: cube-lovers@ai.mit.edu Message-Id: <970601220344.2140c63e@iccgcc.cle.ab.com> Subject: Re: Searching and Metrics in (Korf 1997) Dan Hoey wrote: >The method I suggested for reusing tables for new heuristics should be >applicable to any group-theoretic puzzle for which there are >symmetries mapping generators to generators. For instance, the N^2-1 >puzzles have the 8-fold symmetry D4, and so could have one set of >tables used for 16 heuristics. > >Given the central nature the memory-performance tradeoff plays in the >paper, I imagine this is quite relevant to Rich's research. I suppose it depends upon where one is willing to draw the line with respect to so called "weak methods" (i.e. search techniques that don't rely on information about the problem domain). If the methods are specific only to group theoretic puzzles, I think they are interesting and useful, but somewhat less relevant to advancing the state of the art of weak methods as applied to larger classes of problems. I'm under the impression that Rich's research is focused on the latter, as opposed to the goals of the typical hard-core cube enthusiast. By the way, if someone is aware of a paying full-time research position focusing only on solving the cube, and related, puzzles, please let me know and I'll sign up tomorrow! :) Having said that, I think the table optimization you described is a very clever way to take advantage of symmetries for these types of problems. Eventually, I hope that the knowledge gained by this, and related, threads can be synthesized into a new algorithm that surpasses all previous cube solving program. Now that would be exciting to cube-lovers! -- Greg