From cube-lovers-errors@mc.lcs.mit.edu Mon Nov 3 12:42:36 1997 Return-Path: Received: from sun30.aic.nrl.navy.mil by mc.lcs.mit.edu (8.8.1/mc) with SMTP id MAA29514; Mon, 3 Nov 1997 12:42:36 -0500 (EST) Precedence: bulk Errors-To: cube-lovers-errors@mc.lcs.mit.edu Mail-from: From mouse@Rodents.Montreal.QC.CA Sun Nov 2 06:52:25 1997 Date: Sun, 2 Nov 1997 06:51:36 -0500 (EST) From: der Mouse Message-Id: <199711021151.GAA27954@Twig.Rodents.Montreal.QC.CA> To: cube-lovers@ai.mit.edu Subject: Re: Categorization of cube solving programs >> Class 3: A program that when given a specific instance of the >> cube, attempts to [solve it] [eg, Kociemba] >> Class 4: A program which attempts to [find an algorithm to solve >> arbitrary cubes]. > In retrospect, Class 4 programs are not necessarily more > sophisticated than Class 3 programs especially when one considers > that the latter should be be able to produce a macro-table solution > by solving for a sufficient set of specific sequences. Sure...but who picks the specific instances for them? > Richard Korf points out a suggestion by Jon Bently that the learning > program can be be interleaved with the solving program, as > co-routines, and only running the learning program when a new macro > is needed to solve a particular problem instance. This means that the solving program has to imagine macros, try to choose a useful one, determine whether it's actually possible (you gotta keep the program from trying to produce, for example, a single edge flipper). You also have to decide when it's worth trying for a macro and when it's better to just hit the (sub)problem with brute force. I would expect all these problems to be quite hard. >> I wish to speak to the last sentence of the Class 4 description. >> Back in my larval stage (mid-'80s), someone at a lab I worked for >> build a Class 4 program in Franz Lisp. [...] >> I have no idea whether the program still exists in any form. I do >> believe I can still reach its author, if anyone would like me to >> inquire. > It would be interesting to compare the approach of this program to > Korf's learning program. If the program is still available I suggest > it would make a quite excellent addition to the cube lovers archive. I'll send off a missive to the author. der Mouse mouse@rodents.montreal.qc.ca 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B