Message #1093

From: Klaus Weidinger <klaus.weidinger@yahoo.com>
Subject: Re: [MC4D] 3^4 in 237 twists
Date: Tue, 27 Jul 2010 14:39:15 -0700

Hi Jonathan,

nothing to apologize for. God’s number is the number of moves you need to solve
the cube from any given state. For example, it is very likely that God’s number
for the normal Rubik’s is 20. Every position that has been tested up to now
could be solved in 20 twists or less and it is mathematically proven, that no
state of the cube is more than 22 face twists away from the solved state. This
is a very low move count, but not out of human range, because out there, some
guys have already solved the cube within 19 moves.

For the 3^4 God’s number is at least 56 as computed by Andrey and I expect it to
be anything from 58 to 62. And I’m quite optimistic that someday we will be able
to solve a 3^4 optimally with a computer. I might take SOME more years (those
programmes are not even developed, nor are our computers capable of this task
yet), but I think we have a good chance to get this done within our lifetime.
But I just can’t imagine that there will ever be some human being able to solve
the 3^4 with a move count this low. Therefore, in my opinion there have to be
seperate categories for humans and computers in fewest move solving, even if the
latter ones do not even have entered the "competition" yet.

You also asked how computers solve a 3^4. Well, at the moment, they don’t do it
at all, but if they will ever do, they won’t use MC4D, because I expect the
graphical user interface to be kind of cumbersome for them ;-) But if you want
to understand how a computer can solve a Rubik’s I would suggest having a peek
at the manuals and FAQs of CubeExplorer. They are quite informative. This should
also answer your last question on how programmers are solving a Rubik’s.

If you want to know how I solved the 3^4 with so few twists you will have to
either search the archives (you will find a very rough description of my
method), or have to be a little bit patient, because I’m going to put some
precise descriptions of my methods on the wiki. Before that, I will, however, do
some more solves, which may take some time.

Happy Hypercubing,
Klaus

________________________________
From: Jonathan Mecias <jonathan.mecias001@mymdc.net>
To: 4D_Cubing@yahoogroups.com
Sent: Tue, July 27, 2010 4:13:56 PM
Subject: Re: [MC4D] 3^4 in 237 twists

Klaus, thanks for you honesty and respect for Mathew’s solution.

"because in 4D I expect god’s number to lie out of human range unlike in 3D.
Therefore there should be two records. One for humans and one for computers."
-Klaus
What do you mean by this? and gods number? how do computers solve this? Won’t
that mean that programmers solve it using the aid of other people and computers
and math?

how did you manage to get the solution so low even without the computer help in
solving the 3x3x3? I’m curious now. Is there a thread on this in the archives? i
apologise for my incoherent questions.

jonathan

On Mon, Jul 26, 2010 at 9:31 PM, Melinda Green <melinda@superlimina l.com>
wrote:

>Klaus,
>
>I don’t mean to assert that a solution is computer-assisted simply
>because the puzzle is implemented in software. In the case of MC4D the
>most obvious forms of assistance are undo/redo and the macro facilities.
>The piece finding tool in Magic120Cell is another obvious computer aid.
>I also consider the reset command to be a computer aid. You can see how
>intelligent minds can begin to disagree about just what constitutes an
>aid and the degree to which those aids should or should not matter when
>comparing solutions.
>
>I’ll continue to maintain the existing record categories in the HOF but
>please feel free to create and curate any new categories on the wiki
>that you feel motivated to maintain.
>
>Congratulations on your amazingly short solution BTW,
>-Melinda
>
>
>Klaus Weidinger wrote:
>>
>>
>> Hi Melinda,
>>
>> I don’t really understand what you mean by "all 4D solutions are
>> computer-assisted to one degree or another". Well, of course you need
>> a computer, because otherwise you can’t run MC4D, but that is no
>> assistance, yet. In my first solve I only used a pen, some sheet of
>> paper, a regular rubik’s cube and one pocket cube. In my second solve
>> I computed one PLL alg for the 3^3, but if I had known 2-look Fridrich
>> and used the same alg or looked it up on the internet, there wouldn’t
>> have been any difference. Therefore I would not call my first two
>> solves computer-assisted.
>> My third solve, however, is computer-assisted, because I would not
>> have been able to solve a 3^3 in less that 30 twists.
>>
>> Concerning the categories, I would suggest the following three:
>> - Without any help of a computer
>> - Computer-assisted
>> - Completely done by a computer
>>
>> If you don’t want to maintain these, I could do the job for now.
>>
>