Talk:Rubik's Revenge

Link

Useless link deleted. Konrad Reif —Preceding unsigned comment added by 141.68.25.4 (talk) 10:26, 21 January 2009 (UTC)

Eastsheen cube

Is the Eastsheen 4x4 legal for tournaments? --M1ss1ontomars2k4 04:49, 26 August 2007 (UTC)

I think it is... —Preceding unsigned comment added by Aceospades1250 (talk • contribs) 03:58, 27 August 2007 (UTC)

Official cube

whats the height of an official Rubik's Revenge —Preceding unsigned comment added by 121.55.202.251 (talk) 21:38, 18 March 2008 (UTC)

2.5 inches or 6.5 cm Masterwiki (talk) 04:17, 8 June 2008 (UTC)

Solve in 2x2 groups

Is it possible to group them and solve like 2x2? Ragnaroknike (talk) 05:19, 17 June 2008 (UTC)

Absolutely! I do this a lot because there's no chance of parity error when it's in 2x2 mode. ;) --$JJOlsen$ 20:36, 17 September 2008 (UTC) —Preceding unsigned comment added by Jjolsen (talk • contribs)

Hey SineBot, it looks like you've been malfunctioning! This comment apparently NOT signed by: -$JJOlsen$ 04:05, 5 October 2008 (UTC) —Preceding unsigned comment added by Jjolsen (talk • contribs)

Odd permutations

According to,

An odd permuation of the corners or edges requires an odd permutation of the centers.
Cubic Circular Issue 7 & 8 David Singmaster, 1985

Which phrase in http://www.geocities.com/jaapsch/puzzles/cubic7.htm#p11, said this?

After I do the sequence,

FrBR2B'r'BR2B'F' r'U2D2l'U2D2r r2u2r2u2

as in 8b of http://www.geocities.com/jaapsch/puzzles/cube4.htm, the result is an odd permutation of edges and even permutation of centers. This can disprove the phrase,

An odd permuation of the corners or edges requires an odd permutation of the centers.

?

--Ans (talk) 08:48, 11 February 2009 (UTC)

Hmm, I've just modified the above sequence as followed,

l2F2d2
FrBR2B'r'BR2B'F' r'U2D2l'U2D2r r2u2r2u2
d2F2l2

This modified sequence will produce an odd permutation of edges without any permutation of centers, like this,

--Ans (talk) 13:21, 11 February 2009 (UTC)

Don't forget that an odd permutation of centres can be hidden by moving it all to one face. The centre cubies can be in an odd permutation but it is not visible because the cubies are not distinguishable. However, it is rather easier to prove the opening claim false. Any slice move is a 4-cycle of edges and 2 x 4-cycles of centres. A 4-cycle is an odd permutation so any quarter-turn slice move is an odd permutation of edges and an even permutation of centers. Immediate counterexample in one move!

I think you are misreading the Cubic Circular page. It makes two general statements of parity;

• The parity of diagonal centres must match the parity of corners
• The parity of non-diagonal centres must match the parity of corners + edges

Rubiks Revenge does not have the second type of centres so only the first theorem applies. This theorem can be seen to be true because any face move is a 4-cycle of corners and a 4-cycle of centres. There are also 2 x 4-cycles of edges but these have no bearing on the theorem. The only other possible move is a slice move which can only produce even permutations of centres and does not affect corners at all. Slice moves cannot, therefore, change the corner/centre parity.

SpinningSpark 21:22, 12 February 2009 (UTC)

Another way to test the given example would be to somehow mark the centers so that you could tell them apart. Picture this 5×5×5 sticker pattern reduced to 4×4×4. Each center piece has extra color(s) relating to which face(s) it is closest to. I suspect that the two examples in the article would have two different center parities.

• The example of two edge pairs being swapped could be done with an even permutation of centers, since the corner and edge parities are both even.
• The example of a single edge pair being swapped would likely have an odd permutation of the centers as well.

I may actually try this myself. Hellbus (talk) 22:25, 12 February 2009 (UTC)

That's not right, the edge parity is odd, it is a swap of one edge pair, not two. So by theorem 2 above the centre parity must be odd also, but invisibly so. SpinningSpark 00:42, 13 February 2009 (UTC)

Making the permutations visible (by marking the centers in some way) is what I was referring to when I said I'd try it myself. Hellbus (talk) 00:45, 13 February 2009 (UTC)

Sorry, I read you wrong, I thought you had said the diagram had two edge swaps, but now I read your post again I see that's not what you were saying. SpinningSpark 00:50, 13 February 2009 (UTC)

There are only two basic types of move: a quarter-turn of an outer slice and a quarter-turn of an inner slice.

• A quarter-turn of an outer slice gives an odd permutation of corners, an even permutation of edges and an odd permutation of centres.
• A quarter-turn of an inner slice gives an even permutation (namely the identity permutation) of corners, an odd permutation of edges and an even permutation of centres.

You don't need to find specific examples of sequences that change only the edges or only the centres/corners. You just need to apply the basic rules on combinations of odd and even permutations; the result is that you can independently change the parity of the edges, but the parities of the centres and corners are tied to each other.

Consequently, Rubik's Revenge with the centre squares made distinguishable has six universes. -- Smjg (talk) 10:57, 13 February 2009 (UTC)

A quarter-turn of an inner slice gives an even permutation (namely the identity permutation) of corners, an odd permutation of edges and an even permutation of centres. <-- This means that, the odd permutation of edges does not require the odd permutation of centres. So, I should correct this article, accordingly. --Ans (talk) 14:32, 13 February 2009 (UTC)

Picture this 5×5×5 sticker pattern reduced to 4×4×4. Each center piece has extra color(s) relating to which face(s) it is closest to. (Hellbus (talk) 22:25, 12 February 2009 (UTC))

Just having the direction marked on every piece (as seen in the above picture ) is enough to distinguish the face centers. --Ans (talk) 14:09, 13 February 2009 (UTC)

There turns out to be another way to test the theory. The V-Cube 6 can be used to simulate a 4×4×4 if you don't turn every layer. For this diagram I've substituted gray for black for contrast purposes. If you only turn the cube along the cuts with bold lines, the cube becomes a 4×4×4 with different proportions. Each 2×2 set of centers is distinguishable. The two pieces along the face diagonal are the same color as the face, but the other two have the colors of the two adjacent faces, and thus each one is different.

I set up this pattern and then set out to "solve" the cube into a position similar to the diagram above, i.e. a single edge pair reversed. I was still able to put all the centers in the correct position. It surprised me a bit.

It's also possible to do something similar with a V-Cube 7 to simulate a Professor's Cube with distinguishable centers, except that the fixed centers won't have an identifiable orientation. Hellbus (talk) 22:05, 15 February 2009 (UTC)

That's a beautifully complex way of doing it Hellbus! What's wrong with just small coloured stickers on one edge of the cubies on a normal 4x4x4? I find that the little vinyl roundels used for manual pcb artwork are ideal for the purpose. SpinningSpark 00:44, 16 February 2009 (UTC)

It's a simple question of availability. I don't have any of those roundels, but I do have a V-Cube set on my desk. Hellbus (talk) 00:48, 16 February 2009 (UTC)

Dear User:Hellbus,

I'm still waiting for the answer of my first question above. Which phrase in your reference, said about this odd permutation of edges?

--Ans (talk) 12:01, 17 February 2009 (UTC)

I probably just misread it. Hellbus (talk) 14:43, 17 February 2009 (UTC)

Inconsistent spellings

There are (or were before the edit I just did) inconsistencies in the spelling of this article; the middle facets of the faces were spelled "centre" in some cases and "center" in others. I've gone through and changed all the latter (in line with the Rubik's Cube article) to "centre".

I believe one of the Wikipedia guidelines is that spellings within one article should be consistent, i.e. all British or all American. It certainly looks sloppy to have a mixture. I propose that this article be standardised on British English, as this is the standard which has been chosen for the Rubik's Cube article. — 79.121.135.185 (talk) 15:38, 2 November 2009 (UTC)

Works for me. My only question is where to draw the line. All Rubik's Cube variants? All Combination puzzles? All puzzles? Only puzzles of european origin? - Richfife (talk) 16:11, 2 November 2009 (UTC)

There's a wiki guideline somewhere (can't find it at the moment) that says that it should be consistent within an article, but changing the style in an entire article is unnecessary. Hellbus (talk) 23:41, 2 November 2009 (UTC)

The guideline you are looking for is the Manual of Style, specifically, WP:ENGVAR. This ays "the variety chosen by the first major contributor to the article should be used". I reverted the recent change on the grounds that the spelling system should not be gratuitously changed, but having now looked at the early edits for this article I see they were all in British English so I will now undo that. SpinningSpark 18:41, 4 November 2009 (UTC)

Color?

The caption under one of the pictures is as follows:

Early Rubik's Revenge cube. The colour layout differs from the standard 3x3 cube.

I don't believe there is/was a standard color layout for the 3x3x3 cube. While all cubes had the same six colors, the placement could differ. SlowJog (talk) 03:17, 9 December 2009 (UTC)

I've changed the caption to avoid this. Hellbus (talk) 03:12, 11 December 2009 (UTC)

Methods

Hi. My name is Josef and I'm a speedcuber from Sweden. Please don't delete the stuff i write about what kind of methods there are and how they work. The current text about methods does not make a of lot sense. I think it would be better to just explain the reduction method, which, in the end of the day, is the most used method for solving big cubes. I have participated in official competetions so I think I know what I'm writing about... Thanks! :) Swedishcuber (talk) 17:36, 10 January 2012 (UTC)

Thanks for your contribution Josef, but I think you need to familiarise yourself with some of Wikipedia's policies and guidelines before you go on. Most importantly, we do not accept contributions as being reliable just because the person providing them claims to be an expert. We have no way of verifying this. Rather, verification policy relies on citations to reliable sources. Follow the link to see what we consider reliable sources to be, but these do not include open wikis, including our own. Further Wikipedia is not a how to guide - our aim is not to teach readers to solve the puzzle. You might also want to consult our guideline on external links. SpinningSpark 19:33, 10 January 2012 (UTC)

Well,sir.... Do you have any source for the two last methods described in the article? I know that they exist, but I don't know anyone who uses them and also, not even the speedsolving wiki mentions it. What are your reliable sources for those methods? It's kinda funny that you delete what I wrote because you consider me to be not reliable. My point is: Why do you delete the stuff that I wrote, I can give you sources for what I wrote and I can prove it to be true, but you don't have any sources for what's written in the article. ... xd Swedishcuber (talk) 17:28, 11 January 2012 (UTC)

Your contribution was reverted as much for the way it was written as the actual content (WP:HOWTO). You are not being accused of not being reliable, the point is verifiability (WP:V). You say you can provide sources but you have provided no references (WP:RS). I am not convinced that you have yet actually looked at the guidelines I have linked to. Please do so, and, if you are able, base your argument for inclusion on Wikipedia policies. If your point is that you do not like Wikipedia policies then this is the wrong page for that discussion, you want a different page entirely. The concern that material already in the article might be unreliable, is unreferenced etc it beside the point. This discussion is about your contribution, which stands or falls on its own merits, regardless of what else is on Wikipedia - see WP:OTHERSTUFF. It is also worth pointing out that this article is not about speedcubing, and what may apply in the speedcubing community does not necessarily apply elsewhere. SpinningSpark 18:38, 11 January 2012 (UTC)

Swapping just two corners

It seems to me that there is another swap-combination which is possible on the 4X4X4 but not on the 3X3X3 ... namely, on a 4X4X4 it is possible to exchange just two corner-pieces - without disturbing anything else... Do you agree? --DLMcN (talk) 12:24, 2 March 2012 (UTC) >>

Actually, (reading the discussion on the Talk-Page) it sounds as if the centre-pieces will get disturbed, even if on most puzzles a permutation of centre-pieces is not immediately obvious--DLMcN (talk) 12:29, 2 March 2012 (UTC)

Turning one of the outer layers causes an even permutation of the edges (two odd cycles) and an odd permutation of the corners and centers. If the center pieces are marked, it becomes impossible to swap two corners and nothing else. With unmarked centers they are still permuted, but this cannot be seen. Hellbus (talk) 06:32, 4 March 2012 (UTC)

Outdated Title

The Rubik's Revenge is a very old cube. If you want to give it it's own wikipedia page, that's fine, but it's wrong to include all 4x4 information on this page. The Rubik's Revenge is outdated and unused. It hasn't been used at a competition for many years, and this page should reflect that. Calling this page "Rubik's Revenge" is misleading and a bad idea. — Preceding unsigned comment added by Hadofhfo (talk • contribs) 16:07, 5 April 2019 (UTC)

The article is named for the first 4×4×4 cube introduced, just as the name Professor's Cube was only used for the first 5×5×5 cubes. There really isn't a compelling reason to change it. Hellbus (talk) 04:06, 6 April 2019 (UTC)