# M2/R2 Questions (Parity and R2)



## EricSoha (Jan 24, 2010)

I've recently been learning Pochmann's M2/R2 blindsolving method. I am currently focusing solely on edge permutation and have not ventured into the R2 portion of the solve. Here are my questions.

1.) Odd Parity: I see that this fixes the m-slice. However, I am wondering what the consequences of its affects on the R layer are. I assume the 180 degree rotation of the R layer will be fixed once all the corners are solved (similar to old pochmann where the parity fix switches the UB and UF edges, which sort themselves out as corners are solved). However, it also seems to switch the UFR and DBR corners. Wouldn't this affect your memorization? Some clarification would be helpful.

2.) R2 Issues: I've read that R2 is not the preferred corner method of many advanced cubers. What is the reason for this? Is it because there are so many corners which must be solved via algs and not intuitive set-up/R2/(set-up)' moves, and that this is longer? Is it simply a matter of efficiency or complication?

3.) Compared to R2, how difficult is the 3OP corner method? Can it be simply integrated with M2? How would this affect my first question? 

If you could include some links to some resources which will help me with these questions, I'd greatly appreciate it. Thanks a lot in advance.


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## yoruichi (Jan 24, 2010)

R2 algs are toopid


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## Sakarie (Jan 24, 2010)

EricSoha said:


> I've recently been learning Pochmann's M2/R2 blindsolving method. I am currently focusing solely on edge permutation and have not ventured into the R2 portion of the solve. Here are my questions.
> 
> 1.) Odd Parity: I see that this fixes the m-slice. However, I am wondering what the consequences of its affects on the R layer are. I assume the 180 degree rotation of the R layer will be fixed once all the corners are solved (similar to old pochmann where the parity fix switches the UB and UF edges, which sort themselves out as corners are solved). However, it also seems to switch the UFR and DBR corners. Wouldn't this affect your memorization? Some clarification would be helpful.



Actually, I don't understand your question, but I think that you want to have an explanation of the parity-algorithm.

When you have parity, and memorize edges, you'll always have an odd number of edges. The same with memorizing corners. (If edges are odd, corners always too.)

And when you've solved the edges, you'll end up with a situation where UB and DF is correct, and all the other pieces in the M-slice is off with an M2. Leave it there.

Exactly the same thing with the corners; when you've solved all of them, URB and DRF will be wrong, and everything else off with an R2.

Then you simply just use the parity-alg, for example (r2' U' r2) (R' U) (L' U2') (R U' R' U2 R) (L U') (r2' U) , which completely solves the cube.


> 2.) R2 Issues: I've read that R2 is not the preferred corner method of many advanced cubers. What is the reason for this? Is it because there are so many corners which must be solved via algs and not intuitive set-up/R2/(set-up)' moves, and that this is longer? Is it simply a matter of efficiency or complication?



The reason is because too many of the pieces is laying in the layer your working with, there are too many special occasions, when you can't just [three-move setup] R2 [three-move setup]'. It's simply not fast enough (is the main reason, but of course you CAN be fast with it).



> 3.) Compared to R2, how difficult is the 3OP corner method? Can it be simply integrated with M2? How would this affect my first question?



I haven't actually used neither R2 or 3OP, so I don't know. But if you're just about to learn blindfolded, then I recommend Classic Pochmann, which is the easiest method for almost everyone.

Hope that helped.


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## EricSoha (Jan 25, 2010)

Thanks Sakarie. Your reply was most helpful. 

To clarify your answer to my first question: as long as I perform the parity alg. at the end of my solve, and not mid-way between edges and corners, everything works itself out where there are an odd number of edges/corners, correct?

I already know Classic Pochmann and wanted to learn something more efficient. From your signature, it appears you use BH for corners? What are the pros and cons to this method? What are some good web-sites or other resources where I could learn more about it? Thanks again for your thorough response.


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## Sakarie (Jan 25, 2010)

Yes, what I'm saying is that when you've applied the algorithm, everything will be solved. But that is if you've already oriented URB, or if it was oriented from the start.

BH is hard, but fast. I have no idea who you are or what you can, but the best guide right now is this one, I think.


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## rubiknewbie (Feb 9, 2010)

Sakarie said:


> EricSoha said:
> 
> 
> > I've recently been learning Pochmann's M2/R2 blindsolving method. I am currently focusing solely on edge permutation and have not ventured into the R2 portion of the solve. Here are my questions.
> ...



Oh! So applying that algorithm at the end always works? I also have questions like these and didn't know that if corners are odd, edges are too. Not understanding what the big algorithm does at the end is what discouraged me from learning R2. 

But M2 is nice and I want to use it with another corner method. Then I found Eric Limeback's nice tutorials combining M2 edges with Old Pochmann corners. I think I am going to try that for now! I still have some questions which hopefully can be answered when I try out some examples, like when you fix parity using R perm after corners, you also switch URF and UBF, how do you deal with that?

EDIT: Ok figured it out. Just do another R perm after edges lol. Accidentally found that doing edges before corners is a good idea too.


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## riffz (Feb 24, 2010)

I recommend using Old Pochmann for corners and M2 for edges to ease the transition, then possibly learning a faster corners method later on. From what I've heard R2 isn't very good and I can understand why it would be slow and have quite a few special cases.

Contrary to the post above I much prefer memorizing corners last and executing them first so I can use visual memory.


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## tjyahl (Mar 17, 2010)

i just did my first bld solve a few days ago and i got 5:0.4 on my second successful bld solve so im happy, but i use the t-perm for edges and old pochmann for corners and i feel really slow while executing, i was wondering wat you think the best corner and edge method is out there, i dislike m2 and r2 so dont even bring them into this


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## Simboubou (Apr 19, 2010)

Jean Pons achieved a sub 1 average with M2/R2.

I had used R2 for a while, then I stoped. But the main reason was my being unable to do the "stickers memo". I am far too used to the 3OP memo. But if you can handle the memo and if you had some extra algs to deal with bad case, R2 is actually not so bad.


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## EricSoha (Apr 20, 2010)

Simboubou said:


> Jean Pons achieved a sub 1 average with M2/R2.
> 
> I had used R2 for a while, then I stoped. But the main reason was my being unable to do the "stickers memo". I am far too used to the 3OP memo. But if you can handle the memo and if you had some extra algs to deal with bad case, R2 is actually not so bad.


Thanks for your input Simboubou. I have been working diligently on the M2 portion of my BLD solve and have not yet started practicing the corners. I am concerned about the memo. required by using Old Pochmann (my choice thus far) and am wondering how advanced 3OP is. How does the memo. differ in 3OP? How is it easier? Do you have any good references which I could check out to learn more about this?


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## Simboubou (Apr 20, 2010)

3OP is not so bad : there is cuber (I can't remember his name) who achieved about 1min avg with M2+3OP

With old Pochmann, you have to memorise your corner "with sticker", just as you memorise your edges in M2.
With 3OP, you memorise your corners' position and orientation as two different things. You don't need a "sticker memo". You may find it easier. You can find a whole bunch of algs here (the page is in french, but there are Java applets) : http://www.francocube.com/deadalnix/speedblind.php

This page also have algs for 5-cycles, but since only one person ever really used those 5cycles as far as I know, it is hard to say how fast you can get with this.

Anyway, here is my advice : LEARN POCHMANN FOR CORNERS !
Why ? Because you should definitely get used to the "sticker memo" for corners. Then, you'll be able to switch to an advanced method like TurBo or BH later.

I have used 3OP for corners for almost 3 years now. I wish I could switch to BH, Turbo or R2, but since I am not used at all to the "stickers memo" for corners, it basically means that I have lost my time and that I have to re-learn EVERYTHING. I'll need a lot of pratice before the Euro 2010.

(Unless I manage to learn the 5cycles algs...)


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## Micael (Apr 20, 2010)

Also, keep in mind that you have to memorize that cube! This is an important part of the solve. R2 is good for memory system. I think that only BH is as good as R2 regarding application of memory system. Still, I think that one can ends up with different parity case with BH and that is an extra special thing to memo compared to R2 (with R2, I do not need at all to memorize that there is a parity). With 3OP, you have to memo both permutation and orientation. Oh, and the parity too! 3OP is easier to memorize visually than R2, based on my own experience (and as Simboubou said too), but there is still more information to memorize. That is a real problem with multiple blindfolded. If you aim to learn an advanced memory system, R2 is still a very good choice (otherwise, there is BH, but not for beginner).

Actually, my advice for any beginner in bld is to put more effort on memo technique than execution.

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Edit: I mean "more effort on memory technique than solving method". Obviously, execution should be master for a given solving method, otherwise one would often messed up the cube. I like to do sighted solve for this, like average of 12.


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## Simboubou (Apr 20, 2010)

Micael said:


> Actually, my advice for any beginner in bld is to put more effort on memo technique than execution.



Micael's definitely right. The most important day in my blindfold cubing life was the day I switched to the "story memo method", not the day I switched to M2.



Micael said:


> I think that only BH is as good as R2 regarding application of memory system. Still, I think that one can ends up with different parity case with BH and that is an extra special thing to memo compared to R2 (with R2, I do not need at all to memorize that there is a parity)



True. That is something that bother me with BH : parity can be a nightmare. You can "swap" that parity to UBL-UBR by adding an artificial corner to your memo, but it is not the fastest solution.


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## Mike Hughey (Apr 20, 2010)

Simboubou said:


> Micael said:
> 
> 
> > I think that only BH is as good as R2 regarding application of memory system. Still, I think that one can ends up with different parity case with BH and that is an extra special thing to memo compared to R2 (with R2, I do not need at all to memorize that there is a parity)
> ...


I admit I do that - I swap the parity to UBL-UBR when I'm done. I don't really add the corner to my memo, though - I just know that when I have a single corner at the end of my memo, I want to swap it with UBL-UBR. I find that it doesn't really slow me down, because it's very fast and automatic, since those are some of my fastest algorithms, and I use the time I'm executing that to recall what my first set of edges are. Still, if I ever get better at it, it will certainly cost me several seconds. It's nice and safe for multi, though - I don't have to memorize parity at all. When I get done with the edges, if there's an extra single edge, I know I have to do a T perm at the end.


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