# Accounting for Parity in Memorization



## Musturd (Mar 9, 2009)

I have not solved a cube blindfolded yet, though I can solve it with old pochmann while looking, so maybe this wouldn't work, but...

At least for Old Pochmann (centers and edges) if there is an odd number of permutations there is a parity. Say you memorize edges first, realize there is an odd number of permutations to do, so you swap two corners in your corner memorization.

For example:
Scramble: F R2 F R U2 L2 R' D' B L U' R D U L D B2 F D F2 L2 F2 R D2 U'

(Eric Limeback's way for memo)
Edge Memo: "VJH XMRPX TLS" 
Corner Memo: W(DBL-corner) , B(UFR-corner), *B(DFR-corner)*, G(UFL-corner)... etc.

I notice now, that it would be easier to start with corners and adjust edge memorization rather than corner because of the strange sticker swapping of the Old Pochmann edge algs.

Is there any reason, why I should NOT do this parity fix in memorization?

EDIT: Oops, I either solved it wrong or memorized it wrong, but I think I messed up somehow, but not because of the parity fixing in the memorization. Don't assume this example to work.
EDIT2: I think my memorization doesn't match my scramble either


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## Gparker (Mar 9, 2009)

all you do is the R perm after edges or corners and you did an odd number. and you just tell yourself you have it and thats it, your not allowed to turn the cube during memo


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## Musturd (Mar 9, 2009)

Doing the R-perm twice is a waste of time because it can be accounted for in memorization, right?
Basically, that question is the whole point of this thread.


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## Gparker (Mar 9, 2009)

what? you only have to do it once unless you use M2, you can memo around it but that would be harder


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## tim (Mar 9, 2009)

Musturd said:


> I notice now, that it would be easier to start with corners and adjust edge memorization rather than corner because of the strange sticker swapping of the Old Pochmann edge algs.



Why do you have to adjust your memorization in the first place? I don't really get it.


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## joey (Mar 9, 2009)

Sure, you can do it. I've done it before.


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## byu (Mar 10, 2009)

OK, I understand now.

The question is that wouldn't it be faster if you didn't do an R-Perm for parity and just memorized UFR and UBR swapped. So when you want to see what is at FRU, you really look at RBU, RUF to BRU, UFR to UBR, and vice versa.

My answer is that yes, it's possible only if you use old pochmann, with M2/R2, it doesn't work that way. If you use M2/old pochman with corners first, then it works (swap UL and UB), with edges first it doesn't. Plus, it's harder to memo, so although you'll have a faster execution, you may have a slightly longer memorization.


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## fanwuq (Mar 10, 2009)

I never do R perm, it's just stupid. It can actually be any alg that swaps the edges, so it could be doing J or Y perm again; but why? Just leave the last corner to finish later after you finish the edges.
I do not treat it as a special thing to memo. I do visual corners and count while memorize; there's no need to waste memory.


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## DavidWoner (Mar 10, 2009)

Gparker said:


> what? you only have to do it once unless you use M2, you can memo around it but that would be harder



you only have to do it once when you use M2 as well, just do U' F2 U M2 U' F2 U


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## mrCage (Mar 13, 2009)

Why do you need to know offhand if the scramble is in an even or odd state? As you go along solving the cube, no matter what method - you will eventually realise it and do the appropriate fix. Turning an odd position to an even position in the beginning of a solve. I do not see the benefit to be honest:confused:

Per


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## Gparker (Mar 15, 2009)

Vault312 said:


> Gparker said:
> 
> 
> > what? you only have to do it once unless you use M2, you can memo around it but that would be harder
> ...



with M2 old pochmann and corners first you do it twice, once if you have parity after corners, then after edges you do U' F2 U M2 U' F2 U then the r perm again


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