# When to do parity?



## andrewvo1324 (Feb 3, 2008)

ok so im watching grintoth's tutorial for bld...

and he said something about odd numbers you need parity?

is it odd numbers of numbers you memorize for Corner placemnt...

or the number you put your last corner in?


Can someone help me....Exlpain when to use parity and how to fix parity


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## rubiks to the third (Feb 3, 2008)

If you permutate corners before edges, using J PERM most of the time, the number of times you switch corners must be even. If it is odd, then two edges will be switched which you have to factor into memorization.


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## andrewvo1324 (Feb 3, 2008)

So say my memo is

5 4 3 6 2 6 1 6 2 7 2 ( FAKE)

11 times... that means i gotta do parity?

and i also perm corner using L U' Ri' U L'U2 R U' R' U2 R


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## amateurguy (Feb 3, 2008)

That corner perm is one of the many variations of the J-perm alright. 

And parity for this case is used when you're done with corner permutation and moving on to edge permutation. So let's say that your memo for corners is odd-numbered (as above), you apply the parity fix (another J-perm), and move on to edge permutation. 

Simple really.


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## andrewvo1324 (Feb 3, 2008)

Wow....So first i have to do a memo then i have to count how many i do...

that sucks


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## joey (Feb 3, 2008)

No, as you memo them, count the number of edges. Don't count as you are doing the algorithms.


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## amateurguy (Feb 3, 2008)

I agree with Joey on this.


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## andrewvo1324 (Feb 3, 2008)

joey said:


> No, as you memo them, count the number of edges. Don't count as you are doing the algorithms.



you mean corners?


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## joey (Feb 3, 2008)

Well, if you have an odd number of edges, you will have an odd number of corners. So it doesnt matter which you count.


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## andrewvo1324 (Feb 3, 2008)

so basicly i count the edges that are not solved?


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## amateurguy (Feb 4, 2008)

For short: Yes.


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## cmhardw (Feb 4, 2008)

This is one reason why I like memorizing in letter pairs, if you end up with a single piece at the end that does not pair with another, then you have parity. Even easier than counting, as it takes no thought during memo, you just look at how your memorization ends.

Chris


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