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Don't understand a specific notation

Nielsz

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Dec 6, 2006
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Hi,

I'm trying to learn this method: http://grrroux.free.fr/method/Step_3.html

One step says: (R'DR'DR')U(R'DR'DR')'

I understand, R, R' and so on, but I don't understand the last one.
Should I repeat the whole sequence "negatived"? Or reverse the whole sequence, or just untill the last ( ?
 

Athefre

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When I first started learning Roux, I had the same problem.

First you do:

(R'DR'DR')U

Then:

(R'DR'DR')'

Which means do all of the stuff in parentheses backwards, which turns into RD'RD'R since the last parentheses has a ' after it. It's just like algebra.
 
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Nielsz

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Dec 6, 2006
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Originally posted by Athefre@Dec 6 2006, 10:33 PM
When I first started learning Roux, I had the same problem.

First you do:

(R'DR'DR')U

Then:

(R'DR'DR')'

Which means do all of the stuff in parentheses backwards, which turns into RD'RD'R since the last parentheses has a ' after it. It's just like algebra.
Ah, obvious.

R'DR'DR' U RD'RD'R

Should be the whole sequence.
Thanks!
 

BruuD

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Dec 7, 2006
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Originally posted by Athefre@Dec 6 2006, 09:33 PM
First you do:

(R'DR'DR')U

Then:

(R'DR'DR')'

Which means do all of the stuff in parentheses backwards, which turns into RD'RD'R since the last parentheses has a ' after it. It's just like algebra.
Why don't they just write it down in the right order then?
If (R'DR'DR')' is actually RD'RD'R, why don't they just write down "RD'RD'R" ?

btw, 1st post, I R cube n00b :blink:
 

pjk

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They are showing it I guess you can say in "commutator notation". It is written to show how there is a sequence of moves, then a U, and the inverse of those moves.
 

Athefre

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I think he writes them like that to make them easy to remember. You do "this", then you do "this" again but backwards. His whole table is meant to make things easier to remember.

He has on his site in the MISC section how memorizing sequences is the worst thing about cubing.

Also he used to have at the bottom of his Step 3 page something else about memorizing ("My religion (laziness) forbids me to learn how to recognize 69 new cases").
 
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