# 4x4 BLD center commutators questions



## rubiksarlen (Aug 25, 2011)

All questions are concerning 4x4 BLD center commutators.

1. For cases like *Ulb > Flu > Ulf* (2 cycles, so cycle becomes *Ulb > Flu > Ulf*), what is the difference between solving like:

*[f u' f'] U' [f u f'] U* compared to *f [u' [f' u' f] u [f' u f] f']* ?

2. For cases like Ulf > Lub > Flu. Is the solution:

U' [b' U b] u [b' U' b] u' U

3. Are we allowed to do 2 setup moves in a commutator?


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## insane569 (Aug 25, 2011)

not sure how you would do this but use the one answer BLD thread
http://www.speedsolving.com/forum/showthread.php?16775-Big-Cube-BLD-Discussion
http://www.speedsolving.com/forum/showthread.php?27353-One-answer-BLD-question-thread.


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## mrCage (Aug 25, 2011)

rubiksarlen said:


> All questions are concerning 4x4 BLD center commutators.
> 
> 1. For cases like *Ulb > Flu > Ulf* (2 cycles, so cycle becomes *Ulb > Flu > Ulf*), what is the difference between solving like:
> 
> ...


 
Please use commutator notation. Your first sequence would be [f u' f',U']. And yes you can have umpteen setup moves to make uo your conjugated commutator.

Per


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## Jakube (Aug 25, 2011)

1.) Ulb > Flu > Ulf
[f u' f'] U' [f u f'] U - This is an optimal one (Ulb and Ulf are used as Interchange, Flu is inserted to Ulf) , I use it, but I´m doing a cube rotation y to avoid the fs. 
f [u' [f' *U'* f] u [f' *U* f]] f' - This isn´t an optimal one. Here you do an f as Setup to get Flu and Ulf as Interchange. Than again Interchange u' Insert Ulb, ...
But you see, that f and f' cancels and you have the excact optimal thing like above. 

2.) Ulf > Lub > Flu - I will explan how I solve this and what I´m thinking while solving. 
Lub and Flu are interchangeable, so the interchangemove is u. So I start inserting Ulf to Lub (I will do a cube rotation before this.) *y' (l' U2 l)* than interchange *u* undo insertion *(l' U2 l)* and undo interchange *u'* and undo rotation *y*. 
So the com is *y' (l' U2 l) u (l' U2 l) u' y*

3.) Sure your allowed, but it´s not necessary. I for instance use a maximum of 1 setup, except there is a case like Urb -> Ulf -> Drf, than I setup with 3 moves: r' F2 r.


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## mrCage (Aug 25, 2011)

1 setup turn is maximum if you commute on an inner or face layer. Some cases may not be good for speed. (Non-intuitive)
The above mentiones case would be (transposed): D' [r' B' d2 B r, U2] D. Longish ...

Per


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## riffz (Aug 25, 2011)

rubiksarlen said:


> All questions are concerning 4x4 BLD center commutators.
> 
> 1. For cases like *Ulb > Flu > Ulf* (2 cycles, so cycle becomes *Ulb > Flu > Ulf*), what is the difference between solving like:
> 
> ...


 
1. The one is uglier to write out and redundant. That's all.

2. Optimal solution is [b' U2b, u] --> y' [l' U2 l, u] y

3. Allowed? Of course, but it's usually not necessary.

EDIT: Wasn't paying attention so my answers have probably already been stated but I'll leave this here for clarity.


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## rubiksarlen (Aug 25, 2011)

so my solution is acceptable, just that its terrible?


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