# Thread: Weekly competition 2007-36 (2,3,3OH,4,5,BF,SQ1,MG,FMC,MM,PM,Relay)

1. I don't understand what premoves are. It seems like they are doing a move in front of the scramble, but that is changing the scramble, so that would not be allowed, would it? (Btw, nice solution Arnaud).

2. No... as long as your solution can solve the scramble given, that's all that matters. You can do whatever you want to scramble (reverse, premove, anything else you can think of) to allow your solution to be better. What's judged is your solution to the final scramble and that's it.

3. I know that, but if you do a premove you are solving a different scramble, so your solution won't match the real scramble.

4. The "pre-move" is part of the solution!

5. Pre-moves are almost the same as setup-moves. If you do a pre-move on the scramble, you will have to undo that move in your solution. If you check my solution carefully you will see that I actually solve the official scramble in the 25 moves. The last move usually undo's the pre-move.

The basic idea is this:
Scramble A can be solved with solution B
If I do pre-move X and then scramble A it can be solved with solution B followed by undo-move X'

It becomes a little confusing if the scramble starts with move X and you use pre-move X' because it looks like you are solving a shorter scramble, but you have to add undo-move X at the end.

6. But if you make a premove based on the first few moves of the scramble, then isn't your solution based partly on the scramble? I thought that that wasn't allowed.

7. Yes. You have to be very carefull not to break that rule! For example you couldn't use the first 10 moves as premoves, solve the remaining 7 moves yourself and then undo 10 moves.

I don't think 1 move is a problem, especially not because we have 2 scrambles (45/optimal) and the first move is different on those scrambles.

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