Weekly competition 2008-41

[guusrs]

One move insertions are always worth to explore. They take very little time.
I can't do odd insertions (transposition of two corners and two edges c2e2) if they are not in the same layer, though, namely because I remember only few algorithms. As I know, there are 17 different 13-quarter-turn such c2e2 algorithms, most of them hard to remember. Long time ago, I collected 46 15-quarter-turn c2e2 that are not isomorphic and all their circular shifts are different. That was without any computer program. I suspect that there are some more of them. Are they practical? Mostly not.

Hi Mirek, 17 different algorithms up to 13 moves for c2e2 is impressive. You still use/know them?
But I don't think it's very useful for 1 hour competition. I use 3 different algs for c2e2, 10 or 11 moves each.

Gus

Don't take me wrong, I have their list but don't remember them. Actively, I use just 4 of c2e2 that are, yes, 10 or 11 face moves.
Mirek

Those c2e2 algs can be useful i guess, but my strategy (if the situation came up) would be like so: insert a turn to convert into edge 3-cycle and corner 3-cycle instead. Finding insertions for those (separately) would be much easier (even if cancellations would not be too good). Inserting that quarterturn may even cancel a turn you did already

Per

Hi Per,

I do not agree. One insertion of a 10/11 move gives often shorter results than 2 insertions of 6 or 8 moves. For me 1 insertion is also faster.

Gus

 

[Mirek]

One move insertions are always worth to explore. They take very little time.
I can't do odd insertions (transposition of two corners and two edges c2e2) if they are not in the same layer, though, namely because I remember only few algorithms. As I know, there are 17 different 13-quarter-turn such c2e2 algorithms, most of them hard to remember. Long time ago, I collected 46 15-quarter-turn c2e2 that are not isomorphic and all their circular shifts are different. That was without any computer program. I suspect that there are some more of them. Are they practical? Mostly not.

Hi Mirek, 17 different algorithms up to 13 moves for c2e2 is impressive. You still use/know them?
But I don't think it's very useful for 1 hour competition. I use 3 different algs for c2e2, 10 or 11 moves each.

Gus

Don't take me wrong, I have their list but don't remember them. Actively, I use just 4 of c2e2 that are, yes, 10 or 11 face moves.
Mirek

Those c2e2 algs can be useful i guess, but my strategy (if the situation came up) would be like so: insert a turn to convert into edge 3-cycle and corner 3-cycle instead. Finding insertions for those (separately) would be much easier (even if cancellations would not be too good). Inserting that quarterturn may even cancel a turn you did already

Per

Hi Per,

I do not agree. One insertion of a 10/11 move gives often shorter results than 2 insertions of 6 or 8 moves. For me 1 insertion is also faster.

Gus

Yes, time plays a big role here. Also, that one turn Per talks about cancels in all c2e2 that I use. Often two moves cancel as X' X occurs, wich is namely true for "T" and "J" LL permutations, where you can start with either left turn (X') or right turn (X).

Mirek