Difference between revisions of "PCMS"

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'''Inspection''', this is the key to success, practice inspection to be able to predict the turns for solving 2-3 pairs and you will have good times.
 
'''Inspection''', this is the key to success, practice inspection to be able to predict the turns for solving 2-3 pairs and you will have good times.
  
Looking for the pieces for the pairs while going is the slowest part of this method so it really pays to be good at predicting the turns. Use what you got, in some scrambles two corners are solved next to each other, pair the edges on the opposite side and then put the corners there using D2 (or use a solver to find algs to put them in directly from some easy to set up to positions). It is possible to pair up more than one pair before you start to place them (this saves turns but is slow if you try to do it on the fly).
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Looking for the pieces for the pairs while going is the slowest part of this method so it really pays to be good at predicting the turns. Use what you got, in some scrambles two corners are solved next to each other, pair the edges on the opposite side and then put the corners there using D2 (or use a solver to find algs to put them in directly from some easy to set up to positions).
  
 
==Pairs:==
 
==Pairs:==

Revision as of 17:14, 27 July 2010

PCMS method
Columns first.gif
Information about the method
Proposer(s): Kenneth Gustavsson
Proposed: 2008
Alt Names: KC (Kenneth's Columns)
Variants: Columns first, Roux, CF
No. Steps: 2 mayor, 2+3 sub steps
No. Algs: 63
Avg Moves: Less than 50 STM
Purpose(s):


PCMS (pairs, CLL, M and S slices) is an advanced method for speedsolving using columns first, designed by Kenneth Gustavsson in late 2008. The method compromises between easy look ahead and low move count (slice metric), and the result is 'decent' for both parts.

Steps:

  1. Columns:
    1. Solve 4 CE pairs using intuition.
    2. CMSLL (42 algs), something between 2x2 CLL and CMLL (see CxLL).
  2. Slices:
    1. Solve centres and the RD, LD and BD edges using intuition (3x centre/edge pairs actually).
    2. L5E, last five edges, solve the FD edge and the LL edges in two short alg steps.
      1. L5EO, orientation (5 algs minumum but here you can add more to force easier permutations).
      2. L5EP, permutation (16 algs).

Starting the solve

As most cubers I start from the same side/colour most times but if there is one (or more) pair compleated in the opposite colour from the scramble, then I use that side. When doing so I only solve columns opposite. These are bi-directional so you just need to turn the cube up-side-down before the slices are solved and you can go in your normal colour from there.

Inspection, this is the key to success, practice inspection to be able to predict the turns for solving 2-3 pairs and you will have good times.

Looking for the pieces for the pairs while going is the slowest part of this method so it really pays to be good at predicting the turns. Use what you got, in some scrambles two corners are solved next to each other, pair the edges on the opposite side and then put the corners there using D2 (or use a solver to find algs to put them in directly from some easy to set up to positions).

Pairs:

The move count is dependendant on how well the first step is solved, if you add some extra look ahead and pair up more than one pair before you start to place them you can get as low as 10 turns for all four pairs at times. Going like so it is even possible to solve in under 45 moves on average but not while speeding, the number of moves is not that important, the gripping while solving the pairs is the part where you can gain speed in this step, rather place a pair using U Rw U R' than (y') R' U R, that to avoid cube orientations. If you are speeding 15-17 turns is not uncommon, rather normal.

Pairing up is done a bit diffrent from what is used in Fridrich F2L, first find a pair, preferably one where the corner is unoriented in the U-layer and the edge is in the D-layer. If the edge is not there, then one in the U-layer is a second choise because it is easy to place in D using a single slice move. Orient the cube so that the edge is in FD or BD position, move the corner to position using a U move and then the pair is built using the M-slice. For the pairs where the corner or the edge is in bad position you have to do some setup turns to fix that, or simply use the CFOP alg for the same pair.

Example:

Scramble:

1.

L2 B F U2 F' L2 B' D F' U2 R D2 L F2 L' D' B2 F U2

Scramble 01.jpg
  • p1; pieces are good, just do M2 to pair up and (z) to place.
  • p2; because only one pair is solved here we can do the next from bottom and up, like this: U L2 to pair and R' U (x) to place it.
  • p3; nice corner, edge in U-layer so setup that one first using (y) M' then U M2 to pair up and U2 B' to place it (temporarly move the B-side to U before the B turn).
  • p4; both pieces in position so: (y) U2 M2 to pair up and U R' U2 R to place.

16 moves not counting puzzle rotations, pretty normal.

At bottom of this page you can find some more examples.

CMSLL:

CMSLL is pretty much the same as CLL for 2x2x2 (or CF) but in some cases you need to use double layer turns to preserve the pairs, for example R U' R' U' F' U F becomes R U' Rw' U' F' U F. In cases where that does not work any alg optimal for CMLL will do fine but with the advantage that you don't have to AUF the case so it fits with the empty M-slice, here the S-slice is equally good to use.

Algs and all cases you can find at the CxLL pages.

Example:

If we continue from the example for the pairs, then this case is Sune :P

  • (y2) R U R' U R U2 R'

Slices:

The first part of the second half of the solve is all intuitive, you pair one first layer edge with it's centre and then place it into position. After some parctice this is so easy you can say it is at noob level, no thinking required. It is possible to create more advanced methods than this and use algs for some parts but that is not a good idea, it would only kill the easiness and speed for this part of the solve.

Example:

(Continued from above)

  • p1; U' M' to pair (y) M' to place.
  • p2; paired! M' U2 M to place.
  • p3; paired again, (y') U2 M' to place.

Note that you may solve the third pair before the second using only one move, that would save one U2 but add two puzzle rotations ((y') p2 (y) p3 (y') L5EO). I usally solve the edge opposite to the first as the second one just to save on rotations, I think that it is faster on average, aspecially if you look for that edge while solving the first one. If it is stuck in D then try to find one edge that goes to the side in U instead. Then the same thing applys; solve the edge opposite to the second as the third to save on rotations.

L5E: (dunno what name I used at first but it will be L5E from here, that to stick to cubing vocabulary standards =)

Example:

(Continued from above)

  • L5EO; U' M' U' M U M' U' M to orient and place FD edge.
  • L5EP; U-PLL

See L5E for description and algs.

You only need five algs for orientation but it is a good idea to add as many as possible that also solves the FD edge, this has two reasons, first is that EPLL is faster to recognise than the full L5E permutations (the 5-cycles are particulary slow), the second reason is that EPLL skips 1:12 times, for five oriented edges that number is 1:60.

External links

More examples:

Scramble:

2.

L D2 L' D2 L F2 D2 B2 U L' F' L' R F D2 R2 U2 B2 L

Scramble 02.jpg

Inspection: One pair (orange/blue) is doable using a single M' but we like to find some more to do before we start. If we think we solve that first pair and also reorient using (z'), then the orange/green is in fine position, it needs a U' and a M to be paired and is then easily placed. Now inspection time is running out so we are pleased with that...

  • p1; M' (z') as planned.
  • p2; U' M as planned, then U2 L' U (x') to place.
  • p3; then we find a red/green corner in front of the eye and the edge is right under it so U' M' to pair up and Rw U R' to place.
  • p4; this last pair is looking bad but is not that hard, first orient the cube (y) and then R U' M2 to pair up and U R' to place.

16 STM again, as said, it's the normal.

CLL is mirror diagonal Sune, I'm using the usual Sune + inserts for this one (it is a COLL, it preserves edges orientation so if you are advanced you can look for edges to solve in the next comming step while executing the alg).

  • L' U' L U' (R U') L' (U R') U2 L inserts in parentesis.

Slices:

  • p1; M' to pair and then reorient before placement (y) U2 M'
  • p2; the opposite to the first is stuck in D so next will be orange; (y) U M' U' M.
  • p3; bad, but; (y') M' (y') M' U M (y) M the last turn will go back up again in orientation but trying to see that while going does not work well.

Last five edges:

  • L5EO; M' U M U2 M' U' M orients edges and permutes the FD edge.
  • L5EP; H-PLL