Rubik's cube

From miki
Revision as of 17:05, 9 September 2016 by Mip (talk | contribs) (→‎My progress)
Jump to navigation Jump to search

Pages on this wiki

Notations and acronyms

Official notation [1]:

F B U D L R Front, Back, Up, Down, Left, Right (one-layer move)
f b u d l r Front, Back, Up, Down, Left, Right (two-layer move, aka. wide move)
Fw Bw Uw Dw Lw Rw
M E S Middle (l L'), Equator (d D'), Standing (f F') (middle layer move, aka slice move)
x y z R, U, F (whole cube move)
  • R means 90° clockwise, R' mean 90° counter-clockwise, R2 means 180° clockwise, and R2' 180° counter-clockwise.
  • Alternative notation for easier pronunciation uses T (for Top) instead of U. This way all faces start with a consonnant. Using O for clockwise move, A for anti-clockwise, and I for 180° move, an algorithm like the sexy move becomes then RoToRaTa.

Finger tricks and grips:

Acronyms:

AUL Adjust Upper Layer — rotate up face until it is solved, or matches a desired position.
LH Left-hand
RH Right-hand

Triggers

We call a move a permutation on the cube that can be done in a single movement. This can be the rotation of a face by 90° or 180°, but also rotation of a middle layer, two layers, or the whole cube. Each move has a dedicated letter, with a prime indicating the reverse movement.

A trigger is a small squence of moves that is frequently used to build up more complete algorithms. Typically these sequences are done very rapidly. Fast algorithms are those that link several triggers with an easy transition (no re-gripping, cube rotation, etc). The inverse of a trigger is the sequence that cancel the effect of that trigger. We use prime to denote that trigger. A mirror trigger is the M-symmetric trigger (i.e. F changes to F', R changes to L', etc)

List of triggers:

1 S Sexy move R U R' U'
2 Sp Sexy move prime U R U' R'
3 LS Left sexy move L' U' L U
4 LSp Left sexy move prime U' L' U L
5 SL sledgehammer R' F R F' F' with right thumb!
SLp sledgehammer prime F R' F' R
7 LSL left sledgehammer L F' L' F Same as y' SLp y.
LSLp left sledgehammer prime F' L F L' Same as y' SL y.
O Overshoot U' R' F R
6 R' U R U'
8 L U' L U
9 Anti-sune R U2 R'
10 Sune R U R' U
11 R U' R' U'
12 R' U' R U'
  • Badmephisto (see Andy Klise [2]) classifies triggers in three colors, from the position of prime moves:
  • Red = R U R' U' family (i.e. X Y X' Y')
  • Green = R U R' U family (i.e. X Y X' Y)
  • Blue = R F' R' F family (i.e. X Y' X' Y)
  • Andy Klise's guide use a different color coding:
  • Green = R U R' U' family
  • Blue = R U R' U R U2 R' family
  • Orange = R F' R' F family

Tutorials

See Rubik F2L, Rubik OLL and Rubik PLL for dedicated tutorials.

Fridrich simplified

Source: Rubik's cube : Méthode intermédiaire (fridrich simplifiée)

4 steps:

  • Cross
  • F2L
  • 2-look OLL
  • 2-look PLL

For F2L, see tutorial above.

For 2-look OLL, first do the cross:

  • Line shape: F sexy F' (F' with the thumb)
  • L shape: f sexy f' (f' with the thumb)
  • no shape: do 1st then 2nd algorithm

Then we do one of the 7 OLL "cross" algorithms. The cases are denoted by the position of yellow sticker for each corner, starting from FL, the FR, BR and BL corner. So UFRB means the yellow sticker facing upward for the left-front corner, facing front for the right-front corner, facing right for the right-back corner, and facing back for the left-back corner.

  • UFRB: R U R' U R U2 R'
  • FRUL: R U2 R' U' R U' R' (inverse of UFRB)
  • FFUU: R2 D R' U2 R D' R' U2 R' (D and D' ideally by pulling then pushing with left-hand finger)
  • LRUU: x' R U R' D R U' R' D' (idem) (x' R → l, so l U R' D R U' R' D') (or variant UFBR: l' U' L U R U' r' F)
  • URUB: x' R U' R' D R U R' D' (idem) (x' R → l, so l U' R' D R U R' D')
  • FFBB: F sexy sexy sexy F'
  • LFBL: R U2 R2' U' R2 U' R2 U2 R

For 2-look PLL, like for the 2-OLL, we first do the cross, then the corners. For the cross, turn the U face until 1 edge is good, and place it at F slot, and look how the other edges must be permuted.

  • All edges are ok: congratulations ;-)
  • clockwise: R' U R' U' R' U' R' U R U R2' (R' U R' U' with right index under BRD corner, then R' U' R' U with right index next to FRD corner)
  • anti-clockwise: R2' U' R' U' R U R U R U' R (right thumb on B face, right index on FRD corner, ready for 1st U, then R U' R with RH, U' with right thumb)
  • 2 edge ok: do either of algorithm above, and retry.

Then look at the corners. If one corner is good, turn the cube such that it is at FL slot, and look how the other corners must be permuted

  • 1 good corner (FL), clockwise: x R' U R' D2 R U' R' D2 R2 or l' U R' D2 R U' R' D2 R2 (using x R' → l'). My old fingertrick was left thumb on F center, left index/middle/ring fingers on back, right thumb on U face, right index under RBD corner. First U done with right index, then D2 done with left ring+middle or left little+ring, then U' done with right thumb, like for the sledgehammer. This fingertrick is not adviced, instead train on using the left index to do the U' move [3].
  • 1 good corner (FL), anti-clockwise: x R2' D2 R U R' D2 R U' R l' R' D2 R U R' D2 R U' R (best grip: left thumb on D face, right thumb on F face, left ring finger to prepare the D2 / D2, right index to prepare the U.
  • no good corner: do either of algorithm above, then you will have a good corner

Algorithms

PLL - swap 2 edges
  • R U R' U R U2 R' U
Sexy moves and reverse, mixed with F face
  • f (R U R' U') f' is reversed by f (U R U' R') f' but also by U² F (R U R' U') F'. This is true for any number of sexy moves (R U R' U') we do.

Cross

  • Be color neutral.
  • Do d move to avoid cube rotation might help.

Finger Tricks

  • D2 move
Use the ring and major finger. To work well, hold the cube with index and thumb such that ring and major hits the left (or right) side of the D face almost vertically. For instance, using the left hand, the index must hold both the LBU corner and LB edge, and possibly a bit the center back face and BU edge. See this video.
  • Left sledgehammer
The left sledgehammer is L F' L' F. In the right sledgehammer, the F is done with the thumb. Here it is best to do is as r U' r' F, using the LH only for the U'. Also the r can be done by pushing with the right ring finger at the bottom of the cube to avoid the re-grip (see VC 9:55).

Look-ahread

Effect of two sexy moves ((R U R' U') (R U R' U') or (L' U' L U) (L' U' L U))
  • Corners don't move but are rotated: 3 corners on the U faces and 1 corner on the D face.
  • Edges keep their parity but moves: 2 edges on the U face and 1 edge on the F face.

My progress

Short-term plan
  • F2L: Practice and apply algo marked with TRAINME.
  • Use x-cross for F2L cases with correct edge or correct corner when faster.
Long-term plan
  • Learn OLL (57 cases)
  • Learn partial edge control to avoid dot-OLL cases.
  • Learn COLL
To Do
  • View and integrate Victor Colin's video on multi-slotting
  • View / integrate video Badmephisto on OLL resolution (+partial edge control)
  • View / integrate video Badmephisto on F2L.

Questions

If I could me an rubik expert:

  • How practice F2L look-ahead? Should we first well visualize the F2L case, how to insert it, then do it? But how do we follow the position of the side color, since we might do cube rotation? Do we have to also explicitly keep track of which slot is already filled, etc?

=== Example of cross resolution:

  • Below, an example of setup move.
Scramble:
B2 R2 L2 F2 U' B2 L2 D R2 L2 U R' B' R D2 L U' R L B' D U'

yellow top, green front:
U' L2 F' L' D B L' D
--                    Setup move for green
   --------           We set blue and orange. Now red is ready, with green to follow nicely
            ------    We set red and green.
                   -- Adjust bottom layer
Retrieved from "https://miki.immie.org/mediawiki/index.php?title=Rubik%27s_cube&oldid=8508"