Rubik's cube

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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 (r' R), Equator (u' U), 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.

Acronyms:

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:

S Sexy move R U R' U'
Sp Sexy move prime U R U' R'
SL sledgehammer R' F R F' F' with right thumb!
SLp sledgehammer prime F R' F' R
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

From https://www.youtube.com/watch?v=WXSs2wRC7KE: 

 1 R U R' U'
 2 U R U' R'
 3 L' U' L U
 4 U' L' U L
 5 R' F R F'
 6 R' U R U'
 7 L F' L' F
 8 L U' Lu U
 9 R U2 R'
10 R U R' U
11 R U' R' U'
12 R' U' R U'
  • Andy Klise classifies triggers in three colors [2], 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)

Tutorials

F2L

See Rubik F2L.

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

Fridrich - OLL

TBC

Fridrich - PLL

Source: http://www.cubewhiz.com/pll.php 

Cycling Three Corners & Three Edges - Detecting Ga, Gb, Gc, Gd perm

- Put the good corner & edge at its position
- Turn the cube such that to have the "head lights" (the corners with same side color) on the L face
- Ga: good corner on F face
  Gb: good corner on R/back face
  Gc: good corner on B face
  Gd: good corner on R/front face

  Ga: (R2' Uw) (R' U R' U' R Uw') R2' y' (R' U R)      R2 R' R' R                      Uw U U' Uw'
  Gb: (R' U' R) y (R2' Uw R' U) (R U' R Uw' R2')       R2 R' R  R                      Uw U U' Uw'
  Gc: (R2' Uw' R U') (R U R' Uw R2) (Fw R' Fw')        right thumb U face R2' R R R'   Uw' U' U Uw
  Gd: (R U R') y' (R2' Uw' R U') (R' U R' Uw R2)       R2' R R' R'                     Uw' U' U Uw
Ja permutation
Ja
  • z (D' R U') R2 (D R' D') R2 (U D R')
Na / Nb permutations
Na
  • z U _(R' D)_ (R2 U' R U D') _(R' D)_ (R2 U' R D' [R])
  • Use normal grip after z
  • RH sexy regrip during the first and second U'
  • Last R assumes following start position (X means cube at correct position)
       (B)
      . . X
(L)   X X X    (R)
      X . .  
       (F)
  • After z U face must have the following pattern:
X X .
X X X
X X X
Nb
  • z U' (R D') (R2 U R' D U') (R D') R2 U R' D [R]
  • Use normal LH grip, RH sexy grip after z
  • RH sexy regrip for both R2. All U, D' done with RH.
  • Last R assumes following start position (X means cube at correct position)
       (B)
      . X X
(L)   . X .    (R)
      X X .  
       (F)
  • After z U face must have the following pattern:
X X .
X X .
X X X

Algorithms

PLL - swap 2 edges
  • R U R' U R U2 R' U

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.

My progress

Short-term plan
  • Use fast solve U2 R' F R F' U2 R U R' for F2L #24.
  • 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
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