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      1 <!--TITLE: Rubik's cube notation-->
      2 <h1>Rubik's cube notation</h1>
      3 
      4 <p>
      5 This page describes the classic
      6 <a href="https://www.speedsolving.com/wiki/index.php/Singmaster_notation">
      7 Singmaster notation</a> for the Rubik's cube, with some commonly used additions.
      8 </p>
      9 
     10 <h2>Basic moves</h2>
     11 
     12 <p>
     13 Each of the six faces of the cube is assigned a letter:
     14 </p>
     15 
     16 <table>
     17 <tr><td><strong>U</strong></td><td>Upper face</td></tr>
     18 <tr><td><strong>D</strong></td><td>Down face</td></tr>
     19 <tr><td><strong>R</strong></td><td>Right face</td></tr>
     20 <tr><td><strong>L</strong></td><td>Left face</td></tr>
     21 <tr><td><strong>F</strong></td><td>Front face</td></tr>
     22 <tr><td><strong>B</strong></td><td>Back face</td></tr>
     23 </table>
     24 
     25 <p>
     26 A single letter (like U) denotes a 90° turn <em>clockwise</em>, a
     27 letter followed by a single quote (like U') denotes a 90° turn
     28 <em>counter-clockwise</em>, and a letter followed by a 2 (like U2) denotes a
     29 180° turn.
     30 </p>
     31 
     32 <p>
     33 Basic moves are summarized in the following table (<strong>white face on
     34 top</strong> and <strong>green face on front</strong>):
     35 </p>
     36 
     37 <table>
     38 <tr>
     39 <td><div style="text-align: center"><img src="u.png"><strong>U</strong></div></td>
     40 <td><div style="text-align: center"><img src="u3.png"><strong>U'</strong></div></td>
     41 <td><div style="text-align: center"><img src="u2.png"><strong>U2</strong></div></td>
     42 </tr>
     43 <tr>
     44 <td><div style="text-align: center"><img src="d.png"><strong>D</strong></div></td>
     45 <td><div style="text-align: center"><img src="d3.png"><strong>D'</strong></div></td>
     46 <td><div style="text-align: center"><img src="d2.png"><strong>D2</strong></div></td>
     47 </tr>
     48 <tr>
     49 <td><div style="text-align: center"><img src="r.png"><strong>R</strong></div></td>
     50 <td><div style="text-align: center"><img src="r3.png"><strong>R'</strong></div></td>
     51 <td><div style="text-align: center"><img src="r2.png"><strong>R2</strong></div></td>
     52 </tr>
     53 <tr>
     54 <td><div style="text-align: center"><img src="l.png"><strong>L</strong></div></td>
     55 <td><div style="text-align: center"><img src="l3.png"><strong>L'</strong></div></td>
     56 <td><div style="text-align: center"><img src="l2.png"><strong>L2</strong></div></td>
     57 </tr>
     58 <tr>
     59 <td><div style="text-align: center"><img src="f.png"><strong>F</strong></div></td>
     60 <td><div style="text-align: center"><img src="f3.png"><strong>F'</strong></div></td>
     61 <td><div style="text-align: center"><img src="f2.png"><strong>F2</strong></div></td>
     62 </tr>
     63 <tr>
     64 <td><div style="text-align: center"><img src="b.png"><strong>B</strong></div></td>
     65 <td><div style="text-align: center"><img src="b3.png"><strong>B'</strong></div></td>
     66 <td><div style="text-align: center"><img src="b2.png"><strong>B2</strong></div></td>
     67 </tr>
     68 </table>
     69 
     70 <p>
     71 <strong>Note:</strong> "clockwise" or "counter-clockwise" is always
     72 intended when <em>looking at the face you are turning</em>. This is
     73 why from the pictures above it looks like, for example, U and D go in
     74 opposite directions.
     75 </p>
     76 <p>
     77 If this sounds confusing, think about it: if you put a clock face down
     78 on the table, does it turn clockwise or counter-clockwise?
     79 </p>
     80 
     81 <h2>Full-cube rotations</h2>
     82 
     83 <p>
     84 Sometimes it is convenient to start a move sequence with the cube in a
     85 different orientation. To denote this, it is common to use the "moves"
     86 x, y and z that denote a full-cube rotation:
     87 </p>
     88 
     89 <table>
     90 <tr><td><strong>x</strong></td><td>Follows R</td></tr>
     91 <tr><td><strong>y</strong></td><td>Follows U</td></tr>
     92 <tr><td><strong>z</strong></td><td>Follows F</td></tr>
     93 </table>
     94 
     95 <p>
     96 The same modifiers can be applied, so for example x2 is a full-cube
     97 rotation that follows R2 (or, equivalently, L2) and z' is a a
     98 full-cube rotation that follows F' (or, equivalently, B).
     99 </p>
    100 
    101 <h2>Inner-layer moves</h2>
    102 
    103 <p>
    104 Moving two parallel layers of the cube, one clockwise and one
    105 counter-clockwise, has the same effect as moving the inner layer
    106 between them. We usually denote these inner-layer moves by
    107 M, E and S.
    108 </p>
    109 
    110 <table>
    111 <tr><td><strong>M</strong></td><td>Follows L</td></tr>
    112 <tr><td><strong>E</strong></td><td>Follows D</td></tr>
    113 <tr><td><strong>S</strong></td><td>Follows F</td></tr>
    114 </table>
    115 
    116 Or in pictures:
    117 
    118 <table>
    119 <tr>
    120 <td><div style="text-align: center"><img src="m.png"><strong>M</strong></div></td>
    121 <td><div style="text-align: center"><img src="e.png"><strong>E</strong></div></td>
    122 <td><div style="text-align: center"><img src="s.png"><strong>S</strong></div></td>
    123 </tr>
    124 </table>
    125 
    126 <p>
    127 The same modifiers can be applied, so for example M2 means moving the inner
    128 layer between R and L by 180°.
    129 </p>
    130 
    131 <p>
    132 <strong>Note 1:</strong> unfortunately, the notation for inner-layer moves
    133 is not consistent with that for full-cube rotations. For example x follows R
    134 but M follows L.
    135 </p>
    136 
    137 <p>
    138 <strong>Note 2:</strong> Inner-layer moves can always be rewritten as a
    139 combination of basic moves and full-cube rotations. For example, M'
    140 is equivalent to x R' L.
    141 </p>