                        SINGMASTER'S NOTATION

The six faces of the cube, in any fixed orientation, can be named
Right, Left, Front, Back, Up, and Down, and  are abbreviated by their
initial letters R,L,F,B,U,D.  Pairs of letters can used to identify an
edge (e.g. UF), and triplets to identify a corner (e.g. URF), the
three faces preferably being described in clockwise order when viewed
from outside the cube. The six letters R,L,etc., are also used to
define 90 clockwise turns of the faces of the cube; thus F indicates
a clockwise turn of the face F nearest the viewer, the middle slice
and the B face being unaffected.  The same letters followed by an
apostrophe are used to specify a 90 counter-clockwise rotation; thus
R' denotes a 90 counter-clockwise turn of R as viewed when looking at
R from outside the cube.  In any substage, the orientation of the cube
should not be altered (except temporarily, to inspect the three hidden
faces). Twelve of the ikons in the computer display are marked as
indicated above, thus facilitating documentation, etc., of moves.

R, (RU)U'BF' respectively mean RR and RRUURRUURRUUU'BF', etc.

For example, with the cube in the start position, (RFL)  gives the
"pretty pattern" of file FourBar in the CubeFiles directory.

For any set of instructions, the individual moves
(R,L,...,R',L',...,etc.) are executed from left to right, and the
orientation of the cube should not be altered except temporarily; e.g.
if, at the start, the centre square of F is blue and the centre square
of R is red, these conditions should be maintained. 

This notation is due to Professor David Singmaster, whose pamphlet
"Notes on Rubik's Magic Cube" (IBSN-89400-043-9, published by the
author at the Department of Mathematical Sciences and Computing,
Polytechnic of the South Bank, London, SE1 0AA), gives a step-by-step
solution of Rubik's cube using his notation, together with much
fascinating information.



 