Infinity symbol in bookbinding to indicate that a book is printed on acid-free paper and will therefore be long-lasting. In modern mysticism, the infinity symbol has become identified with a variation of the ouroboros, an ancient image of a snake eating its own tail that has also come to symbolize the infinite, and the ouroboros is sometimes drawn in figure-eight form to reflect this identification, rather than in its more traditional circular form. In the works of Vladimir Nabokov, including "The Gift" and "Pale Fire", the figure-eight shape is used symbolically to refer to the Möbius strip and the infinite, for instance
Gear Cube Pyraminx, or even the Gear Cube. They are most likely using "Singmaster notation", originally developed by David Singmaster. It allows for algorithms to be written in a way that a solver can use it no matter what side of the cube they are on. When a prime symbol ( ' ) follows a letter it indicates that move must be rotated in a counter-clockwise fashion. However, if the prime symbol is absent after the letter, that move must be rotated in a clock-wise fashion. For example: R - rotate the right side clockwise. R' - rotate the right side counter-clockwise.