Symmetry in the case of tie knots can refer to two possible qualities: "visual" symmetry (the extent to which the knot appears to be shaped identically on the left and right side), and "mathematical" symmetry (the number of L and R moves being as close to equal as possible). Fink and Mao refer to the latter, even though some knots that are slightly asymmetrical (such as the Nicky and the Windsor) appear symmetrical to the eye. Only knots with an equal number of total L and R moves can be mathematically symmetrical, while the remainder of the aesthetic knots will necessarily have one greater L or R move.