jerry asks

A 24q process is known for superflip. It is known that superflip is
greater than 19f. Is a 20f process known for superflip?

on may 17, 1992, dik winter gave

) Superflip:
) (13+7=20): F B U^2 R F^2 R^2 B^2 U' D F U^2 R' L' U B^2 D R^2 U B^2 U

in my exhaustive search for superflip maneuvers of length <= 19f,
several (but not all) branches of my search found maneuvers of length 20f.
all were equivalent to dik's under the three operations

* conjugation of the sequence by a symmetry of the cube
* cyclic permutation of the sequence
* inversion of the sequence

perhaps it is the case that dik's maneuver is "unique" up to these
operations.

mike