I have implemented it based on his description. I am not yet completely
satisfied, but can give some results. Both are the best I found after a
run of about 30 minutes. (The numbers are first the number of moves to
get at [F^2,R^2,B^2,L^2,U,D], second the numbr of moves to complete.)

Superflip:
(11+10=21): F B R U^2 B^2 U' D' R^2 B' R L U F^2 L^2 D^2 B^2 D' F^2 D L^2 D

Supertwist:
(7+9=16): F R^2 L^2 U^2 D^2 F^2 B' R^2 U F^2 B^2 R^2 L^2 U^2 D' L^2

So clearly the supertwist is not even close to the opposite of start!

Currently the program needs still a bit of hand-tuning. I am looking how
I can improve that.

dik
--
dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland
dik@cwi.nl