mark writes

I am working on an engine to search optimal paths for < U, F, R > but
it's not done yet. It's certainly within the bounds of computibility:

Size (u_f_r) = 170,659,735,142,400 (hmmm, 170 trillion maybe not!)

it should be possible to write a good searching program for this
subgroup. use the filtration

<U, F, R> ,  <U, F2, R2> ,  <>

(which is just the last two stages of the three stage filtration i
gave on may 22, 1992), and a kociemba-type searching method.
i don't know if it will be feasible to find optimal paths, but
this technique should get pretty close.

let us know what you find out!

mike