This is a real-neat program, BUT:

In solving the cube, the description it gives for the action it is
about to perform can be ambiguous, I think. For example, can't "Turn
TOP center to BOTTOM" be performed in two non-equivalent ways?

I don't know what the display format is on color LISP machines, but on
my terminal is sucks. How about something like this:

		+--------+
	       / YL YL YL \
	      /		   \
	     /  YL  YL  YL  \
	    /		     \
	   /   YL   YL	 YL   \
	 ,-+------------------+-.
      ,-'  |		      |  `-.
   ,-'  GR |   RD   RD	 RD   | BL  `-.
+-'  GR    |		      |    BL  `-+----------+
| GR	   |		      |       BL | OR OR OR |
|	   |		      |		 |	    |
| GR GR GR |   RD   RD	 RD   | BL BL BL | OR OR OR |
|	   |		      |		 |	    |
| GR	   |		      |       BL | OR OR OR |
+-.  GR    |		      |    BL  ,-+----------+
   `-.  GR |   RD   RD	 RD   | BL  ,-'
      `-.  |		      |  ,-'
	 `-+------------------+-'
	   \   WH   WH	 WH   /
	    \		     /
	     \  WH  WH  WH  /
	      \		   /
	       \ WH WH WH /
		+--------+

Maybe add FRONT, BACK, LEFT, RIGHT, TOP, BOTTOM labels; maybe compress
it vertically so it fits on 24-line screens; maybe three-char abbrevs
instead of two; maybe the back face should be shown reversed (i.e.
from the inside of the cube looking out) to facilitate mental
manipulations; the basic format is better, though, don't you agree?

---
Jef