Date:     19 July 1980 1524-edt
From:     Bernard S. Greenberg	 <Greenberg at MIT-Multics>

... I am not convinced that there is any
better or faster check for an inconsistent/unreachable
cube than trying to solve it and blowing out: ...

You mean I haven't convinced you of that yet? Show me how your cube
is represented and I will write one for you. What would be so bad
about blowing out anyway? What happens when you hand a person an
impossible cube? his algorithm "blows out" eventually! There is no
shame in being tricked into trying to solve a bad cube.