Mike Nelson wrote on Fri, Nov 1, 2002 12:14 AM UTC:
Peter,
You are quite correct, this is both the best way to phrase the rule and to
implement it in software. It has eactly the same effect as Craig's rule
and my rephrasing of it. We are, however, not in disagreement about the
originality of the concept--in my original comment, I stipulated 'with one
royal piece'.