On Mar 23, 2009, at 3:34 PM, David L. Willson wrote:
Every ray must be perpendicular to every other ray. Clarifiers, if needed:- "A ray is not considered perpendicular to itself, so a koan with only one pyramid cannot have the BN." - "Rays pointing in opposite directions are parallel, not perpendicular, no matter whether the rays touch the opposing pyramid or not."
I don't understand what this means, even with the "clarifiers."