In einer eMail vom 12.07.2008 21:04:28 Westeuropäische Normalzeit schreibt
bill@herrin.us:
Would you like to redraw your red arrows? Can you think of a Well, it requires a red arrow not only from B to C but also from C to
B.
But then all black lines are replaced by pairs of oppositely directed
arrows.
So we have no restricted situation anymore.
Heiner, shruging my shoulders
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