Re: Oh my God!

An addendum to my previous post:
I only discussed HALF of the necessary analysis.  In order to prove
that a solution is consistent (i.e, a closed loop solution is found
which does not violate RoS), it must be so from the perspective of
A and B as well as from the perspective of C and D.
Your schema does so with infinite speed tachyons in both frames.
Other arrangements are not so forgiving.  Some are consistent in
one frame, but not in the other when obeying RoS.  In that case,
a closed loop is not a valid solution.  There are several examples
of this type.