Aha, so you and Dirk don't know what symmetrical transformation is. Thanks
for showing that to both of you.

Lorentz transformation

  x' = (x - vt) / sqrt(1 - v^2/oc^2)
  t' = (t - vx/c^2) / sqrt(1 - v^2/oc^2)

are symmetrical in the sense that x' and x, and t and t' can switch the
places, while speed v changes the sign. This is symmetrical transformation

  x = (x' + vt') / sqrt(1 - v^2/oc^2)
  t = (t' + vx'/c^2) / sqrt(1 - v^2/oc^2)

They give two solutions for the same events, thus the premise of invariance
of the speed of light is incorrect, or the premise of the relativity of
motion. Either must be rejected, or both. This is the proof of invalidity in
general case, which I presented.

Aleksandar