Hello everybody, I just realized that I was talking nonsense a week ago, claiming the projective metric would be given by $$\cosh d_{pr} (P,Q) = \frac{1}{2} \ln \cr(Q,X,P,Y)$$. The correct formula is $$d_{pr} (P,Q) = \frac{1}{2} \ln \cr(Q,X,P,Y)$$. I hope … Continue reading Tutorials 9./10. 1.