Errata

We thank Carlos Cinelli and Tomás Varnet Pérez for bringing the following typos to our attention. 

Example 4: Positions of X and Y should be swapped in both G1 and G2. So, G1: X-->Y-->Rx-->Ry and G2: X-->Y-->Rx<--Ry.

Figure 8: captions of (a) and (d) should be swapped. 

Last Updated: 18 Nov 2024