\(\tilde \tau _{1}={\left (\tau _{1}, s_{1}\right)}\) | \(\tilde \tau _{2} = \left ({ \tau _{1},s_{2}}\right)\) | \(\tilde \tau _{3} = \left ({ \tau _{2}, s_{1}}\right)\) | \(\tilde \tau _{4} = \left ({ \tau _{2},s_{2}}\right)\) | |
---|---|---|---|---|

z
_{1}
| × | ✓ | × | ✓ |

z
_{2}
| ✓ | × | ✓ | × |

z
_{3}
| × | ✓ | × | ✓ |

z
_{4}
| ✓ | × | ✓ | × |