A function

When evaluated,

Properties

1 & \text{ if } \tau^(p_1) = 0 \text{ or } \tau^{}(p_{2}) = 1\ 0 & \text{ otherwise } \end{cases}$$

1 & \text{ if } \tau^(p_1) = \tau^{}(p_{2})\ 0 & \text{ otherwise } \end{cases}$$