 A zero comparison: Individual \(i\)’s welfare under alternative \(x\) is greater than / equal to / less than zero, formally \(\textit{sign}(W_i (x)) = \lambda\), where \(\lambda \in \{-1, 0, 1\}\) and \(\textit{sign}\) is a real-valued function that maps strictly negative numbers to \(-1\), zero to 0, and strictly positive numbers to \(+1\).