 That is: Suppose \(\mathcal{O}\) is a set of options, \(\mathcal{W}\) is the set of possible worlds, and \(\mathfrak{U}\) is a disutility function. Then, if \(o^*\) is an option, and if there is another option \(o'\) such that \(\mathfrak{U}(o', w) &lt; \mathfrak{U}(o^*, w)\) for all worlds \(w\) in \(\mathcal{W}\), then \(o^*\) is irrational. (In this situation, we say that \(o^*\) \(\mathfrak{U}\)-dominates \(o'\).)