 In this case, \(B\) is a function that maps every individual \(x\) to the proposition \(\{w: x\) called in \(w\}\), and \(R\) is the set of students. In the case of a polar question, \(R\) is taken to be a set consisting of two functions on propositions, the identity function and the function that maps every proposition to its complement, which are assumed to be expressed by yes and no, respectively. For instance: