 Frege also supposed that when a binary function \(f\) (i.e., a function of two arguments) always maps the arguments \(x\) and \(y\) to a truth value, \(f\) is a relation. So it should be remembered that when we use the expression ‘\(Rxy\)’ (or sometimes ‘\(R(x,y)\)’) to assert that the objects \(x\) and \(y\) stand in the relation \(R\), Frege would say that \(R\) maps the pair of objects \(x\) and \(y\) (in that order) to The True. But again, this Fregean interpretation is not required for understanding Frege’s Theorem. In what follows, we shall sometimes write the symbol that denotes a mathematical relation in the usual ‘infix’ notation; for example, ‘\(\gt\)’ denotes the greater-than relation in the expression ‘\(x \gt y\)’.