 Similarly for an \(n+1\) place relation for each \(x_1\), …, \(x_n\) there is a unique y such that \(R(x_1, \ldots, x_n, y)\), then one can introduce an n-place function g mapping \(x_1, \ldots, x_n\) onto y. In PM the expressions for mathematical functions are definite descriptions, referring to the last argument of a relation as the “value” of the function described by that relation. We will use the expression \(f_R\) to refer to the functional term referring to the function derived from a relation R. PM uses the explicit definite description “the R of y” (written \( R`y \) ) where we would use the functional expression \(f_R\). The definition of a monadic functional term then is: