 In applications of free logic involving partial functions, the existence predicate ‘\(\rE!\)’ is often replaced by the postfix definedness predicate ‘\(\downarrow\)’. For any singular term \(t, t\downarrow\) is true if and only if \(t\) has some definite value in \(\bD\). Thus, for example, the formula ‘\((1/0)\downarrow\)’ is false. While some writers (e.g., Feferman (1995)) distinguish ‘\(\downarrow\)’ from ‘\(\rE!\)’, the literature as a whole does not, and ‘\(\downarrow\)’ is often merely a syntactic variant of ‘\(\rE!\)’.