 Definition 1 (Curry sentence) Let \(\pi\) be a sentence of the language of \(\mathcal{T}\). A Curry sentence for \(\pi\) and \(\mathcal{T}\) is any sentence \(\kappa\) such that \(\kappa\) and \(\kappa {\rightarrow}\pi\) are intersubstitutable according to  \(\mathcal{T}\).[4]