 Intuitionistic propositional logic \(\mathbf{H–IPC}\) is the subsystem of \(\mathbf{H–IQC}\) which results when the language is restricted to formulas built from proposition letters \(P, Q, R,\ldots\) using the propositional connectives \(\oldand, \vee , \rightarrow\) and \(\neg,\) and only the propositional postulates are used. Thus the last two rules of inference and the last two axiom schemas are absent from the propositional subsystem. 