Proposition 74: Reflexivity of implication (inference rule)

We may (from no premises at all) infer that the implication \phi \Rightarrow \phi holds: \cfrac{}{\vdash (\phi \Rightarrow \phi)}.

Proof: By the identity rule, \phi entails \phi . By conditional introduction, we infer that \phi \Rightarrow \phi holds. \square