Hypothetical Syllogism/Formulation 1/Proof 1

Theorem

 * $p \implies q, q \implies r \vdash p \implies r$

Proof

 * align="right" | 6 ||
 * align="right" | 1, 2
 * $p \implies r$
 * $\implies \mathcal I$
 * 3, 5
 * 3, 5