Self-Distributive Law for Conditional/Forward Implication/Formulation 2/Proof 1

Theorem

 * $\vdash \left({p \implies \left({q \implies r}\right)}\right) \implies \left({\left({p \implies q}\right) \implies \left({p \implies r}\right)}\right)$

Proof
By the tableau method of natural deduction: