Exportation and Self-Conditional
From ProofWiki
Theorem
- $p \land q \implies r \dashv \vdash \left({p \implies q}\right) \implies \left({p \implies r}\right)$
Proof
From the Rule of Exportation:
- $\left ({p \land q}\right) \implies r \dashv \vdash p \implies \left ({q \implies r}\right)$
Then by Self-Distributive Law for Conditional:
- $p \implies \left({q \implies r}\right) \dashv \vdash \left({p \implies q}\right) \implies \left({p \implies r}\right)$
$\blacksquare$