Help with a natural deduction proof

Question

Does anyone have any idea how to prove this?

/[P ⊃ (Q ⊃ R)] ⊃ [(P ⊃ Q) ⊃ (P ⊃ R)]

So far I have

1' P ⊃ (Q ⊃ R)         AcP

 2' P ⊃ Q              AcP

  3' ~P                AIP

Thanks

Answer 1

Standard notation is "$\to$" for "implies" because "$\supset$" denotes "[strict] superset". Also, "$\neg$" is standard for "not".

If $P \to ( Q \to R )$:

  If $P \to Q$:

    If $P$:

      $Q \to R$.

      $Q$.

      $R$.

$\cdots$

I'll leave you to fill in the final steps and the justification for each step.