A Concise Introduction to Logic, Patrick J. Hurley, Wadsworth, 2006, 9th ed,. 7.7, 14, p. 390

 Prove the logical truth.

1.     (P ⊃ Q) ⊃ R 2.     R ⊃ ~ R 3.     ~ R v ~ R 4.     ~ R 5.     ~ (P ⊃ Q) 6.     ~ (~ P v Q) 7.     P • ~ Q 8.     P 9.     (R ⊃ ~ R) ⊃ P 10.  [(P ⊃ Q) ⊃ R] ⊃ [(R ⊃ ~ R) ⊃ P]

/ [(P ⊃ Q) ⊃ R] ⊃ [(R ⊃ ~ R) ⊃ P] ACP ACP 2 Impl 3 Taut 1,4 MT 5 Impl 6 DM 7 Simp 2-8 CP 1-9 CP