INTERMEDIATE LOGC


Problems 1- 5: using the rules of inference or replacement already supplied, fill in each step of the proof. Write QED when finished.


1)

T ⊃ P 1
D ⊃ P 2
T v D / .’. P
(T ⊃ P) • (D ⊃ P)
P v P
P




2)

S ⊃ G
∼ S ⊃ P / .’. G v P
∼ G ⊃ ∼ S
∼ G ⊃ P
∼ ∼ G v P
G v P













3)

∼ G ⊃ (L v I)
∼ L
I / .’. G
∼ L v ∼ I
∼ (L • I)
∼ (I • L)
∼ I
∼ L • ∼ I
∼ (L v I)
∼ ∼ G
G



4)
P .’. / ∼ P ⊃ Q
P v Q
∼ [∼ P] v Q
∼ P ⊃ Q


5)
A ⊃ B
B ⊃ C
∼ C .’. / ∼ A
A ⊃ C
∼ A