Posted: March 2nd, 2017

Construct a formal proof for each of these arguments.

For each of the following arguments, adding just two statements to the premises will produce a formal proof of its validity. Construct a formal proof for each of these arguments.

1. W ⊃ X

2. Y ⊃ X

Therefore, W ⊃ Y

9.9 exercise 2

Prove the invalidity of the following by the method of assigning truth values.

Not (E and F)

(not-E and not-F) implies (G and H)

H implies G

Therefore, G

9.10 A Exercise 2

For the following, either construct a formal proof of validity or prove invalidity by the method of assigning truth values to the simple statements involved.

(E implies F) and (G implies H)

Therefore, (E or G) implies (F and H)

9.11, argument 3 —- in page 394.

For each of the following arguments, construct an indirect proof of validity.

1. (D v E) ⊃ (F ⊃ G)

2. ( G v H) ⊃ (D · F)

Therefore, G.