Proofs II, #11
derive ~S
1. | (F & ~G) v (T & ~W) | premise | |
2. | (W & H) | premise | |
3. | ~(F ⊃ G) ⊃ (H ⊃ ~S) | premise | |
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Strategy |
Get ~(F
⊃
G) which is ~(~F v G) which is (F & ~G) so get (F & ~G) by getting ~(T & ~W) which is (~T v ~~W) or (~T v W) But we have (W & H) and so we have W and so ~T v W by disjoining.
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