First problem
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1. P-->(G-->T) Premise
2. Q-->(T-->E) Premise
3. P Premise
4. Q Premise
// show G-->E
5. G-->T 3,1 Modus Ponens (MP)
6. T-->E 4,2 MP
7. G-->E 5,6 Hypothetical Syllogism (HS)
*** done ***
Second problem (Learn from the other two solutions, and you should
be able to easily fill in steps 4 and 5).
-----------------------------------------
1. ~S-->D Premise
2. ~Sv(~D-->K) Premise
3. ~D Premise
// show K
4. 3,1 Modus Tollens (MT)
5. 4,2 Disjunctive Syllogism (DS)
6. K 3,5 Modus Ponens (MP)
*** done ***
Third problem
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1. N-->(J-->P) Premise
2. (J-->P)-->(N-->J) Premise
3. N Premise
// show P
4. J-->P 3,1 Modus Ponens (MP)
5. N-->J 4,2 MP
6. J 3,5 MP
7. P 6,4 MP
*** done ***
If you have questions, send via the 'thank you' form.