Question 3
select the correct proof of validity for |- (p^q) ? p
?
1. (p^q)
2. p
3. (p^q) ? p
premise
?e? 1
-> i 1-2
?
1. (p^q)
2. p
3. (p^q) ? p
given
?e? 1
-> i 1-2
?
1. (p^q)
2. p
3. (p^q) ? p
assumption
?e? 1
-> i 1-2
?
1. (p^q)
2. p
3. (p^q) ? p
assumption
?e? 1
-> i 1-2
Question 4
Prove the validity of p |- (p ? q) ? q
?
b) 1. p
2. (p ? q)
3. q
4. (p ? q) ? q
premise
given
? e 2, 1
conclusion
?
c) 1. p
2. (p ? q)
3. q
4. (p ? q) ? q
premise
assumption
Ve 2, 1
? i 2-3
?
a) 1. p
2. (p ? q)
3. q
4. (p ? q) ? q
premise
assumption
? e 2, 1
? i 2-3
?
d) 1. p
2. (p ? q)
3. q
4. (p ? q) ? q
premise
assumption
? e 2, 1
? i 2, 3