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willemk is offline
Jan14-07, 09:08 PM
P: 1
1. The problem statement, all variables and given/known data

I don't have symbols for negations, so i'll just use the word NOT..

Prove the validity of the sequents below:

NOT ( P -> Q) YIELDS Q-> P

2. Relevant equations

Relavent deductions as listed here..

Using things such as ^ elimination/introduction, Modens Ponens,.. etc

3. The attempt at a solution

1. NOT ( P -> Q) Premise
2. NOT Q Assumption
3. NOT NOT P MT 1,2 (added in extra negation from line 1)
4. P NOT NOT Elimination
5. NOT Q -> P

I"m looking for Q -> P.. which the opposite answer.. i think its something to do with the negations being all wrong.. any help??
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