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Tue 2 Dec, 2014 04:57 pm
Hello i need help solving this proof i keep going in cicrles trying to figure it out
1. ~C ⊃ ~D
2. (~C ⊃ ~E) ⊃ ~A
3.~D ⊃ ~E / ~A
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@rsauce1,
rsauce1 wrote:
Hello i need help solving this proof i keep going in cicrles trying to figure it out
1. ~C ⊃ ~D
2. (~C ⊃ ~E) ⊃ ~A
3.~D ⊃ ~E / ~A
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So you're trying to prove ~A?
Here's my proof using
http://en.wikipedia.org/wiki/List_of_rules_of_inference#Table:_Rules_of_Inference
1. ~C ⊃ ~D [given]
2. (~C ⊃ ~E) ⊃ ~A [given]
3.~D ⊃ ~E [given]
4. ~C ⊃ ~E [by 1, 3, and "hypothetical syllogism"]
5. ~A [by 2, 4, and "modus ponens"]
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