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Fri 29 Apr, 2016 12:30 pm
I have no idea how to solve this logic proof, please help!
(1)(I&E)>~F
(2)Fv(G&H)
(3)I=E /(conclusion) I>G
Any help would be greatly appreciated! (Key: "&"= and, ">"= if_then_, "~"= not, "v"= or, "="= if and only if
@kludewig,
method of BACKWARD FELL SWOOP
The only values which make the conclusion false, are I is true and G is false. Put those into the conjunction of the premises and show that that conjunction turns out to be false using those values. This would prove the argument valid since only a conjunction of false premises gives a false conclusion. Conversely if the conjunction of premises was true using those values for the conclusion to be false, the argument would be invalid.
@kludewig,
Note that if you do that, premise 2 will be false, making the conjunction of 1 & 2 & 3 false.
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