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 Post subject: Propositional Logic ProblemsPosted: Wed, 6 Oct 2010 10:56:25 UTC
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Joined: Wed, 6 Oct 2010 10:54:30 UTC
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Use propositional logic to prove that the statement is valid:

1) [A → (B → C)] ^ (A V ~D) ^ B → (D → C)
2) (A → B) ^ [B → (C → D)] ^ [A → (B → C)] → (A → D)
3) A V B, A → C, B → C → C

Hope to get some help by getting some sort of step-to-step instructions.

Thanks!

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 Post subject: Re: Propositional Logic ProblemsPosted: Wed, 6 Oct 2010 16:57:46 UTC
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Joined: Mon, 29 Dec 2008 17:49:32 UTC
Posts: 6007
Location: 127.0.0.1, ::1 (avatar courtesy of UDN)
cvkz wrote:
Use propositional logic to prove that the statement is valid:

1) [A → (B → C)] ^ (A V ~D) ^ B → (D → C)
2) (A → B) ^ [B → (C → D)] ^ [A → (B → C)] → (A → D)
3) A V B, A → C, B → C → C

Hope to get some help by getting some sort of step-to-step instructions.

Thanks!

First, you need a lot more brackets/parentheses.

How much propositional logic do you know? In particular, if you know the soundness and completeness theorem of first order propositional calculus then you can do with a truth table. If not, are you allowed to use derived argument form or just modus ponen?

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