Re: FOL Deduction Question

From: Zarius (me_at_privacy.net)
Date: 12/23/04

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    Date: Thu, 23 Dec 2004 19:14:46 +0000

    (opss prematurely sent the other answer)

    > If by falsifying you mean deriving the empty sequent, then this
    > is impossible since the system is sound (Lemma 5.4.3).

    Nope, for that simple sequent falsifying reduces to showing the right hand
    side formula is not a tautology, that is a valuation v exists such that,
    v |= ~(Exists x . P(x))

    Since the system is sound and complete I want build a counter-example
    deduction tree for that sequent.

    > I hope I haven't confused you. If this is the first time you meet
    > predicate logic, then you should look for another introductory text,
    > since Gallier's book seems rather sophisticated.
    >
    > Regards.
    > José Juan Mendoza Rodríguez

    Thanks for answering, you did explain everything very well. I do have
    experience experience with predicate logic, though, no worries there (I
    hope). It's was automated deduction question.

    Cheers,
    J.A.

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