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Homework Help: Logic: Natural Deducation

  1. Feb 14, 2012 #1
    Logic: Natural Deduction


    Can anyone lead me off here? I've broken down the three premises using 'for all' elimination, now I need to start a subderivation with an assumption, but I'm not sure what!

    Right now I'm unsure of the strategy I need to use to get to the conclusion, what do I want to be left with to manipulate into the conclusion?

    Would be grateful for any help!

    A list of the inference rules I have learnt so far for Natural deduction can be found HERE
    Last edited: Feb 14, 2012
  2. jcsd
  3. Feb 14, 2012 #2

    I've reduced the problem to the above, if I can prove the above then I can prove the whole thing! (I think..!)

    Any help on this one? Thanks :)
    Last edited: Feb 14, 2012
  4. Feb 15, 2012 #3
    Apparantly my above inference isn't valid so I cannot proceed with this method

    My initial assumption is assuming P(a,b) & P(b,a)

    Really stuck, would appreciate help!

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