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propositional logic proofs

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  • 14-05-2012 8:46pm
    #1
    joey12345
    Registered Users Posts: 49 ✭


    any one here decent at explaining proofs with propositional logic?

    i have one here

    if A={p->q, r v q, ~r} then A logically implies q

    not looking for answers just a very easy explanation..

    so far i have

    1. p->q H
    2. r v p H
    3. ~r H
    4. [p] A
    5. q 1,4 MP
    .
    .
    .
    .
    .
    im terrible at logic as you can see. any help would be great this sort of question seems to appear every year so itd be great for a bit of help
    Tagged:


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    #2
    MathsManiac
    Registered Users Posts: 1,595 ✭✭✭MathsManiac


    Every course in logic seems to be slightly different in a number of respects, and I'm not sure what axiom set you have governing/defining such things as "v", and I'm not sure of some of your notation, but your line 4 looks dubious.

    Ignoring the first item in A, you should be able to use r v q and ~r to deduce q.


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