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Need help with verification of 5 symbolic logic sentences

  1. Nov 9, 2007 #1
    Please I need help with these 5 logical sentences. I have some basic ideas about logic, but was never good in it, and now we have to do it for our informatic lectures, please help me. I just have to say if the sentences are true or not.

    Thank you very much

    Attached Files:

  2. jcsd
  3. Nov 9, 2007 #2


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    Science Advisor
    Homework Helper

    I'll give you the first one, hoping that will get you started on the rest.
    For the first one, the implication from right to left is clear: if a is true, then certainly "a or (anything else)" is true.
    Now for the other way. What happens if one of the possibilities -- say the first -- is true? And what if it is false?

    If you are having trouble arguing here, you could make a truth table:
    Code (Text):

    a b av(~(b&a)) (...)=>a
    T T      T            ?
    T F      T            ?
    F T      T            ?
    F F      T            ?
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