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Math Help - simple natural deduction problems

  1. #1
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    simple natural deduction problems

    Hi, I am very new to logic and would like to know the solutions for these problems

    1. p -> (q -> p)

    It seems that I should assume that q is true but not too sure what to do..

    since this simple problem cannot be solved:

    2. ((p v q) -> q)
    -----------------
    ( p -> (p /\ q) )

    I want to know the answer for this too...

    Thank you very much sir.

    I want to answer to be in fitch style.

    Best Wishes

    Sabotage
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  2. #2
    MHF Contributor
    Joined
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    Re: simple natural deduction problems

    Code:
    1.   p			Assumption
    2.     q		Assumption
    3.     p 		1
    4.   q -> p		2-3, ->I
    5. p -> (q -> p)	1-4, ->I
    Code:
    1. (p \/ q) -> q	Assumption
    2.   p			Assumption
    3.   p \/ q		2, \/I
    4.   q			1,3, ->E
    5.   p /\ q		2,4, /\I
    6. p -> (p /\ q)	2-5, ->I
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