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Thread: help with proof

  1. #1
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    help with proof

    First, I am not sure how to type the correct characters into this message block. I tried character map, but I had no luck. IF anyone wants to tell me if there is a language pack or add-on for this, feel free. Now the proof I am working on is as follows:
    prove that $\displaystyle A \subseteq B$ if and only if "the complement of B" $\displaystyle \subseteq $ "the complement of A"


    Can someone point me in the right direction? Again any help inputting the symbols is appreciated as well.
    Last edited by totalbs70; Jan 29th 2010 at 10:26 AM.
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  2. #2
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    Quote Originally Posted by totalbs70 View Post
    First, I am not sure how to type the correct characters into this message block. I tried character map, but I had no luck. IF anyone wants to tell me if there is a language pack or add-on for this, feel free.
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  3. #3
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    Quote Originally Posted by totalbs70 View Post
    prove that $\displaystyle A \subseteq B$ if and only if "the complement of B" $\displaystyle \subseteq $ "the complement of A"
    Notice that $\displaystyle P \to Q\,\, \equiv \,\neg Q \to \neg P$
    So $\displaystyle x \in P \to x \in Q\,\, \equiv \,x \notin Q \to x \notin P$
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