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Math Help - Reflexive relation

  1. #1
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    Reflexive relation

    Is x=-/+y reflexive? (x, y) exists in R, on a set of all real numbers.

    Sorry, don't know how to put in the positive or negative symbol.

    I'm thinking it is, but I don't know how to express it in a proof.

    Thanks!
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  2. #2
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    Quote Originally Posted by SlapnutsGT View Post
    Is x=-/+y reflexive? (x, y) exists in R
    Is this true \forall x \in \mathbb{R}: both of these pairs (x,x)~\&~(x,-x) are in the relation?
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  3. #3
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    Quote Originally Posted by Plato View Post
    Is this true \forall x \in \mathbb{R}: both of these pairs (x,x)~\&~(x,-x) are in the relation?
    I would assume yes, because it exists in a set of all real numbers. Only info given is:
    Determine whether the relation R on the set of all real numbers is reflexive, symmetric, antisymmetric, and/or transitive, where (x, y) \in \mathbb{R} if and only if x=\pm\,y.
    Last edited by Plato; April 16th 2009 at 08:20 AM.
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  4. #4
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    Quote Originally Posted by SlapnutsGT View Post
    I would assume yes, because it exists in a set of all real numbers. Only info given is:
    Determine whether the relation R on the set of all real numbers is reflexive, symmetric, antisymmetric, and/or transitive, where (x, y) \in \mathbb{R} if and only if x=\pm\,y.
    You missed my point. If the answer is yes then it is reflexive.

    BTW: To get \pm type [tex]\pm[/tex]
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  5. #5
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    Doh! I can be a knucklehead sometimes, kinda missed your point because I'm struggling to understand discrete math. Math without numbers is still a new concept to me! Thanks you for the help!
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