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Homework Help: Sets help interpreting question

  1. Feb 20, 2010 #1
    I have this question but I don't get it at all. Here goes:

    Let X be {x, y, z}
    P(X) is the power set.
    For all Y,Z is an element of P(X), Y R Z where The number of elements in Y intersect Z is 1.

    So I worked out P(X) to be:

    {(null), (x), (y), (z), (x,y), (x,z), (y,z)}

    Then I don't get the next line, how can the number of elements of Y intersect Z be 1 if all members of Y and Z are elements of P(X)? Isn't Y = Z?
     
  2. jcsd
  3. Feb 20, 2010 #2

    tiny-tim

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    Hi DorumonSg! :smile:

    (you missed out (x,y,z) :wink:)

    For example, (x,y) R (x,z) and (x,y) R (x) but not (x,y) R (z) and not (x,y) R (x,y,z). :smile:
     
  4. Feb 20, 2010 #3
    So Y R Z is supposed to be:

    {((x),(x,y)), ((x),(x,z)), ((x),(x,y,z)), ((y),(x,y)), ((y),(y,z)), ((y),(x,y,z)), ((z),(x,z)), ((z),(y,z)), ((z),(x,y,z)), ((x,y),(x,z)), ((x,y),(y,z)), ((x,z),(y,z))}

    You mean like that?
     
  5. Feb 20, 2010 #4

    tiny-tim

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  6. Feb 20, 2010 #5
    Thanks alot.

    Am I also right to say that Y R Z is not Reflective, Symmetric, Anti-Symmetric, Transitive, Partial Order and Total Order?
     
  7. Feb 20, 2010 #6

    tiny-tim

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    No..
     
  8. Feb 20, 2010 #7
    Eh? But I don't see any relations between them.
     
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