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Math Help - Partial orders

  1. #1
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    Partial orders

    State whether the following relations is a partial order

    isAncestorOf

    isSisterOf

    {(2,1),(1,3)(2,3)}
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  2. #2
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    Quote Originally Posted by cj's mom View Post
    State whether the following relations is a partial order

    isAncestorOf

    isSisterOf

    {(2,1),(1,3)(2,3)}
    Why don't you tell us what you think the answers are?
    That way we can better help you with any missunderstanding.
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  3. #3
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    I thought it was

    yes

    no

    yes

    but I wanted to check it out.
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  4. #4
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    Quote Originally Posted by cj's mom View Post
    I thought it was

    yes

    no

    yes

    but I wanted to check it out.
    Can you explain those answers?
    Be sure you check each as to being reflexive, antisymmetric and transitive.
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  5. #5
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    Partial order

    I looked at the relations
    is Ancestor of
    A is an ancestor of A = reflexive
    if A is an ancestor of B then B is not an ancestor of A
    if A is an ancestor of B and B is an ancestor of C then A is an ancestor of C.

    The one I am stuck on is the antisymmetric.

    Looking back I think the first two are yes and the last one is no
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  6. #6
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    Quote Originally Posted by cj's mom View Post
    I looked at the relations
    is Ancestor of
    A is an ancestor of A = reflexive
    Do you really think that you are an ancestor of yourself?
    Maybe we have different definitions of ancestor.
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  7. #7
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    partial

    okay I give up
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  8. #8
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    Quote Originally Posted by cj's mom View Post
    okay I give up
    No, don't give up.
    This is either a badly worded question or you did not take time to type up the exact question.
    Usually a well written question would have given the domain of the relation.
    Moreover, it is not good form to use such term as ancestor without defining it.
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  9. #9
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    partial

    That is the way it is written with no other information.
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