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Homework Help: Lub and glb of a set

  1. Dec 12, 2011 #1
    1. The problem statement, all variables and given/known data
    Two sets A and B.
    B contain al the upper bound of A.

    whats is the relationship between the lub of A and the glb of B

    2. Relevant equations

    3. The attempt at a solution

    I am little bit confused , help please
  2. jcsd
  3. Dec 12, 2011 #2
    I'm assuming we're talking about the real numbers.

    Does A=[0,1] and B=(1,∞) satisfy you're requirement?

    What about A=[0,1) and B=[1,∞)? In this case in particular, what is the lub of A?

    What about A=[0,1] and B=[1,∞)?

    And what about A=[0,1] and B=[.5,∞)?
    Last edited: Dec 12, 2011
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