1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook