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Homework Help: Proof Theory for all real numbers

  1. Mar 24, 2008 #1
    [SOLVED] Proof Theory for all real numbers

    1. The problem statement, all variables and given/known data

    If a and b are real numbers, we define max {a, b} to be the maximum of a and b or the common value if they are equal.

    Prove that for all real numbers d, d1, d2, x, If d = max {d1, d2} and x ≥ d, then x ≥ d1 and x ≥ d2.

    2. Relevant equations

    3. The attempt at a solution

    I do not know how to even start this problem, i have a small feeling that this exercise has something in relation with the "Logic and propositional calculus topic" but i have not find out were to link it. Any hint or good start will be appreciated.

    Thanks :redface:
  2. jcsd
  3. Mar 24, 2008 #2


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    Science Advisor

    Why in the world is this in "Engineering, Computer Science, and Technology"? Looks like a straightforward math problem to me. First, we have, from the definition, [itex]max(d_1,d_2)\ge d1[/itex] and [itex]max(d_1,d_2)\ge d2[/itex]. It follows immediately that if [itex]x\ge max(d1,d2)[/itex] then [itex]x\ge d1[/itex] and [itex]x\ge d2[/itex].
  4. Mar 25, 2008 #3
    Thank you very much "HallsofIvy" i put it here since its a "Computer Science Class" at my college, I am currently studying "Computer Engineer" and i have to take this class.

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