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-   -   Proof by induction (https://www.askmehelpdesk.com/showthread.php?t=11505)

  • Aug 3, 2005, 08:07 AM
    angora
    Proof by induction
    How can I prove the following?
    for any integer n>=1,
    {celling of [lg(n+1)]} = (floor of lg n) + 1
    thanks for the help
  • Sep 4, 2005, 10:52 AM
    reinsuranc
    Hi. I understand induction, but I am confused.

    Is lg supposed to be logarithm?

    What is celling? Is this supposed to be ceiling?

    What do ceiling and floor have to do with logarithms?

    Maybe you can restate this problem.
  • Sep 4, 2005, 01:46 PM
    CroCivic91
    "lg x" is short for "logarithm of x with the base 2".

    "Celling" should indeed be "ceiling". "Ceiling" is a function that takes a real number and returns an integer, in the following rule:

    ceiling( x ) = min{ n : n >= x & n is an integer }
    For example, ceiling( pi ) = 4, ceiling( -pi ) = -3

    "Floor" is a function defined as:

    floor( x ) = max{ n : n <= x & n is an integer }
    For example, floor( pi ) = 3, floor( -pi ) = -4

    Of course, floor( 3 ) = 3, and ceiling( 3 ) = 3.

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