Understanding Lebesgue Measure: Example of Open Intervals on [0,1]

  • Thread starter Thread starter tomprice
  • Start date Start date
  • Tags Tags
    Measure
AI Thread Summary
The discussion revolves around the confusion regarding Lebesgue measure, particularly the outer measure of rational numbers being zero. A user initially seeks examples of open intervals that cover the rationals in [0, 1] while having a total length of less than 1. They reference the definition of Lebesgue outer measure, which suggests such intervals should exist. Ultimately, the user resolves their confusion and retracts their request for assistance. The topic highlights the nuances of Lebesgue measure and its implications in measure theory.
tomprice
Messages
18
Reaction score
0
I am confused about lebesgue measure.

I have heard that the lebesgue outer measure of the rational numbers is 0.

So could someone please give an example of a set of open intervals such that:

a. The union of these intervals contains the rational numbers on [0, 1]

b. The sum of lengths of these intervals is less than 1.

The definition of lebesgue outer measure implies that, if the lebesgue outer measure of the rationals is 0, then such a set of open intervals must exist. But I am flabberghasted as to how this could be so.

Thanks very much in advance.
 
Physics news on Phys.org
false alarm

Nevermind I got it.
 
I was reading documentation about the soundness and completeness of logic formal systems. Consider the following $$\vdash_S \phi$$ where ##S## is the proof-system making part the formal system and ##\phi## is a wff (well formed formula) of the formal language. Note the blank on left of the turnstile symbol ##\vdash_S##, as far as I can tell it actually represents the empty set. So what does it mean ? I guess it actually means ##\phi## is a theorem of the formal system, i.e. there is a...
Back
Top