Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Non-measurable sets

  1. Oct 25, 2009 #1
    are there lots of examples of non-measurable sets? the one that seems to be in most textbooks involves a type of addition mod an irrational number with equivalence classes, etc etc, which in some books is done geometrically as rotations of a circle through an irrational angle. that example was by vitali, but there is another one by edward van vleck where he constructs two subsets of (0,1) in a way that either the measure of one is 1 & the other has measure 0, or they both have what he called "upper measure" =1, & therefore they're both non-measurable. how many other ones are out there that I don't know about?
  2. jcsd
  3. Oct 25, 2009 #2
    My favorite is due to Bernstein.

    You construct (by transfinite induction) a set B so that both B and its complement meet every uncountable closed set.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook