MathOverflow is a question and answer site for professional mathematicians. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Hi ;

i have this theorem from the book :Set-valued analysis

Let $(\Omega,\mathcal{A},\mu)$ be a complete $\sigma$-finite measure space , $X$ a complete separable metric space and $G\in\mathcal{A}\times > \mathcal{B}(X)$ . Then it's projection $pr_{\Omega}(G)=\lbrace t\in \Omega > ,\exists x\in X, (t,x)\in G\rbrace \in > \mathcal{A} $

there is a prove of this in the book of Castaing "convexe and measurable multifunction" in chapter 3 but i dont understand it

please help me

Thank you .

share|cite|improve this question
Well there is the obvious advice: Try another book! Also: This is not the kind of question that is appropriate for MathOverflow. Consider asking it on other sites like – Johannes Hahn Apr 11 '13 at 12:47
how i must ask it ? please – karima Apr 11 '13 at 12:52
have you another book ? – karima Apr 11 '13 at 13:02
A tangential side-note. We see questions from time to time asking why we care if a measure space is complete. Here is one example: this projection result fails in general with an incomplete measure. – Gerald Edgar Apr 11 '13 at 13:15
About half a year ago I scribbled in my notebooks that the measurable projection theorem can be found in the fourth volume of Fremlin's books. But unfortunately I didn't write down the page number. If you just google the phrase "measurable projection theorem" you will also find a wealth of information. – Willie Wong Apr 11 '13 at 15:38

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.