hi dannidin -ga ,

   I request you to answer these questions.


1) Let (X,M,mu) be a measure space. Prove that mu is sigma finite if
and only if there exists  a mu-integrable function phi with
0<phi<infinity for all x belongs to X.

2) prove that lebesgue radon nikodym theorm in the case of two sigma
finite measures mu and nu.


 3) construct an example, showing that the lebesgue radon nikodym
theorm fails to be true if the measure mu is not assumed to be sigma
finite.