Question about probability measure

[Alexsandro]

An probability measure on same space \Omega is a function of subsets of \Omega satisfying three axioms:

(i) For every set A \subset \Omega, the value of the function is a non-negative number: P(A) \geqslant 0.

(ii) For any two disjoint sets A and B, the value of the function for their union A + B is equal to the sum of its value for A and its value for B:

P(A + B) = P(A) + P(B) provided A.B = {\O}.

(iii) The value of the function for \Omega (as a subset) is equal to 1:

P(\Omega) = 1.


Now, reply these questions:

If M is a probability measure, show:

(a) that the function M/2 satisfies Axiom(i) and (ii) but not (iii).

(b) the function M^2 satisfies (i) and (iii) but not necessary (ii); give a counterexample to (ii).

 

[Hurkyl]

We can't help if you if you haven't tried it.

 

[David]

See how I do one of these examples in: https://www.physicsforums.com/showpost.php?p=739271&postcount=4

That should point you in the right direction.

 

[Alexsandro]

See how I do one of these examples in: https://www.physicsforums.com/showpost.php?p=739271&postcount=4

That should point you in the right direction.

David,

Thanks, for your help. Can you help me to find a counterexample for item b this question. I am not getting to find it.

 

[sic]

Omega={A,B}
M(gurnisht)=0
M({A})=1/2
M({B})=1/2
M({A,B})=1
then
M^2({A,B})!=M^2({A})+M^2({B})
(Either it's that simple or i don't understand the problem)