EPR-correlation

[kleinwolf]

What about incomplete measurement, is it measuring A without measuring B...does this disturbs B ? From axioms we get : [math]A\otimes 1[/math], hence the system in B, whenever defined as such locally, is not disturbed, however, from the postulate of QM (generallier) : a measurment disturbs the system, and the system in B is in some sense disturbed "in a undefined way"...does this is "incomplete measurement"

 

(In fact I ask this question because of the definition of covariance, in Bell's theorem : Cov(A,B)=<AB>-<A><B>)..what does <A> in formula looks like, it has no sense since the system is of dimension 4 and A is 2-dimensional)