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Difference between revisions of "Independent measurable decompositions"

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''independent measurable partitions, of a space with a normalized measure''
 
''independent measurable partitions, of a space with a normalized measure''
  
Two measurable partitions <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i0506101.png" /> and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i0506102.png" /> such that if <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i0506103.png" /> and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i0506104.png" /> are Boolean <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i0506105.png" />-algebras of measurable sets consisting entirely of elements of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i0506106.png" /> and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i0506107.png" />, respectively, then the elements of one of them are independent of the elements of the other in the sense of probability theory: <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i0506108.png" /> for <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i0506109.png" />, <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i05061010.png" />. Under these conditions, if a measurable partition that is a refinement of both <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i05061011.png" /> and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i05061012.png" /> coincides <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i05061013.png" /> with the partition into single points, then <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i05061014.png" /> and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/i/i050/i050610/i05061015.png" /> are said to be independent complements of one another. Conditions are known for a measurable partition of a [[Lebesgue space|Lebesgue space]] to have an independent complement.
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Two measurable partitions $\xi$ and $\eta$ such that if $B(\xi)$ and $B(\eta)$ are Boolean $\sigma$-algebras of measurable sets consisting entirely of elements of $\xi$ and $\nu$, respectively, then the elements of one of them are independent of the elements of the other in the sense of probability theory: $\mu(A\cap B)=\mu(A)\mu(B)$ for $A\in B(\xi)$, $B\in B(\eta)$. Under these conditions, if a measurable partition that is a refinement of both $\xi$ and $\eta$ coincides $\bmod\,0$ with the partition into single points, then $\xi$ and $\eta$ are said to be independent complements of one another. Conditions are known for a measurable partition of a [[Lebesgue space|Lebesgue space]] to have an independent complement.
  
 
====References====
 
====References====

Latest revision as of 18:07, 3 August 2014

independent measurable partitions, of a space with a normalized measure

Two measurable partitions $\xi$ and $\eta$ such that if $B(\xi)$ and $B(\eta)$ are Boolean $\sigma$-algebras of measurable sets consisting entirely of elements of $\xi$ and $\nu$, respectively, then the elements of one of them are independent of the elements of the other in the sense of probability theory: $\mu(A\cap B)=\mu(A)\mu(B)$ for $A\in B(\xi)$, $B\in B(\eta)$. Under these conditions, if a measurable partition that is a refinement of both $\xi$ and $\eta$ coincides $\bmod\,0$ with the partition into single points, then $\xi$ and $\eta$ are said to be independent complements of one another. Conditions are known for a measurable partition of a Lebesgue space to have an independent complement.

References

[1] V.A. Rokhlin, "On the main notions of measure theory" Mat. Sb. , 25 : 1 (1949) pp. 107–150 (In Russian)
[2] M.P. Ershov, "Rokhlin's theorem on independent complementation" Uspekhi Mat. Nauk , 32 : 1 (1977) pp. 187–188 (In Russian)


Comments

See also Measurable decomposition.

References

[a1] I.P. [I.P. Kornfel'd] Cornfel'd, S.V. Fomin, Ya.G. Sinai, "Ergodic theory" , Springer (1982) (Translated from Russian)
[a2] W. Parry, "Topics in ergodic theory" , Cambridge Univ. Press (1981)
How to Cite This Entry:
Independent measurable decompositions. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Independent_measurable_decompositions&oldid=11775
This article was adapted from an original article by D.V. Anosov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article