ArticleOriginal scientific text

Title

Prenormality of ideals and completeness of their quotient algebras

Authors 1, 1

Affiliations

  1. Mathematical Institute, Wrocław University, Pl. Grunwaldzki 2/4, 50-384 Wrocław, Poland

Abstract

It is well known that if a nontrivial ideal ℑ on κ is normal, its quotient Boolean algebra P(κ)/ℑ is κ+-complete. It is also known that such completeness of the quotient does not characterize normality, since P(κ)/ℑ turns out to be κ+-complete whenever ℑ is prenormal, i.e. whenever there exists a minimal ℑ-measurable function in ^{κ}κ. Recently, it has been established by Zrotowski (see [Z1], [CWZ] and [Z2]) that for non-Mahlo κ, not only is the above condition sufficient but also necessary for P(κ)/ℑ to be κ+-complete. In the present note we are going to visualize that Zrotowski's result is a consequence of the Boolean structure of P(κ) exclusively, rather than of its other particular properties.

Bibliography

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  2. [CWZ] J. Cichoń, B. Węglorz and R. Zrotowski, Some properties of filters. II, preprint no. 12, Mathematical Institute, Wrocław University, 1984.
  3. [J] T. Jech, Set Theory, Academic Press, New York 1978.
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Pages:
19-27
Main language of publication
English
Received
1988-11-30
Accepted
1990-05-25
Published
1993
Exact and natural sciences