## Abstract

Let A_{1},…, A_{n}, A_{n+1} be a finite sequence of algebras of sets given on a set X, (Formula Presented), with more than (Formula Presented) pairwise disjoint sets not belonging to A_{n+1}. It has been shown in the author's previous articles that in this case (Formula Presented). Let us consider, instead of A_{n+1}, a finite sequence of algebras A_{n+1},…, A_{n+l}. It turns out that if for each natural i ≤ l there exist no less than (Formula Presented) pairwise disjoint sets not belonging to A_{n+i}, then (Formula Presented). Besides this result, the article contains: an essentially important theorem on a countable sequence of almost σ-algebras (the concept of almost σ-algebra was introduced by the author in 1999), a theorem on a family of algebras of arbitrary cardinality (the proof of this theorem is based on the beautiful idea of Halmos and Vaughan from their proof of the theorem on systems of distinct representatives), a new upper estimate of the function v(n) that was introduced by the author in 2002, and other new results.

Original language | English |
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Pages (from-to) | 51-57 |

Number of pages | 7 |

Journal | Electronic Research Announcements of the American Mathematical Society |

Volume | 10 |

Issue number | 6 |

DOIs | |

State | Published - 26 May 2004 |

## Keywords

- Algebra on a set
- Almost σ-algebra
- Pairwise disjoint sets
- Ultrafilter