English

Reaping Numbers of Boolean Algebras

Logic 2008-02-03 v1

Abstract

A subset AA of a Boolean algebra BB is said to be (n,m)(n,m)-reaped if there is a partition of unity PBP \subset B of size nn such that the cardinality of {bP:ba}\{b \in P: b \wedge a \neq \emptyset\} is greater than or equal to mm for all aAa\in A. The reaping number rn,m(B)r_{n,m}(B) of a Boolean algebra BB is the minimum cardinality of a set AB{0}A \subset B\setminus \{0\} such which cannot be (n,m)(n,m)-reaped. It is shown that, for each nωn \in \omega, there is a Boolean algebra BB such that rn+1,2(B)rn,2(B)r_{n+1,2}(B) \neq r_{n,2}(B). Also, {rn,m(B):{n,m}ω}\{r_{n,m}(B) : \{n,m\}\subseteq\omega\} consists of at most two consecutive integers. The existence of a Boolean algebra BB such that rn,m(B)rn,m(B)r_{n,m}(B) \neq r_{n',m'}(B) is equivalent to a statement in finite combinatorics which is also discussed.

Keywords

Cite

@article{arxiv.math/9204210,
  title  = {Reaping Numbers of Boolean Algebras},
  author = {A. Dow and J Steprāns and W. S. Watson},
  journal= {arXiv preprint arXiv:math/9204210},
  year   = {2008}
}
R2 v1 2026-07-22T17:53:49.500Z