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Reaping Numbers of Boolean Algebras
Authors:Dow  Alan; Steprans  Juris; Watson  Stephen
Institution:Department of Mathematics York University 4700 Keele Street North York Ontario Canada M3J 1P3
Abstract:A subset A of a Boolean algebra B is said to be (n,m)-reapedif there is a partition of unity p sub B of size n such that |{bisin p:b {wedge} a != 0}| ≥ m for all a isin A. The reaping number rn,m (B) ofa Boolean algebra B is the minimum cardinality of a set A sub B\{0}which cannot be (n,m)-reaped. It is shown that for each nisin{omega}, thereis a Boolean algebra B such that rn+1,2(B) != rn,2(B). Also, {rn,m(B):m≤nisin {omega}} consists of at most two consecutive cardinals. The existenceof a Boolean algebra B such that rn,m (B) != rn',m' (B) is equivalentto a statement in finite combinatorics which is also discussed.
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