TY - JOUR
T1 - On a superatomic Boolean algebra which is not generated by a well-founded sublattice
AU - Abraham, Uri
AU - Rubin, Matatyahu
AU - Bonnet, Robert
PY - 2001/1/1
Y1 - 2001/1/1
N2 - Let b denote the unboundedness number of ωω. That is, b is the smallest cardinality of a subset F ⊆ ωω such that for every g ∈ ωω there is f ∈ F such that {n: g(n) ≤ f(n)} is infinite. A Boolean algebra B is well-generated, if it has a well-founded sublattice L such that L generates B. We show that it is consistent with ZFC that א1 < 2א0 = b, and there is a Boolean algebra B such that B is not well-generated, and B is superatomic with cardinal sequence 〈א0, א1, א1, 1〉. This result is motivated by the fact that if the cardinal sequence of a Boolean algebra B is 〈א0, א0, λ, 1〉, and B is not well-generated, then λ ≥ b.
AB - Let b denote the unboundedness number of ωω. That is, b is the smallest cardinality of a subset F ⊆ ωω such that for every g ∈ ωω there is f ∈ F such that {n: g(n) ≤ f(n)} is infinite. A Boolean algebra B is well-generated, if it has a well-founded sublattice L such that L generates B. We show that it is consistent with ZFC that א1 < 2א0 = b, and there is a Boolean algebra B such that B is not well-generated, and B is superatomic with cardinal sequence 〈א0, א1, א1, 1〉. This result is motivated by the fact that if the cardinal sequence of a Boolean algebra B is 〈א0, א0, λ, 1〉, and B is not well-generated, then λ ≥ b.
UR - http://www.scopus.com/inward/record.url?scp=0009919878&partnerID=8YFLogxK
U2 - 10.1007/BF02784128
DO - 10.1007/BF02784128
M3 - Article
AN - SCOPUS:0009919878
SN - 0021-2172
VL - 123
SP - 221
EP - 239
JO - Israel Journal of Mathematics
JF - Israel Journal of Mathematics
ER -