TY - JOUR

T1 - Point-cofinite covers in the laver model

AU - Miller, Arnold W.

AU - Tsaban, Boaz

PY - 2010/9

Y1 - 2010/9

N2 - Let S1(Γ, Γ) be the statement: For each sequence of point-cofinite open covers, one can pick one element from each cover and obtain a point-cofinite cover. b is the minimal cardinality of a set of reals not satisfying S1(Γ, Γ). We prove the following assertions: (1) If there is an unbounded tower, then there are sets of reals of cardinality b satisfying S1(Γ, Γ). (2) It is consistent that all sets of reals satisfying S1(Γ, Γ) have cardinality smaller than b. These results can also be formulated as dealing with Arhangel'skiǐ's property α2 for spaces of continuous real-valued functions. The main technical result is that in Laver's model, each set of reals of cardinality b has an unbounded Borel image in the Baire space ωω.

AB - Let S1(Γ, Γ) be the statement: For each sequence of point-cofinite open covers, one can pick one element from each cover and obtain a point-cofinite cover. b is the minimal cardinality of a set of reals not satisfying S1(Γ, Γ). We prove the following assertions: (1) If there is an unbounded tower, then there are sets of reals of cardinality b satisfying S1(Γ, Γ). (2) It is consistent that all sets of reals satisfying S1(Γ, Γ) have cardinality smaller than b. These results can also be formulated as dealing with Arhangel'skiǐ's property α2 for spaces of continuous real-valued functions. The main technical result is that in Laver's model, each set of reals of cardinality b has an unbounded Borel image in the Baire space ωω.

UR - http://www.scopus.com/inward/record.url?scp=77953337394&partnerID=8YFLogxK

U2 - 10.1090/s0002-9939-10-10407-9

DO - 10.1090/s0002-9939-10-10407-9

M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???

SN - 0002-9939

VL - 138

SP - 3313

EP - 3321

JO - Proceedings of the American Mathematical Society

JF - Proceedings of the American Mathematical Society

IS - 9

ER -