3 research outputs found
Adding many Baumgartner clubs
I define a homogeneous ℵ2–c.c. proper product forcing for adding many clubs of ω1 with finite conditions. I use this forcing to build models of b(ω1)=ℵ2, together with d(ω1) and 2ℵ0 large and with very strong failures of club guessing at ω1
A forcing notion collapsing \aleph_3 and preserving all other cardinals
I construct, in ZFC, a forcing notion that collapses \aleph_3 and preserves all other cardinals. The existence of such a forcing answers a question of Uri Abraham from 1983
Separating club-guessing principles in the presence of fat forcing axioms
We separate various weak forms of Club Guessing at in the presence of large, Martin's Axiom, and related forcing axioms. We also answer a question of Abraham and Cummings concerning the consistency of the failure of a certain polychromatic Ramsey statement together with the continuum large. All these models are generic extensions via finite support iterations with symmetric systems of structures as side conditions, possibly enhanced with -sequences of predicates, and in which the iterands are taken from a relatively small class of forcing notions. We also prove that the natural forcing for adding a large symmetric system of structures (the first member in all our iterations) adds -many reals but preserves CH