We study principles of the form: if a name sigma is forced to have a certain property phi, then there is a ground model filter g such that sigma g satisfies phi. We prove a general correspondence connecting these name principles to forcing axioms. Special cases of the main theorem are: center dot Any forcing axiom can be expressed as a name principle. For instance, PFA is equivalent to: center dot A principle for rank 1 names (equivalently, nice names) for subsets of omega 1. center dot A principle for rank 2 names for sets of reals. center dot lambda-bounded forcing axioms are equivalent to name principles. Bagaria's characterisation of BFA via generic absoluteness is a corollary. We further systematically study name principles where phi is a notion of largeness for subsets of omega 1 (such as being unbounded, stationary or in the club filter) and corresponding forcing axioms.
Henney-Turner, C., Schlicht, P. (2023). Forcing axioms via ground model interpretations. ANNALS OF PURE AND APPLIED LOGIC, 174(6), 1-45 [10.1016/j.apal.2023.103260].
Forcing axioms via ground model interpretations
Schlicht, Philipp
2023-01-01
Abstract
We study principles of the form: if a name sigma is forced to have a certain property phi, then there is a ground model filter g such that sigma g satisfies phi. We prove a general correspondence connecting these name principles to forcing axioms. Special cases of the main theorem are: center dot Any forcing axiom can be expressed as a name principle. For instance, PFA is equivalent to: center dot A principle for rank 1 names (equivalently, nice names) for subsets of omega 1. center dot A principle for rank 2 names for sets of reals. center dot lambda-bounded forcing axioms are equivalent to name principles. Bagaria's characterisation of BFA via generic absoluteness is a corollary. We further systematically study name principles where phi is a notion of largeness for subsets of omega 1 (such as being unbounded, stationary or in the club filter) and corresponding forcing axioms.File | Dimensione | Formato | |
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https://hdl.handle.net/11365/1277499