English

New consequences of PFA($T^*$)

Logic 2025-11-05 v2

Abstract

Let TT^* be an almost Suslin tree, that is, an Aronszajn tree with no stationary antichains. Krueger introduced a forcing axiom, PFA(T)\mathrm{PFA}(T^*), for the class of proper forcings that preserve that TT^* is almost Suslin. He showed that PFA(T)\mathrm{PFA}(T^*) implies several well-known consequences of the Proper Forcing Axiom (PFA\mathrm{PFA}), including Suslin's Hypothesis and the P-ideal dichotomy. We extend this list by proving that PFA(T)\mathrm{PFA}(T^*) also implies the Mapping Reflection Principle (MRP\mathrm{MRP}) and the Open Graph Axiom (OGA\mathrm{OGA}). Additionally, we show that PFA(T)\mathrm{PFA}(T^*) implies that all special Aronszajn trees are club-isomorphic, but it does not imply that all almost Suslin trees are club-isomorphic.

Keywords

Cite

@article{arxiv.2510.22807,
  title  = {New consequences of PFA($T^*$)},
  author = {Carlos Martínez-Ranero and Lucas Polymeris},
  journal= {arXiv preprint arXiv:2510.22807},
  year   = {2025}
}

Comments

v2: corrected citation to Lambie-Hanson's and Stejskalov\'a's article

R2 v1 2026-07-01T07:06:45.780Z