Abstract
Let TT1 be the combinatorial principle stating that every finite coloring of the infinite full binary tree has a homogeneous isomorphic subtree. Let RT 22 and WKL0 denote respectively the principles of Ramsey’s theorem for pairs and the weak König lemma. It is proved that TT1 + RT 22 + WKL0 is Π 03 -conservative over the base system RCA0. Thus over RCA0, TT1 and Ramsey’s theorem for pairs prove the same Π 03 -sentences.
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All the authors acknowledge the support of the NUS Institute for Mathematical Sciences where the work began. The authors thank the referee for helpful suggestions.
Chong’s research was partially supported by NUS grants C-146-000-042-001 and WBS: R389-000-040-101.
Wang’s research was partially supported by China NSF Grant 11971501.
Yang’s research was partially supported by MOE2019-T2-2-121.
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Chong, C.T., Wang, W. & Yang, Y. Conservation strength of the infinite pigeonhole principle for trees. Isr. J. Math. (2023). https://doi.org/10.1007/s11856-023-2567-8
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DOI: https://doi.org/10.1007/s11856-023-2567-8