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Transactions of the American Mathematical Society

Published by the American Mathematical Society since 1900, Transactions of the American Mathematical Society is devoted to longer research articles in all areas of pure and applied mathematics.

ISSN 1088-6850 (online) ISSN 0002-9947 (print)

The 2020 MCQ for Transactions of the American Mathematical Society is 1.48.

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Where pigeonhole principles meet König lemmas
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by David Belanger, C. T. Chong, Wei Wang, Tin Lok Wong and Yue Yang PDF
Trans. Amer. Math. Soc. 374 (2021), 8275-8303 Request permission

Abstract:

We study the pigeonhole principle for $\Sigma _2$-definable injections with domain twice as large as the codomain, and the weak König lemma for $\Delta ^0_2$-definable trees in which every level has at least half of the possible nodes. We show that the latter implies the existence of $2$-random reals, and is conservative over the former. We also show that the former is strictly weaker than the usual pigeonhole principle for $\Sigma _2$-definable injections.
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Additional Information
  • David Belanger
  • Affiliation: Institute for Mathematical Sciences, National University of Singapore, Singapore 118402
  • MR Author ID: 922507
  • Email: belanger@nus.edu.sg
  • C. T. Chong
  • Affiliation: Department of Mathematics, National University of Singapore, Singapore 119076
  • MR Author ID: 48725
  • ORCID: 0000-0002-0800-7747
  • Email: chongct@nus.edu.sg
  • Wei Wang
  • Affiliation: Institute of Logic and Cognition and Department of Philosophy, Sun Yat-Sen University, Guangzhou, People’s Republic of China
  • Email: wwang.cn@gmail.com
  • Tin Lok Wong
  • Affiliation: Department of Mathematics, National University of Singapore, Singapore 119076
  • MR Author ID: 825514
  • Email: matwong@nus.edu.sg
  • Yue Yang
  • Affiliation: Department of Mathematics, National University of Singapore, Singapore 119076
  • Email: matyangy@nus.edu.sg
  • Received by editor(s): January 18, 2020
  • Received by editor(s) in revised form: June 15, 2021
  • Published electronically: August 25, 2021
  • Additional Notes: The first author was partially supported by BOF grant number 01P01117.
    The second author’s research was partially supported by NUS grants C-146-000-042-001 and WBS : R389-000-040-101.
    The third author was partially supported by China NSF Grants 11471342 and 11971501.
    The fourth author was financially supported by the Singapore Ministry of Education Academic Research Fund Tier 2 grant MOE2016-T2-1-019 / R146-000-234-112 when this research was carried out.
    The fifth author was partially supported by Singapore MOE grant MOE-2019-t2-2-121.
    All the authors acknowledge the support of JSPS–NUS grants R146-000-192-133 and R146-000-192-733 during the course of the work.
  • © Copyright 2021 American Mathematical Society
  • Journal: Trans. Amer. Math. Soc. 374 (2021), 8275-8303
  • MSC (2020): Primary 03B30, 03F35, 03F30, 03D32
  • DOI: https://doi.org/10.1090/tran/8494
  • MathSciNet review: 4328699