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Additivity of derived limits in the Cohen model

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arxiv 2302.07222 v4 pith:OMCWYENA submitted 2023-02-14 math.LO

classification math.LO
keywords derivedlimitsadditivitybergfalkcohenresultsjeffreylambie-hanson
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abstract

We show that, in the model constructed by adding sufficiently many Cohen reals, derived limits are additive on a large class of systems. This generalizes the work of Jeffrey Bergfalk, Michael Hru\v s\'ak, and Chris Lambie-Hanson which focuses on the system $\mathbf{A}$. In the process, we isolate a partition principle responsible for the vanishing of derived limits on collections of Cohen reals and reframe the propagating trivializations results of Bergfalk, Hru\v s\'ak and Lambie-Hanson as a theorem of ZFC. In light of results of the author, Jeffrey Bergfalk, and Justin Moore, the additivity of derived limits also implies additivity results for strong homology.

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Cited by 4 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Higher limits of wider systems

    math.LO 2025-07 unverdicted novelty 8.0 of 10

    Under GCH plus diamond principles, and in Gödel's constructible universe, the higher derived limits lim^n A_λ are nonzero for every cardinal λ where Goblot's vanishing theorem does not force them to zero.

  2. Simultaneously nonvanishing higher derived limits

    math.LO 2024-11 accept novelty 7.0 of 10

    If the dominating number equals aleph_n, then the n-th derived limit lim^n A[Z^(aleph_n)] is nonzero; and it is consistent that lim^k A is nonzero for every finite k >= 2, with continuum aleph_{omega+2}.

  3. Merging $\lim^1 \mathbf{A} \ne 0$ with other nonvanishing constructions

    math.LO 2026-07 accept novelty 6.5 of 10

    It is consistent that b=d=ω_n and lim^k A ≠ 0 for all 1≤k≤n, and that b=d=ω_{ω+2} with lim^k A ≠ 0 for every k≥1, by new forcings for lim^1 A ≠ 0 compatible with prior nonvanishing methods.

  4. Infinitary combinatorics in condensed math and strong homology

    math.AT 2024-12 conditional novelty 6.0 of 10

    Higher derived limits of the systems A_kappa_lambda are shown to control non-fullness, non-additivity of strong homology, and non-compactness of products of compact projective condensed anima.

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