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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Kernel-checked finite exclusions for odd covering systems

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capacity_prod_relax: Shows that removing coprime covering classes can only increase the uncovered-count bound.

enumeration: Checks every odd period up to ten thousand and excludes all non-deficient candidates.

evidence/: Exact integer replay of the odd-covering exclusion: the finite enumeration below 10000 and its 23 strict capacity inequalities.

formal_bridge: Identifies the integer objects behind the source's transport to the formal-conjectures vocabulary.

lemma_4_1: Counts residue classes in one period to bound their total reciprocal density.

lemma_4_2: Shows that a common multiple supporting distinct nontrivial covering moduli is non-deficient.

lemma_4_3: Uses the Chinese remainder theorem to count points avoiding pairwise coprime classes.

odd_covering_lcm_gt_10000: Combines density, exhaustive enumeration and capacity certificates to exclude all smaller odd periods.

periodicity: Relates integer coverings and exclusions to their exact finite residue checks.

theorem_4_4: Refutes every distinct covering supported on a period when the remaining divisor budget is too small.


Ibrahim Mian and Shayaan Siddique, Kernel-Checked Exclusions for the Erdős–Selfridge Odd Covering Problem: Any Odd Covering of Z Has lcm Exceeding 10000, arXiv:2607.25628v1, 28 July 2026, 11 pages. The canonical PDF is this version. The arXiv record, lists only v1. No journal publication or later-paper equivalence is asserted here. The arXiv record (https://arxiv.org/abs/2607.25628, read 2026-10-02) names the Creative Commons Attribution 4.0 license.

Mathematical contribution and complete proof chain

Every finite covering of the integers by distinct odd moduli greater than one must have least common multiple above 10000. The authors describe this mathematical bound as known; their contribution is its Lean formalization. This necessary condition leaves the unrestricted odd-covering question open.

The following pages supply the full elementary argument, with the finite Chinese remainder theorem stated as an external input:

  • Lemma 4.1 counts one residue class in a period and derives the density obstruction.
  • Lemma 4.2 reduces possible periods to non-deficient integers. Its non-strict inequality includes perfect numbers; it does not assume that odd perfect numbers do not exist.
  • Lemma 4.3 counts the residues left uncovered by pairwise coprime moduli.
  • Product relaxation handles certificate moduli absent from a proposed covering.
  • Theorem 4.4 bounds the remaining classes' total capacity and yields a contradiction.
  • The complete enumeration checks all 5000 odd positive integers at most 10000 and gives the 23 positive capacity margins. A linked standard-library Python checker makes these arithmetic statements reproducible.
  • Periodicity justifies passing between every integer, one finite period and its quotient.
  • The main theorem composes these deductions.
  • The ideal-language bridge proves the mathematical equivalence with strict ideal covering systems over the integers and identifies the scope of the source's formal translation.

These proofs also explain why finite searches must quantify over all residue assignments and why a failed capacity certificate is not a covering. The prime-factor certificates displayed for 10395, 12285 and 17325 fail; this record does not claim to have ruled out every alternative certificate for them.

Formalization and verification evidence

The public development is centurion at commit b513de2f7b9526e85ea6d760d4415a977f9a2c6b. The recorded toolchain is Lean 4.30.0, with mathlib commit c5ea00351c28e24afc9f0f84379aa41082b1188f. Lean Action CI run 33831024928 reports success at that source commit. The public job metadata records success for the Lean action and the axiom gate. The workflow, gate, audit code and relevant statements were inspected on 2026-09-05; authenticated job logs were unavailable. This is reported public CI evidence, not a locally reproduced Lean build or a line-by-line review of the entire formal development.

The axiom gate restricts reported dependencies to a subset of propext, Classical.choice and Quot.sound. The abstract's wording that all 63 published theorems use exactly those three axioms is stronger than this guarantee: individual theorems may require fewer. The namespace mirror of the upstream covering-system structures is separately qualified on the bridge page; no checked upstream port is claimed.

The local finite arithmetic replay passes. Its mathematical reduction to an assertion about all integer coverings is given on the linked result pages. A successful finite replay and a public Lean build establish different kinds of evidence; neither resolves the unrestricted problem or establishes a new mathematical record.

Bibliographic and background corrections

The canonical preprint has several errors in its background references. These do not enter the elementary finite exclusion proof.

  • Reference [7] misattributes Covering systems with restricted divisibility. It is by Robert D. Hough and Pace P. Nielsen, Duke Mathematical Journal 168 (2019), 3261–3295, DOI 10.1215/00127094-2019-0058. See the canonical source entry. The squarefree-modulus obstruction is proved by Balister, Bollobás, Morris, Sahasrabudhe and Tiba in The Erdős–Selfridge problem with square-free moduli, Algebra & Number Theory 15 (2021), 609–626, DOI 10.2140/ant.2021.15.609. That is a separate source from [6], their paper on the density of the uncovered set; the latter's 2018 preprint announces the squarefree result and defers its proof to the separate paper.
  • Reference [8]'s Setty is Jai Setty, coauthor with Nathan McNew of On the densities of covering numbers and abundant numbers, v2, 10 February 2026. The Mian–Siddique preprint's claim of a complete classification through one million overstates that source. Its Table 1 (p. 22) gives 94 or 95 primitive covering numbers below that endpoint, and Table 2 (p. 23) explicitly leaves 773500 with unknown status. Those pages were checked; the entire McNew–Setty proof and computation have not been replayed here. The pinned centurion README uses a more restrained description.
  • A comment beside capacity_prod_relax reverses the product's direction of change when factors are dropped. The formal inequality has the correct direction; the result page proves and explains it.

Bears on

  • Problem 7: a finite necessary condition and a reusable route from integer coverings to checkable period obstructions.