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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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JenW1N: Lean proof of Problem 354 part (i), Conjectures.io record 815c1d5f

../

evidence/: Retains the site's solution file Main.lean as fetched on 2026-09-28, the bytes the site's kernel accepted, unedited and not built here.

jenw1n_2026_erdos_354_part_i_lean_proof: Record identity, the site's dates and review decision, its verification report, the task's pinned statement and the public standing of the result as of 2026-09-28.

target: The accepted theorem: the catalog statement of the first question of Problem 354 with its answer instantiated to true, unfolded to the site's wording, with the proof's reduction chain.


JenW1N (the solver handle the bounty site credits), Erdős problem 354 - part i, Lean 4 proof accepted by the bounty site Conjectures.io, record 815c1d5f-3afb-4430-8e2c-260d9038f5b0 (https://conjectures.io/results/815c1d5f-3afb-4430-8e2c-260d9038f5b0), attacked as Prove: Lean verification 11 September 2026, review approval 15 September 2026 under the site's manual-review policy v3, certification 16 September 2026, bounty paid. Conjectures.io is a Bittensor subnet that publishes Erdős problems as Lean statements pinned to a commit of the formal-conjectures catalog and pays for kernel-checked proofs accepted in its review.

The folder holds no folder-name PDF: the source is the Lean file the site's record publishes, with no write-up, so the folder-name Markdown file source record is the source itself and records the URLs, the verified statement, the site's dates, its review decision and verification report, and the public standing of the result (the library's no-PDF shape). The Lean file is retained unedited under evidence/assets/solution_815c1d5f/Main.lean; the file's header declares no author and no AI system.

Provenance of the proof file. https://conjectures.io/results/815c1d5f-3afb-4430-8e2c-260d9038f5b0/solution/download (the page .../solution shows the first 500 of its lines), fetched (HTTP 200); 485,414 bytes, 10,152 lines; two other fetches on the same day (02:41 and 03:49 UTC) returned identical bytes. Header: "A proof of the full Erdős 354(levelIndex) proposition" (the "(levelIndex)" is a mechanical rename of an identifier i). The file is 130 sections, each headed /- Source: <name>.lean -/, from DigitTransport.lean to FullTarget.lean, all in the namespace Erdos354Formal, with the final theorem target at line 10148.

Read status: claims checked. The final theorem was read against the site's printed type, the task bundle's metadata and the catalog file, and its reduction chain to two criteria on binary digits was read (result page). The mathematical core (about 9,000 lines: a joining and disjointness argument on the binary digit sequences of α\alpha and β\beta through empirical measures, tower shift spaces and L2L^2 rigidity) was not read line by line, and the file was not built here, so the kernel check is the site's, on a single kernel. No proof was verified here and no kernel credit is claimed.

Bears on. Problem 354: the status-defining source for the first question (base 22), answered yes exactly in the site's formulation; the second question (a base γ∈(1,2)\gamma\in(1,2)), strong completeness and the set-union reading are untouched.

The verified statement

The record page, the task page and the task bundle's source-metadata.json print the target type

lean
True ↔ ∀ α > 0, ∀ β > 0, Irrational (α / β) →
  IsAddCompleteNatSeq' (Erdos354.FloorMultiples.interleave α β 2)

which is Erdos354.erdos_354.parts.i of FormalConjectures/ErdosProblems/354.lean with answer(sorry) instantiated to True, at the pinned catalog commits 8432eac9 (record page) and 6a786f99 (task bundle), both with the same source type SHA-256. Neither pinned commit is reachable on GitHub; the catalog's default branch, prints the same statement and docstring. In the catalog, FloorMultiples a γ n is ⌊γna⌋∈Z\lfloor\gamma^na\rfloor\in\mathbb Z, interleave a b γ n is FloorMultiples a γ (n / 2) for even nn and FloorMultiples b γ (n / 2) for odd nn, subseqSums' A is the set of sums ∑i∈BA(i)\sum_{i\in B}A(i) over finite index sets BB, and IsAddCompleteNatSeq' A says every sufficiently large integer lies in subseqSums' A. So the theorem says: for all α,β>0\alpha,\beta>0 with α/β\alpha/\beta irrational, every sufficiently large integer is ∑s∈S⌊2sα⌋+∑t∈T⌊2tβ⌋\sum_{s\in S}\lfloor2^s\alpha\rfloor+\sum_{t\in T}\lfloor2^t\beta\rfloor for some finite S,T⊂NS,T\subset\mathbb N, each index used at most once and equal values at different indices counted separately, which is the site's "That is" clause read clause for clause (the result page gives the correspondence). The proof's own lemmas interleave_even and interleave_odd (lines 268--274) unfold the catalog's interleave by simp into the two floor sequences; they compile only against the corrected n / 2 form of the definition (PR #1330, 3 December 2025), so the kernel acceptance itself shows the pinned definition is the corrected one, which the type hash alone (naming the constant, not its body) would not.

Acceptance shown on the results page

The record page, shows Lean verification Passed (verified; the review text dates the acceptance to 20:48:55 UTC that day), Conjectures review Approved (REVIEW_APPROVED under manual-review policy v3, decided 15 September 2026), Reward Paid and Certified 16 September 2026; checked in 3 min 3 s in a Landrun-with-seccomp sandbox by validator-428166381eba73ec1c61148f6d74866b74145563. The verification report lists a static scan ("no imports, no axiom declarations, no sorry, no native_decide, no unsafe options"), Challenge built, source type hash matches, Solution built, "Statement unchanged" ("exactly the same canonical type as the task's target - it was not weakened or restated"), "Only permitted axioms" (propext, Quot.sound, Classical.choice), "Lean kernel accepted" and the second kernel "Not run" ("The verdict rests on a single kernel implementation"). The review note says the submission "proves the affirmative answer to Erdős Problem 354(i)", that "The accepted Lean statement preserves the intended multiset interpretation and includes every exponent", that no qualifying earlier public solution was found (the part (ii) formalization "uses a base below 2 and does not prove part (i)"; "Fan's September 2026 completeness criterion leaves the relevant two-ray case unresolved"; the full proof claim posted on 13 September, with a repository created 12 September, "is later than acceptance"), and that these findings "are not a guarantee of absolute novelty". The accepting body is the bounty site alone: no refereed publication, no write-up, no erdosproblems.com acceptance and no formal-conjectures catalog agreement was found on 2026-09-28; the catalog's default branch keeps both parts research open.

Route of the proof file

The final theorem target : fcTypeOfName% "Erdos354.erdos_354.parts.i" (line 10148) closes by exact full_target_of_symbolic_digit_criteria applied to symbolicallyDisjoint_of_boundedZeroRuns (line 8921) and forwardTransport_of_not_symbolicallyDisjoint (line 10122). Its chain:

  • full_target_of_normalized (line 346) reduces α,β>0\alpha,\beta>0 to α,β≥1\alpha,\beta\ge1: exists_common_scale (line 337) picks NN with 2Nα,2Nβ≥12^N\alpha,2^N\beta\ge1 and complete_of_dyadic_scale (line 329) pulls completeness back along the injective index shift n↦2N+nn\mapsto2N+n; pair_sum_mem_subseqSums (line 276) maps a pair of finite index sets to one index set of the interleaving.
  • full_target_of_dynamical_criteria (line 402) derives the target from a symmetric relation DD on pairs and three inputs: DD implies the completeness of the pair for α,β≥1\alpha,\beta\ge1; bounded zero runs in the binary digits of α\alpha imply DD; and when α\alpha has unboundedly many ones and DD fails, ones of α\alpha are transported forward into ones of β\beta at a positive offset.
  • full_target_of_symbolic_digit_criteria (line 1118) instantiates DD with SymbolicallyDisjoint (line 1084) through completePair_of_symbolicallyDisjoint (line 1102).
  • The two criteria fill the rest of the file: carry combinatorics and transport for the bounded-zero-runs case, and, for the transport case, a joining argument on the shift spaces of the digit sequences through empirical measures, tower alphabets and an L2L^2 rigidity exclusion (cross_marked_rigidity_exclusion). Not read line by line here.

A text scan of the file found 601 theorem or lemma declarations and 91 def lines at column zero, six abbrevs and one inductive (HasCarryPairCount, line 6928), all inside Erdos354Formal; open commands naming only Filter, MeasureTheory, Topology, TopologicalSpace and the scoped ENNReal; no sorry, axiom, native_decide, unsafe, set_option, implemented_by, extern, opaque or _root_; no instance, notation, macro, elab or syntax; no partial definition (the textual hits of partial are identifiers and comments); decide only as a classical decidability term (line 919) and on finite Bool lemmas (lines 1142--1164, 1334, 1352); and no redefinition of FloorMultiples, interleave, subseqSums' or IsAddCompleteNatSeq'. The site's static scan reports no imports in the submitted source: the imports and the namespace Bounty wrapper are supplied by the task's trusted header.

Neighbors

The later manuscript claiming the stronger strong-completeness statement is filed at yu_chen_2026_erdos_problem_354_i_strong_completeness_two_dyadic_floor_sequences (unreviewed; the site's review notes it as later than acceptance). The part (ii) Lean proof the review mentions is kitamura_2026_lean_proof_erdos_problem_354_ii, and Fan's criterion is fan_2026_strongly_complete_sets_conjecture_erdos; the problem's origin is Question 12 of Graham's 1971 survey.