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  "slug": "davies-levitin-lens-conjecture",
  "title": "A proof of the Davies–Levitin lens conjecture for the indefinite tridiagonal pencil",
  "shortTitle": "The Davies–Levitin lens, for every n",
  "url": "https://evidencepress.org/releases/davies-levitin-lens-conjecture/",
  "oneLine": "A candidate proof that every complex eigenvalue of the Davies–Levitin indefinite tridiagonal pencil lies in the lens where its two Gershgorin disks overlap, for every matrix size.",
  "abstract": "This unrefereed candidate proves Conjecture 5.3 of Davies and Levitin (2014), which implies the closed-disk form of AIM 2015 Problem 11.1. Let H(c) be the 2n×2n symmetric tridiagonal matrix with diagonal c and off-diagonal entries 1, and let S = diag(1,…,1,−1,…,−1) with n entries of each sign. For every n ≥ 1 and real c, every non-real eigenvalue λ of the pencil H(c) − λS satisfies |λ − c| < 2 and |λ + c| < 2, so the non-real spectrum lies in the intersection, not merely the union, of the two Gershgorin disks. The conjecture was previously known for n ≤ 3 and for eigenvalues equidistant from c and −c. A familiar Weyl-function mechanism, applied to the known Chebyshev form of the characteristic equation, reduces it to a new comparison lemma for an explicit sum of Lorentzians centred at the zeros of U(n−1), evaluated at two points of equal height. The lemma is proved by explicit estimates with finitely many Arb-certified constants for n ≥ 8, elementary arguments for n ≤ 2 and, for 3 ≤ n ≤ 7, an explicit estimate combined with a short interval certificate with rational endpoints and Arb ball arithmetic. Certified examples show that the lens fails for some other spectral measures, for a balanced pencil with one weakened coupling, and for unbalanced pencils. The work was produced by an AI research agent and has not been checked by a human specialist.",
  "datePublished": "2026-09-25",
  "dateModified": "2026-09-25",
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    "Anonymous"
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    "detail": "Unrefereed candidate produced by an AI research agent. The theorem rests on a written proof and two short interval-arithmetic certificates. There is no formal verification, independent reproduction or specialist or journal review; asymptotic sharpness of the lens is numerical only; novelty is established only within a bounded literature search."
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      "note": "Public GitHub prerelease v0.1.0-candidate and published Zenodo record (3 files each); every file matched the SHA-256 sums by server checksum and by independent download."
    },
    {
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      "question": "Does the producer’s own pipeline reproduce the stated result from the archived package?",
      "state": "passed",
      "note": "Fresh-extraction replay: manifest; certificates C1 and C2, regression tests and five negative controls in normal and optimised Python; certificate C3 for n ≤ 60; numerical checks.",
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      "dimension": "independentReimplementation",
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      "question": "Has someone else reached the result from an independent implementation?",
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      "question": "Are data and computational environment pinned well enough to rebuild?",
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      "note": "Linux CI (Python 3.12, python-flint 0.9.0) runs the replay; versions are recorded. Typesetting is not pinned."
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    "disclosure": "AI-produced research, computation and drafting. A blind model referee, an independent model re-certification, two refute passes by a different AI model, one commissioned AI-based external review, a producer-coordinated five-role AI editorial gate (Minor Revision) and a two-reviewer AI confirmation round (Accept with minor edits). None of these is specialist or journal peer review."
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  "problem": {
    "name": "Davies–Levitin lens conjecture (Conjecture 5.3; AIM 2015 Problem 11.1)",
    "url": "https://doi.org/10.1016/j.laa.2014.01.025"
  },
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  "keywords": [
    "Davies–Levitin conjecture",
    "Conjecture 5.3 of Davies and Levitin",
    "indefinite linear pencil",
    "non-self-adjoint matrices",
    "non-real eigenvalues",
    "Krein space",
    "indefinite Jacobi matrix",
    "Chebyshev polynomials",
    "Herglotz functions",
    "interval arithmetic"
  ],
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    "For every n ≥ 1 and real c, every non-real eigenvalue λ of the 2n×2n pencil H(c) − λS satisfies |λ − c| < 2 and |λ + c| < 2; hence |Re λ| < 2 − |c| (Theorem 1.1).",
    "A familiar Weyl-function mechanism, applied to the known Chebyshev form, reduces the conjecture to one new comparison lemma, Ψ(x) ≥ Ψ(y) at equal heights, for an explicit Lorentzian sum Ψ over the zeros of U(n−1) (Lemma 3.1); the lemma and its proof are the original contribution.",
    "The comparison lemma is proved by explicit estimates with finitely many Arb-certified constants for n ≥ 8, elementary arguments for n ≤ 2, and a short fail-closed Arb interval certificate for 3 ≤ n ≤ 7 (minimum margin 0.107).",
    "Every non-real eigenvalue off the imaginary axis satisfies the hypothesis of Davies–Levitin's asymptotic Theorem 5.4, and their localisation (50) holds for every n in strict form.",
    "Certified examples show the lens fails for some other spectral measures, for a balanced pencil with one weakened coupling, and for unbalanced pencils m ≠ n (Remark 8.4)."
  ],
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        "title": "A proof of the Davies–Levitin lens conjecture for the indefinite tridiagonal pencil"
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        "date": "2026-09-25",
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        "publicUrl": "https://github.com/ipitchford/davies-levitin-lens-conjecture/blob/v0.1.0-candidate/review/EDITORIAL_DECISION.md",
        "publicSummary": "Five roles reviewed one frozen target (all Minor Revision; no error found in the proof). All 51 items were answered in one repair batch; 50 were made and one journal-version note was deferred. Material repairs added certified counterexamples for unbalanced pencils and a weakened coupling, reframed the reduction as a known mechanism, and hardened the essential certificates. Two confirmation reviewers accepted the repairs with minor edits, which were applied."
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    "Replace the interval certificate for 3 ≤ n ≤ 7 by a short elementary inequality.",
    "Prove the observed 2/3 slack in the comparison lemma and the asymptotic sharpness of the lens.",
    "Find the correct localisation for unbalanced pencils m ≠ n and other Jacobi blocks, where the lens itself fails (Remark 8.4)."
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    {
      "citation": "Davies and Levitin (2014): spectra of a class of non-self-adjoint matrices; Conjecture 5.3 and Theorems 2.3, 3.3 and 5.4.",
      "url": "https://doi.org/10.1016/j.laa.2014.01.025",
      "doi": "10.1016/j.laa.2014.01.025"
    },
    {
      "citation": "Öztürk (2023): the conjecture for n ≤ 3 and for eigenvalues equidistant from c and −c; the Chebyshev statement (Remark 1.2).",
      "url": "https://doi.org/10.1002/mma.8766",
      "doi": "10.1002/mma.8766"
    },
    {
      "citation": "Levitin and Öztürk (2018): an associated two-parameter eigenvalue problem.",
      "url": "https://doi.org/10.1007/978-3-319-75996-8_19",
      "doi": "10.1007/978-3-319-75996-8_19"
    },
    {
      "citation": "American Institute of Mathematics (2015): open problems from the workshop Mathematical aspects of physics with non-self-adjoint operators, Problem 11.1.",
      "url": "https://aimath.org/pastworkshops/nonselfadjointproblems.pdf",
      "doi": null
    }
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