A finite check of the Murty-Simon lemmas of Das-Fox on all diameter-2-critical graphs with at most 11 vertices (a sanity check of claims by others)

Das and Fox (arXiv:2610.39032, 28 Oct 2026, unrefereed) claim a proof of the Murty-Simon conjecture: a diameter-2-critical (D2C) graph on n vertices has at most floor(n2/4) edges. Two of their lemmas are unconditional statements about all D2C graphs: Lemma 1.2 (for every maximal matching M, |E \ M| is at most the number of non-edges) and Lemma 1.3 (if equality holds for every maximal matching, the graph is triangle-free). The proof is theirs. This is a finite sanity check of claims by others; we claim nothing new and do not verify the proof. What was checked (Tier C: exact integer arithmetic, two independent implementations). All 4,419 D2C graphs with 3 ≤ n ≤ 11 (counts 1, 2, 3, 5, 10, 30, 103, 519, 3746) and all 776,217 of their maximal matchings: 0 violations of Lemma 1.2, Lemma 1.3 or Theorem 1.1. The maximum number of edges floor(n2/4) is attained uniquely by the balanced complete bipartite graph. Exactly one graph per n is an equality case for all maximal matchings (balanced Ka,b, triangle-free), so Lemma 1.3 is nearly vacuous in this range; D2C graphs with a triangle stay below the bound of Lemma 1.2 by at least 1 at n = 6 and at least 10 at n = 11. The counts equal OEIS A330333, so the census is a recomputation, and Theorem 1.1 was already reported proved for n ≤ 24 and n = 26 (Fan 1987, as reported by Dailly-Foucaud-Hansberg). Audit. A separate AI agent instance (not a human) reproduced the census with its own Rust code, including a fresh enumeration of all 1,006,700,565 connected graphs on 11 vertices (ACCEPT_WITH_CORRECTIONS; eight corrections applied). Limitations. The Das-Fox proof is not verified; the intermediate lemmas 2.4, 2.5, 2.13, 3.1, 3.2 were checked by the producer only; nothing is claimed for n ≥ 12; the preregistration was committed together with the results (self-attested); no Lean; no human audit. The paper's full text is third-party and is not redistributed.