23 of 107 blocks of the round 4 manuscript are new or changed since round 3; 20 of 104 blocks of round 3 no longer appear. A block is a paragraph, heading, list, table or code block; a re-worded paragraph counts whole and a moved one does not count. This compares the two submitted texts and is not the response letter.
New or changed blocks
[under "Abstract"]
Agents4Science 2025 was the first conference to require an AI system as the first author of every submission and to review every complete submission with three large-language-model (LLM) reviewers. Its organisers' automated reference check reported that 56% of submissions contained at least one reference that could not be verified. We re-examined all 6,849 references in the 304 submissions with a parsable reference list, using a reproducible verification pipeline (DOI, arXiv and URL resolution; Crossref, OpenAlex, Semantic Scholar, OpenLibrary and Google Books) followed by manual adjudication of every reference it could not verify (857 decisions, each with logged evidence) under a protocol fixed before adjudication began. The labels were validated blind by independent agent instances (150 re-adjudicated decisions: category agreement 83%, kappa 0.75; fabricated-versus-not 92%, kappa 0.83) and by a human coder on 64 items; among 180 automatically verified entries, about 8% were real works cited with a wrong author list, venue or identifier and about 2% did not exist, so every adjudicated rate below is a lower bound. Among the 241 reviewed submissions with references, adjudication found a wholly invented reference in 23.7% (95% CI 18.7-29.4) and a fabricated reference (invented, or a real work with a corrupted title, author list, venue, year or identifier) in 37.8% (31.9-44.0); 3.8% of their 5,230 references were invented and 7.2% fabricated, rising to an estimated 6.2% (4.8-8.8) and 15.2% (12.1-19.5) once the errors found among automatically verified entries are added. Accepted papers cite fewer: no invented reference was detected among their 1,308 references (an estimated 34, 14-69, would be expected undetected) and nine corrupted ones were detected in eight of 48 papers, with an adjusted fabricated share of 9.3% (6.0-13.8) against 17.2% for rejected submissions. The organisers' flag was a screen, not a measure: 51.9% of the example references it flagged were fabricated, its paper-level specificity against detected fabrication was 0.66 (sensitivity 0.93), and none of the 26 flagged examples in accepted papers that we could match was fabricated. Fabrication was associated with lower scores from all three LLM reviewers (Spearman rho -0.13 to -0.15 for the fabricated share, -0.18 to -0.21 for the invented share), with lower human expert scores (rho -0.28 and -0.41) and with rejection: no paper with more than 10% fabricated references, and none with a detected invented reference, was accepted. Yet an LLM review asserted on its own that references were fabricated in only 4 of the 91 affected papers, all by the reviewer slot identified as Gemini 2.5 Pro, and no human expert review did. Of the 513 detected fabricated references, 56% were invented and 44% were corrupted real works; 32 invented references carried a DOI or arXiv identifier. All code, cached API responses, adjudication logs, blind-validation files and the human-coded sheet are public.
[under "2. Related work"]
**Prevalence in the human-authored literature.** Zhao et al. [2026] audit 111 million references in 2.5 million papers
across arXiv, bioRxiv, SSRN and PubMed Central and document a sharp post-2023 rise in non-existent references,
concentrated in fields with rapid AI uptake and in manuscripts with linguistic signatures of AI-assisted writing.
Topaz et al. [2026] audit 2.5 million biomedical papers and report a twelve-fold increase in two years, from one
fabricated reference per 2,828 papers in 2023 to one per 277 in early 2026. Xu et al. [2026] (GhostCite) verify 2.2
million citations from 56,381 papers at AI/ML and security venues and find that 1.07% of papers contain invalid
citations, with an 80.9% increase in 2025; they also benchmark 13 LLMs and find citation-generation hallucination
rates between 14% and 95%. Ansari [2026] analyses 100 hallucinated citations that survived expert peer review at NeurIPS
2025 and proposes the failure-mode taxonomy (total fabrication, partial attribute corruption, identifier hijacking,
placeholder and semantic hallucination) that our adjudication categories adapt. Russinovich et al. [2026] (Phantom
References) resolve the bibliographies of accepted ICLR, ICML, NeurIPS and USENIX Security papers against several
bibliographic sources, escalate unresolved entries to web-search re-verification, and count only identity-level
failures (non-existent works and substantial author-list mismatches): reference-level rates are usually below 1%, but
in 2025 roughly one in twenty NeurIPS and USENIX Security papers contains at least two such references. Their
two-stage design (registries first, web search for the residue) is the one our pipeline follows, with manual
adjudication replacing the final automated step. Shi et al. [2026] (CiteAudit) decompose citation checking into
metadata extraction, memory lookup, web retrieval and a final judgement by cooperating agents, and release a
human-validated benchmark on which their pipeline outperforms single LLMs and commercial checkers; our automated stage
is a deterministic, cached version of the same decomposition; our blind re-adjudication is an agent-level analogue of
their human validation, not a substitute for it (Sections 5.1 and 7).
[under "4. Methods"] [block of 1808 characters not shown; it begins "**Reliability of the labels.** Two blind checks were added in revision. (i) A se…"]
[under "4. Methods"] [block of 3577 characters not shown; it begins "**Analysis.** All analyses were pre-specified (paper/analysis_plan.md in the rep…"]
[under "5.1 Corpus and parsing yield"] [block of 1774 characters not shown; it begins "**Parser recall.** For the 218 submissions with bracket-numbered lists, the rati…"]
[under "5.1 Corpus and parsing yield"] [block of 1742 characters not shown; it begins "**Reliability of the labels.** On the 150 blind re-adjudicated decisions the two…"]
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