check-hallucinations

A command-line tool to detect hallucinated references in BibTeX files before submitting a paper to arXiv.

It looks up each reference (Semantic Scholar, then OpenAlex when Semantic Scholar has no matching title; arXiv; the web page of a @misc), and checks that the paper found is the one the entry describes: same title, same authors, same year, and a DOI that resolves to that title.

Titles are compared whatever their punctuation and markup: &, #, +, %, ?, :, parentheses, quotes, dashes, LaTeX accents and commands (D\&C, C\#, Bissyand{\'e}, \emph{x}), and venue names that some records prefix to the title. Symbols that change the meaning stay: C, C++ and C# are different titles.

Installation

pip install check-hallucinations

Usage

check-hallucinations references.bib            # silent when every entry is confirmed
check-hallucinations --json references.bib     # findings as a JSON array, [] when clean
check-hallucinations -v references.bib         # also list each confirmed entry with its URL

One line per finding, file:line: rule: key: message:

references.bib:5: authors-mismatch: wrongauthors: first author smith is not an author; the paper is by Ashish Vaswani, Noam Shazeer, N. Parmar, J. Uszkoreit, ...
references.bib:5: year-mismatch: wrongauthors: year 2009, but the paper is from 2017
references.bib:9: doi-mismatch: wrongdoi: doi 10.1038/nature14539 is 'Deep learning'
references.bib:13: not-found: fake: not found in SemanticScholar: A Unified Theory of Self-Healing Compilers for Quantum Blockchains

Exit status: 0 every entry confirmed, 1 findings, 2 the file cannot be read. This makes it usable as a CI step.

Rules

• not-found, title-mismatch: no paper with this title (the closest title is given).
• authors-mismatch: the first author is not an author of the paper found, or fewer than half of the authors are. Last names are compared, LaTeX accents and diacritics removed; and others is ignored.
• year-mismatch: the year differs from the paper's by more than two (preprint, online-first and issue years differ, and Semantic Scholar may date a later version).
• doi-not-found, doi-mismatch: the doi field does not exist, or resolves (doi.org, Crossref and DataCite) to another title.
• arxiv-not-found, arxiv-mismatch: an arXiv @misc whose identifier does not exist or has another title.
• web-mismatch, web-not-found, no-url: a web @misc whose page has another title, is gone, or has no URL in howpublished.
• no-title, unparsed: an entry without title, a block that is not valid BibTeX.
• unchecked: a lookup failed (network, rate limit). The entry is neither confirmed nor refuted; run again.

misc entries with an arXiv identifier are checked on arXiv, other misc entries on their web page.

API key

By default the tool uses the public Semantic Scholar API (rate-limited). For higher throughput, set the SEMANTICSCHOLAR_API_KEY environment variable (or store it with keyring set check-hallucinations ss_api_key):

export SEMANTICSCHOLAR_API_KEY=your-key-here
check-hallucinations references.bib

Answers are cached in ~/.cache/check-hallucinations.

Library

process_bibtex_file(path) prints the per-entry report of earlier versions (now with author, year and DOI mismatches as extra lines); check_entry(entry) returns the findings of one parsed entry.

Development

uv venv && uv pip install -e '.[dev]'
.venv/bin/pytest && .venv/bin/ruff check . && .venv/bin/mypy check_hallucinations tests scripts
.venv/bin/python scripts/live_check.py [more-real.bib ...]   # network: silent when the lookup is right

The live check runs the lookup on scripts/corpus/real/ (real papers with difficult titles: every entry must be confirmed) and scripts/corpus/invented/ (every entry must be reported). Add a title that the tool gets wrong to the corpus before fixing it.

License

MIT