README.md

metadata

license: cc0-1.0
task_categories:
  - text-classification
  - text-generation
language:
  - en
size_categories:
  - 1K<n<10K
tags:
  - provenance
  - low-background
  - data-curation
  - dataset-contamination
  - dendro
configs:
  - config_name: default
    data_files:
      - split: train
        path: data/train-*

Dendro low-background corpus

5034 arXiv records annotated with archival evidence of when they existed, produced by Dendro v0.1.0.

2500 of them (49.7%) are low-background: an independent registration record places them before 2021-01-01, i.e. before large-scale text generation. The name is from metallurgy — low-background steel is steel smelted before the 1945 atmospheric tests: not special steel, just ordinary steel that happens to predate the contamination, and valuable because no amount of later care can reproduce it.

Read this before you use it

• This is not an AI-writing detector, and these columns must not be used as one. They report evidence that content existed before a date. Nothing here supports a conclusion that a particular person did or did not write something.
• Absence of evidence is not evidence. Most text that has ever existed was never archived. dendro_abstained marks rows where the evidence is too thin to act on — those are unknown, not generated.
• Every row is witnessed by arXiv and arXiv alone. dendro_operators is 1 throughout, and dendro_flags contains single_operator. Compromising one organisation would be sufficient to move every date in this dataset. Dendro's whole argument is that confidence should come from independent operators; this corpus has one, and the column says so rather than hiding it.
• The recent split is "human-attributed", not "verified human". By 2025 an unknown share of abstracts have been through a model. There is no clean recent human corpus to be had — which is the argument for dating by archive rather than by inspection.
• Selection is not neutral. Archived text over-represents what crawlers reached: English, institutional, indexed, long-lived. A low-background subset concentrates every one of those biases.

Columns

column	meaning
text	title + abstract, as fingerprinted
title, doi	the record's own metadata
url, arxiv_id, category, era	identifiers and provenance of the record
published	arXiv v1 submission date — the witness
dendro_not_after	date the content is proven to have existed by
dendro_not_after_year	integer year, convenient for filtering
dendro_human_origin_p	calibrated probability — not a label
dendro_ci_low / dendro_ci_high	90% credible interval, the honest width of the claim
dendro_abstained	true when the evidence is too thin to act on
dendro_operators	count of independent operators behind the bound
dendro_evidence_logodds	how hard the bound would be to forge
dendro_flags	detected inconsistencies
dendro_explanation	human-readable receipt naming the witness sources
low_background	proven pre-2021 existence and dendro_ci_low ≥ 0.8

Why the threshold is 0.8 and not 0.95

Because that is what the evidence in this corpus can actually support, and moving the threshold to flatter the number would be the whole problem with provenance tooling.

Every row here rests on one operator. Under Dendro's model a single arXiv registration gives an evidence log-odds of ~6.5, which puts the lower end of the 90% credible interval at about 0.85 no matter how trustworthy arXiv is — the interval is wide because corroboration is absent, not because the record is doubtful. At ci_low ≥ 0.90 this dataset would contain zero low-background rows, which is a true statement about single-operator evidence and a useless artefact.

So the flag is set where single-operator registration evidence genuinely reaches, and the number that would tighten it is dendro_operators — not the threshold. A document witnessed by arXiv and the Internet Archive and Common Crawl clears 0.95 comfortably; filter on dendro_ci_low yourself if you want a different line.

There is deliberately no is_synthetic column and no boolean verdict. Code that wants a filter must pick a threshold explicitly, and should prefer dendro_ci_low so the choice is conservative.

Three lines to use it

from datasets import load_dataset
ds = load_dataset("NagaYu/dendro-lowbackground", split="train")
clean = ds.filter(lambda r: r["low_background"])          # 2500 rows

Purity / retention trade-off

Selecting to bound the expected synthetic fraction (provably maximum-cardinality — see dendro.corpus_report.build_low_background_subset):

max expected synthetic	rows kept	retention
≤ 1%	0	0.0%
≤ 2%	0	0.0%
≤ 5%	0	0.0%
≤ 10%	0	0.0%
≤ 20%	2790	55.4%

Method, in one paragraph

Dendro asks independent archives — the Internet Archive, Common Crawl, arXiv, Crossref, public posting archives — what they observed and when, groups witnesses by operator rather than by count (twenty captures from one archive are one archive), and reports the earliest time whose surviving evidence clears a failure-probability budget. It never reads the prose, which is why its accuracy does not move when a new generator ships. Probabilities are produced by a mixture that collapses to the base rate when evidence is absent, so "no evidence" cannot be reported as "synthetic".

The calibrator is left unfitted here on purpose: a fitted map encodes the base rate of the corpus it was fitted on, and baking that into a published artefact would make every row depend on a split nobody downstream can inspect. These are the raw numbers.

Provenance of the data itself

arXiv metadata, including abstracts, is offered under CC0 1.0 through the public API and OAI-PMH, which is how it was harvested. Thank you to arXiv for use of its open access interoperability.

Generated 2026-08-10 by scripts/publish_dataset.py · Apache-2.0 code, CC0 data.