Pith Number

pith:R2UMOGL2

pith:2018:R2UMOGL2LF5Z4Q7EWH46SLYB6H

not attested not anchored not stored refs pending

Proving that a Tree Language is not First-Order Definable

Martin Beaudry

arxiv:1812.01674 v1 · 2018-12-04 · cs.FL · cs.LO

Open paper page JSON Open Graph Bundle Merged state Verified badge What is a Pith Number?

Add to your LaTeX paper

\usepackage{pith}
\pithnumber{R2UMOGL2LF5Z4Q7EWH46SLYB6H}

Prints a linked badge after your title and injects PDF metadata. Compiles on arXiv. Learn more · Embed verified badge

Record completeness

1 Bitcoin timestamp

2 Internet Archive

3 Author claim open · sign in to claim

4 Citations open

5 Replications open

✓ Portable graph bundle live · download bundle · merged state

The bundle contains the canonical record plus signed events. A mirror can host it anywhere and recompute the same current state with the deterministic merge algorithm.

Receipt and verification

First computed	2026-05-17T23:59:00.931584Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

8ea8c7197a597b9e43e4b1f9e92f01f1cb18be784dbfe2e0e76185f876c88326

Aliases

arxiv: 1812.01674 · arxiv_version: 1812.01674v1 · doi: 10.48550/arxiv.1812.01674 · pith_short_12: R2UMOGL2LF5Z · pith_short_16: R2UMOGL2LF5Z4Q7E · pith_short_8: R2UMOGL2

Agent API

Resolver JSON Graph JSON Events JSON Schema Signing key

Verify this Pith Number yourself

curl -sH 'Accept: application/ld+json' https://pith.science/pith/R2UMOGL2LF5Z4Q7EWH46SLYB6H \
  | jq -c '.canonical_record' \
  | python3 -c "import sys,json,hashlib; b=json.dumps(json.loads(sys.stdin.read()), sort_keys=True, separators=(',',':'), ensure_ascii=False).encode(); print(hashlib.sha256(b).hexdigest())"
# expect: 8ea8c7197a597b9e43e4b1f9e92f01f1cb18be784dbfe2e0e76185f876c88326

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "597523744ca8835fbc7a132d0f9f52aba90d91f3936122f781225e8452404115",
    "cross_cats_sorted": [
      "cs.LO"
    ],
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "primary_cat": "cs.FL",
    "submitted_at": "2018-12-04T20:45:43Z",
    "title_canon_sha256": "84f9036a8bfb9e75293d9da54d5e48988f1fc9c8e2221c95ee880196f8b6e280"
  },
  "schema_version": "1.0",
  "source": {
    "id": "1812.01674",
    "kind": "arxiv",
    "version": 1
  }
}