Pith Number

pith:IERT623X

pith:2008:IERT623XDDYB3QMO3SFQMOMARP

not attested not anchored not stored refs pending

On finite-index extensions of subgroups of free groups

Pascal Weil (LaBRI), Pedro Silva (CMUP)

arxiv:0808.2381 v2 · 2008-08-18 · math.GR

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

Add to your LaTeX paper

\usepackage{pith}
\pithnumber{IERT623XDDYB3QMO3SFQMOMARP}

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	2026-05-18T00:17:46.789175Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

41233f6b7718f01dc18edc8b0639808bd49c23afcba56da040ca0a5b4d4fd34f

Aliases

arxiv: 0808.2381 · arxiv_version: 0808.2381v2 · doi: 10.48550/arxiv.0808.2381 · pith_short_12: IERT623XDDYB · pith_short_16: IERT623XDDYB3QMO · pith_short_8: IERT623X

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/IERT623XDDYB3QMO3SFQMOMARP \
  | 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: 41233f6b7718f01dc18edc8b0639808bd49c23afcba56da040ca0a5b4d4fd34f

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "7d1fa3fe6bdfab36e60ebcdf93ede742a9a4d91893d7f2354ba4f12165b08561",
    "cross_cats_sorted": [],
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "primary_cat": "math.GR",
    "submitted_at": "2008-08-18T12:43:02Z",
    "title_canon_sha256": "34dc815e980a4d7d445ad9ca064878a61b861bbc963381cf944c40125ae408a1"
  },
  "schema_version": "1.0",
  "source": {
    "id": "0808.2381",
    "kind": "arxiv",
    "version": 2
  }
}