Pith Number

pith:4PJEJF4Y

pith:2009:4PJEJF4YS4AILL7NHOWKA6F4BQ

not attested not anchored not stored refs pending

Projections and idempotents with fixed diagonal and the homotopy problem for unit tight frames

David Larson, James E. Tener, Julien Giol, Leonid V. Kovalev, Nga Nguyen

arxiv:0906.0139 v2 · 2009-05-31 · math.FA

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

Add to your LaTeX paper

\usepackage{pith}
\pithnumber{4PJEJF4YS4AILL7NHOWKA6F4BQ}

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	2026-05-18T04:27:28.354672Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

e3d2449798970085afed3baca078bc0c363ca37a35f7b0c1ffe118c120a20943

Aliases

arxiv: 0906.0139 · arxiv_version: 0906.0139v2 · doi: 10.48550/arxiv.0906.0139 · pith_short_12: 4PJEJF4YS4AI · pith_short_16: 4PJEJF4YS4AILL7N · pith_short_8: 4PJEJF4Y

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/4PJEJF4YS4AILL7NHOWKA6F4BQ \
  | 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: e3d2449798970085afed3baca078bc0c363ca37a35f7b0c1ffe118c120a20943

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "8b67a587e50c7cfdf08f31df5db863e1560193123d75fa67514445d71df65e77",
    "cross_cats_sorted": [],
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "primary_cat": "math.FA",
    "submitted_at": "2009-05-31T08:13:50Z",
    "title_canon_sha256": "0d97aca1ba5f48d00c89aa50e32ca6efd504e86eae56b39695f98161d6512341"
  },
  "schema_version": "1.0",
  "source": {
    "id": "0906.0139",
    "kind": "arxiv",
    "version": 2
  }
}