Pith Number

pith:HZLVOKH7

pith:2026:HZLVOKH7EAK254VOF576YYGXW7

not attested not anchored not stored refs pending

Copy-as-Decode: Grammar-Constrained Parallel Prefill for LLM Editing

Ziyang Liu

Copy-as-Decode recasts LLM editing as grammar-constrained decoding that copies input spans via single-step parallel prefill instead of full autoregressive regeneration.

arxiv:2604.18170 v2 · 2026-04-20 · cs.CL · cs.AI

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\usepackage{pith}
\pithnumber{HZLVOKH7EAK254VOF576YYGXW7}

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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.

Claims

C1strongest claim

Composed with the empirical kernel over each corpus's span histogram this yields a closed-form wall-clock bound of 29.0× / 3.4× / 4.2× (13.0× pooled). A token-level extension reaches 91–99% coverage with 4.5×–6.5× floors. Oracle programs round-trip through the deterministic resolver on all 482 cases.

C2weakest assumption

That accurate copy spans (line ranges or token ranges) can be selected at inference time; the mechanism itself is shown to be lossless under perfect spans, but the perturbation study demonstrates that off-by-one noise drops pooled EM from 100% to 15.48%.

C3one line summary

Copy-as-Decode recasts LLM editing as grammar-constrained decoding over copy and generate primitives, delivering closed-form upper-bound speedups of 13x pooled on editing benchmarks via parallel prefill without any training.

Receipt and verification

First computed	2026-05-26T01:03:30.635377Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

3e575728ff2015aef2ae2f7fec60d7b7ee979e05424cc372baf19e2173d4b17d

Aliases

arxiv: 2604.18170 · arxiv_version: 2604.18170v2 · doi: 10.48550/arxiv.2604.18170 · pith_short_12: HZLVOKH7EAK2 · pith_short_16: HZLVOKH7EAK254VO · pith_short_8: HZLVOKH7

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/HZLVOKH7EAK254VOF576YYGXW7 \
  | 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: 3e575728ff2015aef2ae2f7fec60d7b7ee979e05424cc372baf19e2173d4b17d

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "17efdecb043b41135baa5d878e21bba3cc2c4eb3506bb483e6ebee44fb024037",
    "cross_cats_sorted": [
      "cs.AI"
    ],
    "license": "http://creativecommons.org/licenses/by/4.0/",
    "primary_cat": "cs.CL",
    "submitted_at": "2026-04-20T12:29:53Z",
    "title_canon_sha256": "9b4be4b275a6cf057ef9a4ec5952bbc2cc1c7a90023db06737844ca715b4c59c"
  },
  "schema_version": "1.0",
  "source": {
    "id": "2604.18170",
    "kind": "arxiv",
    "version": 2
  }
}