Pith Number

pith:UP7WBPUX

pith:2026:UP7WBPUX2CQAMH4P73KNXMGHMF

not attested not anchored not stored refs pending

SMolLM: Small Language Models Learn Small Molecular Grammar

Akhil Jindal, Harang Ju

A 53K-parameter transformer generates valid SMILES by resolving constraints in fixed order: brackets first, rings second, valence last.

arxiv:2605.06322 v2 · 2026-05-07 · cs.LG

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\pithnumber{UP7WBPUX2CQAMH4P73KNXMGHMF}

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Record completeness

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2 Internet Archive

3 Author claim open · sign in to claim

4 Citations open

5 Replications open

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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

the same block resolves SMILES constraints across passes in a fixed order: brackets first, rings second, and valence last, as shown by error classification, linear probing, and sparse autoencoders. A systematic ablation across attention heads and passes further localizes the first bracket-matching step to a single attention head.

C2weakest assumption

That linear probing, sparse autoencoders, and error classification reveal the actual causal computation rather than surface correlations, and that high validity on the benchmark reflects genuine grammar learning instead of dataset-specific pattern matching.

C3one line summary

A 53K-parameter model generates 95% valid SMILES on ZINC-250K, outperforming larger models, by resolving chemical constraints in fixed order: brackets first, rings second, valence last.

Receipt and verification

First computed	2026-05-29T01:04:37.579711Z
Builder	pith-number-builder-2026-05-17-v1
Signature	Pith Ed25519 (`pith-v1-2026-05`) · public key
Schema	pith-number/v1.0

Canonical hash

a3ff60be97d0a0061f8ffed4dbb0c7615c503b048727f55fdc38c17610cdc4f0

Aliases

arxiv: 2605.06322 · arxiv_version: 2605.06322v2 · doi: 10.48550/arxiv.2605.06322 · pith_short_12: UP7WBPUX2CQA · pith_short_16: UP7WBPUX2CQAMH4P · pith_short_8: UP7WBPUX

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/UP7WBPUX2CQAMH4P73KNXMGHMF \
  | 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: a3ff60be97d0a0061f8ffed4dbb0c7615c503b048727f55fdc38c17610cdc4f0

Canonical record JSON

{
  "metadata": {
    "abstract_canon_sha256": "f906cd36d6791d7e91c9eae6e3e7c4a7664a8909544df1b45fecd4d6a4c818a9",
    "cross_cats_sorted": [],
    "license": "http://creativecommons.org/licenses/by/4.0/",
    "primary_cat": "cs.LG",
    "submitted_at": "2026-05-07T14:21:26Z",
    "title_canon_sha256": "032d9d01a815da6e9f78a3e10eee32882c81e27900146a05d524f60efde6fba6"
  },
  "schema_version": "1.0",
  "source": {
    "id": "2605.06322",
    "kind": "arxiv",
    "version": 2
  }
}