REVIEW 3 major objections 6 minor 33 references
Can LLMs Help Create Grammar?: Automating Grammar Creation for Endangered Languages with In-Context Learning
T0 review · 3 major / 6 minor · reviewed 2026-08-11 · deepseek-v4-flash
Pith's one-line read An LLM with in-context learning can generate coherent grammar for endangered Moklen from just a dictionary and parallel sentences, with 86 of 100 lexical entries judged accurate.
desk verdict A genuinely new task with a clean pipeline, but the evaluation never checks whether the generated grammar actually parses, so the central claim is not yet supported. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The mechanism is an in-context learning pipeline with five stages: a dictionary-based tokeniser using longest-match segmentation; sense mapping that attaches English glosses to each Moklen token; concatenation of word-by-word glosses into a string that mirrors Moklen word order; prompting the LLM with these materials plus XLE documentation and optional self-explanation; and finally using the generated grammar rules to prompt lexical entries for unseen dictionary words. The load-bearing formal object is the XLE grammar, a computational implementation of Lexical-Functional Grammar whose rules and lexical entries pair constituent structure with functional structure. The pipeline's effect is to give the LLM enough aligned local evidence to infer word order, parts of speech, and lexical schemata by analogy with English, without any Moklen text in pretraining.
What would settle it
Have a second linguist with no access to Spencer (2022) independently write a reference grammar of Moklen from primary fieldwork, then compare it rule-by-rule with the gold standard and with the generated XLE grammar; if the independent grammar disagrees on core word order, parts of speech, or lexical senses, the evaluation baseline is unreliable. A more computational check is to feed the generated grammar to the XLE parser on the 40 held-out sentences and require a successful parse and f-structure for sentences the gold grammar parses.
Extended reading notes
Core claim
The central discovery is that GPT-4o-mini, a small API-based LLM, can induce a coherent XLE grammar and useful lexical entries for a language it has not been trained on, provided its prompt contains a bilingual dictionary, tokenised and sense-mapped parallel sentences, and XLE documentation. The authors find that the most effective context for translation is tokenised dictionary senses plus concatenated word-by-word meanings plus self-explanation (TD+C+S), and that adding grammar to the prompt improves translation scores across most settings. In direct evaluation, 86 out of 100 lexical entries generated for Moklen words absent from the bitext were judged accurate and coherent, while the main observed error type was missing secondary senses of polysemous words and an over-application of English parts of speech such as determiners. This is framed as evidence that LLMs can assist language documentation, not replace it.
Load-bearing premise
The accuracy judgements presuppose that the unpublished reference grammar of Moklen used as the gold standard is correct and complete, and that the dictionary covers every word appearing in the bitext; if either premise fails, the reported accuracy numbers stop supporting the conclusions.
Editorial extensions
If this is right
- If correct, grammar construction for endangered languages could begin from a bilingual wordlist and a few dozen recorded sentences, greatly lowering the cost of formal grammar writing.
- Generated lexical entries can extend a dictionary to words not present in any sentence corpus, since 86 of 100 entries in the study were judged accurate.
- Adding the generated grammar to the prompt improves translation quality, suggesting grammar rules and lexical resources can feed back into machine translation.
- The same prompting strategy may transfer to other formal grammar frameworks beyond XLE, such as dependency grammars or HPSG, as the paper suggests.
Reading between the lines
- A testable extension is to run the identical pipeline on a morphologically rich endangered language; the paper's limitation note suggests the isolating typology of Moklen may be doing much of the work, so success on agreement-heavy languages would be a stronger test.
- The BERTScore gain after adding grammar could partly reflect the evaluator's sensitivity to content-word overlap rather than true syntactic understanding, so a parse-based evaluation of the generated XLE grammar against independently collected sentences would separate the two.
- Hallucinated categories that the model inserted into Moklen grammar, such as determiners, might function as hypotheses for field linguists to check, turning model errors into a discovery aid.
- Dictionary completeness is the quiet precondition: the tokeniser fails if the bitext contains words absent from the dictionary, so field applications would need a morphological guesser or a mechanism to flag out-of-vocabulary items.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes using GPT-4o-mini with in-context learning to generate formal XLE (LFG) grammar rules and lexical entries for Moklen, an endangered Austronesian language, using only a bilingual dictionary and a small parallel bitext. The method consists of dictionary-based tokenisation, sense mapping, concatenation of per-word translations, and a prompt that varies several context types (bitext, tokenisation, dictionary, concatenated sentence, XLE example, self-explanation). Translation BERTScore is used to select among 48 context combinations; grammar rules are evaluated qualitatively against a gold standard constructed from Spencer (2022); lexical entries for 100 words not in the bitext are manually assessed against dictionary definitions. The paper reports that the TD+C+S context combination achieves BERTScore F1 of 0.7110 for Moklen-to-English translation when an XLE gold-standard grammar is added to the prompt, and that 86 of 100 generated lexical entries are accurate.
Significance. If properly validated, the approach would be a valuable contribution to language documentation, where manual grammar engineering is a major bottleneck. The paper deserves credit for working with a real endangered language, deliberately using a small model, and for stating that data, code, and model generations are in the supplementary material. However, the current evidence does not establish the central claim that the model generates a coherent XLE grammar: no parser is run on the generated grammar, the grammar gold standard is an unpublished manuscript by the first author, and the headline translation number appears to be selected on the test set. These are not merely presentation issues; they affect the validity of the main results. The idea is promising, but the paper needs substantially stronger validation before publication.
major comments (3)
- [Section 6.1] The reported peak BERTScore F1 of 0.7110 for TD+C+S is obtained after exploring 48 context combinations, and the evaluation appears to use the same 40-sentence parallel set described in Section 5.2 as the basis for selecting the best context. If so, the headline number is an in-sample selection optimum, and the comparison among contexts does not support the claim that TD+C+S is the best setting. Please clarify the exact split between the ablation set and the evaluation set, and ideally re-run context selection on a development set with a held-out test set.
- [Sections 5.2 and 6.2] The grammar-rule evaluation relies on a gold standard that the authors 'attempt to create one based on Spencer (2022)', an unpublished manuscript by the first author. That source is neither available to readers nor independently verified, so the accuracy judgements for grammar rules are non-reproducible and potentially circular. More importantly, the paper never runs the XLE parser on the generated grammar and lexical entries, even though 'coherent XLE grammar' is the central claim. The translation improvements in Section 6.1 are obtained by adding the 'XLE gold standard grammar' to the prompt, not the grammar produced by the model, so those results do not validate the generated grammar. Section 6.2 also reports no quantitative accuracy or coverage score for the grammar rules.
- [Section 6.3] The 86/100 lexical-entry accuracy is assessed by comparing generated entries to dictionary definitions that were also provided as context in the prompt (Sections 4.3 and 5.2). This makes the evaluation partly circular: high agreement with the input dictionary does not demonstrate that the model has learned Moklen grammar or generalised beyond the provided lexicon. In addition, the manual assessment is reported without a blind protocol or inter-annotator agreement, so the 86% figure is difficult to interpret.
minor comments (6)
- [Abstract] The abstract contains typographical and grammatical errors, including 'Yes!' at the start and 'We takes Moklen as a case study'; please copyedit the entire manuscript.
- [Sections 5.1 and 6.1] There are unresolved cross-references 'See ?? for full details' in Sections 5.1 and 6.1, and several figure captions are malformed or incomplete (for example, Figure 3 lacks a clear legend and readable axis labels).
- [Section 5.2] The paper lists BLEU, ROUGE, METEOR, chrF, and BERTScore as evaluation metrics, but Section 6.1 reports only BERTScore; please report the other metrics or explicitly justify their omission.
- [Section 4.1] The tokeniser depends on the assumption that every word in the Moklen bitext appears in the dictionary; please verify this against the actual data and report the number of out-of-dictionary tokens, if any.
- [Section 6.2] The section title is 'Grammar Rules: Accuracy and Completeness', but no accuracy numbers are given; either add a quantitative evaluation or rename the section to reflect the qualitative discussion.
- [Limitation] The limitation section addresses typological generality, but it does not mention the lack of parser validation or the reliance on an unpublished gold standard; both should be acknowledged.
Circularity Check
Lexical-entry accuracy is assessed against the dictionary definitions already given in the prompt, and grammar-rule accuracy is graded against a gold standard built from the first author's unpublished manuscript; the central XLE-parsing claim is unevaluated but the derivation is not fully circular.
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fitted input called prediction
[Section 5.2 (Lexical Entry and Schemata Accuracy) and Section 6.3 (Lexical Entries: Accuracy and Coherence)]
"The model will generate lexical entries for 100 words from the Moklen dictionary that do not appear in the bitext, primarily based on the grammar rules produced by the model and the information provided in the dictionary. ... We generated lexical entries for 100 Moklen words not present in the bitext and assessed their accuracy by comparing them to existing dictionary definitions. Out of these, 86 entries were deemed accurate and coherent."
The dictionary definitions are the input used to generate the lexical entries, and the same dictionary definitions are the reference against which accuracy is measured. The 86/100 accuracy therefore largely measures whether the model reformatted information that was already in the prompt; it is not an independent prediction of new lexical knowledge. The score is partly forced by construction rather than by the generated grammar's quality.
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self citation load bearing
[Section 5.2 (Grammar Rule Accuracy)]
"Never before had Moklen been developed its grammar using XLE. Hence, there is no XLE grammar for Moklen; we attempt to create one based on Spencer (2022) and served as a gold standard."
The gold standard used to judge whether the LLM's grammar rules are 'coherent' is an unpublished manuscript by the paper's first author. The evaluation of the central grammar-generation claim therefore rests on a self-authored, unverified standard: the judgment reduces to whether the LLM's output matches the authors' prior analysis, with no independent parser check or externally validated grammar to break the loop. This is not a formal tautology because the LLM never sees Spencer (2022), but the load-bearing evidence for the central claim is a self-citation.
full rationale
The paper's central claim is that gpt-4o-mini produces coherent XLE grammar and lexical entries for Moklen. The derivation chain is not fully circular: the generation step does use only the dictionary, parallel sentences, and XLE documentation, and the translation experiments are an independent (though weak) signal. However, the two direct evaluations of the generated outputs are both anchored to inputs or to the authors' own prior analysis. Lexical-entry accuracy compares the outputs to the dictionary definitions that were fed into the prompt, making the 86/100 figure a self-consistency check rather than an independent validation. Grammar-rule accuracy uses a gold standard 'attempt[ed]' from Spencer (2022), an unpublished manuscript by the first author, so the coherence verdict is not independently established. The headline BERTScore result (0.7110) is also reported for a condition that incorporates the XLE gold standard grammar rather than the generated grammar, so it does not directly verify the generated grammar. No experiment feeds the generated grammar into the XLE parser; that is a correctness and completeness risk, not itself circularity. Weighing these, the central ability claim has some independent content (translation improvements, manual coherence observations), but the most precise accuracy numbers reduce to matching prompt inputs or to a self-authored gold standard. Score 4 reflects partial circularity in the evaluation of the key outputs rather than a fully forced derivation.
Assumptions & free parameters
assumptions (5)
- domain assumption Moklen is an isolating language with no inflectional morphology, so words can be segmented purely with a dictionary and longest-match tokenisation.
- domain assumption Every word in the bitext appears in the Moklen-English dictionary, so the tokeniser can segment all sentences.
- domain assumption The gold standard XLE grammar for Moklen, based on Spencer (2022), is a correct reference for evaluating generated grammar.
- domain assumption BERTScore is a meaningful measure of translation quality for Moklen, and score differences reflect grammar quality.
- domain assumption GPT-4o-mini has effectively zero prior knowledge of Moklen, so any correct output must come from in-context learning.
Cite this review
Pith. "Pith review of Can LLMs Help Create Grammar?: Automating Grammar Creation for Endangered Languages with In-Context Learning." pith.science (2026). https://pith.science/paper/V37T566Q
@misc{pith2026241210960,
author = {Pith},
title = {Pith review of: Can LLMs Help Create Grammar?: Automating Grammar Creation for Endangered Languages with In-Context Learning},
year = {2026},
howpublished = {\url{https://pith.science/paper/V37T566Q}},
note = {Machine review of arXiv:2412.10960}
}
read the original abstract
Yes! In the present-day documenting and preserving endangered languages, the application of Large Language Models (LLMs) presents a promising approach. This paper explores how LLMs, particularly through in-context learning, can assist in generating grammatical information for low-resource languages with limited amount of data. We takes Moklen as a case study to evaluate the efficacy of LLMs in producing coherent grammatical rules and lexical entries using only bilingual dictionaries and parallel sentences of the unknown language without building the model from scratch. Our methodology involves organising the existing linguistic data and prompting to efficiently enable to generate formal XLE grammar. Our results demonstrate that LLMs can successfully capture key grammatical structures and lexical information, although challenges such as the potential for English grammatical biases remain. This study highlights the potential of LLMs to enhance language documentation efforts, providing a cost-effective solution for generating linguistic data and contributing to the preservation of endangered languages.
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Reviewed August 11, 2026 · model on record in the stance chip above.
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