REVIEW 4 major objections 6 minor 39 references
Investigating Language Model Capabilities to Represent and Process Formal Knowledge: A Preliminary Study to Assist Ontology Engineering
T0 review · 4 major / 6 minor · reviewed 2026-08-15 · deepseek-v4-flash
Pith's one-line read This paper claims that small language models can be fed compact formal logic grammars instead of natural language and still reason nearly as well, with CLIF matching NL on Flan-T5-small and falling only slightly behind on Flan-T5-large.
desk verdict Useful new grammar comparison on FOLIO, but the CLIF-vs-NL claim is unproven because the CLGC pipeline is not meaning-preserving and demonstrably corrupts at least one target grammar. 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 machinery is a pipeline that converts first-order logic formulas between grammars: it parses FOL with a BNF grammar, builds a parse tree, maps the tree to a target grammar (CLIF, CGIF, TFL, TFL+, MINIFOL), and regenerates the text. This pipeline plus the Syllogistic Evaluation Framework (SEF), which classifies each FOLIO problem as Disjunctive, Hypothetical, Categorical, or Complex, defines the experimental comparison. The conversion step is load-bearing because all accuracy differences across grammars are attributed to the language itself; if the conversions change logical meaning, the comparison collapses.
What would settle it
Count, over the whole FOLIO test and validation sets, how many transformed formulas differ in satisfiability or truth value from their FOL originals (e.g., the shown MINIFOL output for ¬(Manager(james) ⊕ AppearIn(james, company)) is (manager(james) ∧ appearin(james, company)), which is satisfiable when the original is false). If even a small percentage of inputs are corrupted, the accuracy comparisons across grammars no longer compare the same reasoning problems.
Extended reading notes
Core claim
The central claim is that the choice of the formal representation matters less than the literature assumes: a compact logical grammar, CLIF, can carry first-order reasoning tokens nearly as well as natural language in small models. The evidence comes from a controlled comparison across six models, seven input languages, and three learning settings, with FOLIO as the fixed reasoning benchmark. In the strongest setting, supervised fine-tuning on an A100 GPU, Flan-T5-large reaches 0.6157 accuracy with CLIF against 0.6600 with natural language, and Flan-T5-small ties natural language exactly at 0.4384. The authors conclude that no single grammar outperforms natural language, but compact formalisms come close enough to be viable substitutes, especially for models under three billion parameters.
Load-bearing premise
The conversion from first-order logic to each alternative grammar must preserve the meaning of every formula, but no equivalence proof or automated verification is supplied, and Table 3 shows a MINIFOL output that is not equivalent to its FOL input.
Editorial extensions
If this is right
- Compact formal grammars like CLIF can be used to shorten LM inputs without giving away much reasoning accuracy, so they may be practical for low-resource settings.
- The conclusion is not that NL is best, but that a compact grammar is competitive; thus grammar choice should be measured alongside model size and training method.
- Grammar prompting helps in zero-shot but not few-shot or fine-tuning, so its benefit is setting-dependent.
- Tokenizer re-training on a compact grammar can boost small models (e.g., Flan-T5-small on TFL+) but does not scale to larger models.
- SEF-based breakdown shows performance is concentrated in Disjunctive and Hypothetical syllogisms, with Categorical too sparse to evaluate.
Reading between the lines
- If the CLGC conversions were verified to preserve first-order meaning, the accuracy gap between CLIF and NL would measure representation cost directly; one testable extension is to run the same comparison on datasets like ProofWriter or RuleTaker, where formulas are synthetic and can be checked for equivalence exactly.
- The observed CLIF-vs-NL closeness suggests an input-compression effect: the model may be using the same latent reasoning machinery while struggling less with surface forms; this could be tested by measuring accuracy versus the amount of fine-tuning data for CLIF and NL.
- For ontology engineering, the practical implication is that SLMs could consume ontology axioms in CLIF directly, shrinking prompts and avoiding paraphrase ambiguity; this is an extension beyond the paper's experiments, which stop at FOLIO-style reasoning.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript investigates whether small language models (SLMs) can reason over first-order logic problems when the input is expressed in formal grammars rather than natural language. The authors introduce the Syllogistic Evaluation Framework (SEF) for classifying FOLIO reasoning pairs and the Common Logic Grammar Construction (CLGC) pipeline that translates the FOLIO FOL annotations into CLIF, CGIF, TFL, TFL+, and a custom MINIFOL. They then evaluate Flan-T5-small/base/large, GPT-2, Phi-3.5-mini-instruct, and Gemma-2-2b-it under supervised fine-tuning (with and without LoRA), zero-shot prompting, and 8-shot prompting, with additional variations including grammar-context passing and tokenizer re-training. The main claim is that CLIF, a compact formal language, can largely substitute for natural language while preserving SLM reasoning performance, based on CLIF matching or closely trailing NL in Tables 5 and 6. The paper concludes that compact formal representations are viable for bootstrapping ontology engineering with SLMs, though it positions the work as preliminary.
Significance. The paper addresses a timely and practical question—whether the input representation of logical problems can be made more compact without hurting SLM performance—with a broad configuration matrix spanning multiple models, grammars, and training regimes on the public FOLIO benchmark. The SEF syllogism-type breakdown in Table 13 is a useful descriptive lens, and the tokenizer re-training comparison in Table 12 is an interesting exploratory direction. The central claim is falsifiable and, if substantiated, would be practically relevant for ontology engineering because it would permit more efficient encoding of logical knowledge for SLMs. However, the empirical evidence as presented does not yet establish the claim: the transformation pipeline that generates the formal-language datasets is not shown to be meaning-preserving, and the headline comparisons lack statistical support. The paper's strengths are its scope and the specificity of the research questions; those strengths would be better leveraged by pairing the wide comparison with a smaller set of rigorously verified and repeated experiments.
major comments (4)
- [Section 3.2.3 and Table 3] The CLGC pipeline is not demonstrated to preserve the truth conditions of the FOL formulas it translates. For instance, the formula ¬(Manager(james) ⊕ AppearIn(james, company)) is rendered in MINIFOL as (manager(james) ∧ appearin(james, company)), which is not logically equivalent; the rows for ∀x ((Employee(x)∧(¬In(x, homecountry)))→Work(x, home)) and ∀x (Manager(x) → ¬Work(x, home)) drop the negations on ¬In and ¬Work in both MINIFOL and CGIF. Since all formal-language datasets used in the Section 4 experiments are produced by this pipeline, the accuracy comparisons for CLIF, CGIF, TFL, TFL+, and MINIFOL are only interpretable if every generated formula is verified to be logically equivalent to its FOL source. At minimum, the authors need to provide an automated equivalence check (or a released dataset with per-formula verification) and to rerun or clearly qualify the affected results.
- [Sections 4.1-4.2, Tables 5-6] All reported metrics are from single runs with no error bars, confidence intervals, or significance tests. The headline CLIF-vs-NL difference for Flan-T5-large in Table 6 is 0.6600 vs 0.6157 in accuracy; without repeated seeds or a significance test, this gap is within plausible random variation and cannot support the claim that CLIF ties or ranks second-best to NL. The same issue affects the grammar-prompting comparison in Table 8, where only one model is used and metric changes are inconsistent (e.g., CLIF F1 improves while precision drops; TFL+ precision drops from 0.5634 to 0.3618).
- [Section 4.2, Table 5] The comparison between Flan-T5-small and the larger models is confounded by the fine-tuning setup. Flan-T5-small rows are fully fine-tuned without LoRA, whereas the Flan-T5-large rows are marked with an asterisk and use PEFT-LoRA. Consequently, the text's claim that the smallest model outperforms larger, fine-tuned models is not supported by the table: Flan-T5-large* achieves a higher accuracy than Flan-T5-small on NL (0.4729 vs 0.4384). Any conclusion about model-size effects must compare models trained with the same fine-tuning procedure.
- [Section 4.2, Tables 9-10] Several rows across different models and grammars report exactly identical metrics (e.g., accuracy 0.3546, precision 0.1182, recall 0.3333, F1 0.1745 for many entries in Table 9, and for all entries in Table 10). This strongly suggests that these configurations collapse to a constant prediction, such as always predicting the majority class, and therefore those rows carry no information about the language being tested. The paper should report per-configuration prediction distributions and should not use such rows to draw conclusions about grammar performance, for example the statement in Section 4.2 that CLIF is a more compact contender in the 8-shot setting.
minor comments (6)
- [Abstract] The sentence 'Our findings show that it is possible to substitute Natural Language (NL) with a more compact logical language while maintaining a strong performance on reasoning tasks and hope to use these results...' is a fragment; the subject of 'hope' is unclear and the sentence should be rewritten.
- [Algorithm 1] Algorithm 1 uses the variable D in the loop over statements without defining it in the Require or Ensure block; please clarify the notation so the loop is unambiguous.
- [Section 2.1, reference [29]] Reference [29] (a paper on jailbreaking via language games) does not appear to support the claim that the language in which a model receives a problem affects its success rate; a more directly relevant citation on input representation or prompt language effects would be appropriate.
- [Section 4.2, Table 8] The text says that Table 8 shows CLIF outperforming all other languages in the zero-shot setting, but the table only reports Gemma-2-2b-it on CLIF, FOL, TFL+, and TFL; it does not include NL, CGIF, MINIFOL, or the other models, so the statement is stronger than the evidence.
- [Table 12] The Tokenizer Re-Train column lists the CLIF condition with vocabulary size 32128 for both 'Yes' and 'No', which is confusing because re-training without resizing should preserve the size; clarify whether the re-trained CLIF tokenizer was resized and unify the notation.
- [Section 4.2, Table 14] The prose describing Table 14 says the model reasons 'False' as opposed to 'Uncertain' on a single occasion, but the table shows several label differences across NL, CLIF, and TFL+; describe the error pattern more precisely so the reader can map the text to the table.
Circularity Check
No circularity: the paper is an empirical benchmark whose central claim rests on held-out model evaluations, not on a self-citing derivation or a fitted parameter.
full rationale
The paper's central claim—that compact logical languages such as CLIF can substitute for natural language while maintaining strong reasoning performance—is an empirical finding supported by supervised fine-tuning and prompting experiments on held-out splits of FOLIO. The CLGC pipeline transforms existing FOL annotations into alternative grammars; this is data preprocessing, not a derivation that presupposes the conclusion. The grammars come from external standards or literature (CLIF, CGIF, TFL) or are introduced as experimental formats (MINIFOL, TFL+), and no fitted parameter is used to construct the reported accuracy differences. The paper contains no load-bearing self-citation: the cited prior work provides datasets, baselines, and related techniques, but the headline comparison is generated by the paper's own runs. The Table 3 transformation discrepancies (e.g., the MINIFOL rendering of a negated XOR as a conjunction) are a legitimate correctness and validity concern for the preprocessing pipeline, but they are not a circularity: even if the transformations are lossy, the model accuracies are measured on independently held-out examples rather than being forced by the transformation definitions. The reported CLIF-vs-NL gaps therefore are empirical findings that could be wrong or unverified, but they are not circular in structure. The paper is self-contained as an experimental study, so the appropriate circularity score is 0.
Assumptions & free parameters
free parameters (4)
- LoRA configuration for PEFT fine-tuning =
r=16, lora_alpha=32, target q,v, dropout 0.05
- SFT training epochs =
5 without LoRA, 10 with LoRA
- Re-trained tokenizer vocabulary size =
191 for TFL, 180 for TFL+
- Number of few-shot examples =
8
assumptions (3)
- domain assumption The FOLIO dataset ground truth labels are correct.
- domain assumption The CLIF, CGIF, and TFL grammar implementations in the CLGC pipeline faithfully follow their published definitions.
- ad hoc to paper Parse-tree transformation between grammars preserves the truth conditions of each formula.
invented entities (2)
-
MINIFOL
-
TFL+
Cite this review
Pith. "Pith review of Investigating Language Model Capabilities to Represent and Process Formal Knowledge: A Preliminary Study to Assist Ontology Engineering." pith.science (2026). https://pith.science/paper/LULR7HGA
@misc{pith2026250910249,
author = {Pith},
title = {Pith review of: Investigating Language Model Capabilities to Represent and Process Formal Knowledge: A Preliminary Study to Assist Ontology Engineering},
year = {2026},
howpublished = {\url{https://pith.science/paper/LULR7HGA}},
note = {Machine review of arXiv:2509.10249}
}
read the original abstract
Recent advances in Language Models (LMs) have failed to mask their shortcomings particularly in the domain of reasoning. This limitation impacts several tasks, most notably those involving ontology engineering. As part of a PhD research, we investigate the consequences of incorporating formal methods on the performance of Small Language Models (SLMs) on reasoning tasks. Specifically, we aim to orient our work toward using SLMs to bootstrap ontology construction and set up a series of preliminary experiments to determine the impact of expressing logical problems with different grammars on the performance of SLMs on a predefined reasoning task. Our findings show that it is possible to substitute Natural Language (NL) with a more compact logical language while maintaining a strong performance on reasoning tasks and hope to use these results to further refine the role of SLMs in ontology engineering.
Figures
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Reviewed August 15, 2026 · model on record in the stance chip above.
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