arXiv AI

Order-Invariant Answers, Order-Sensitive Representations in Mathematical Reasoning

The study examines whether language models maintain invariant internal representations when the order of mathematical rules is permuted, even though the correct answer remains unchanged. Using synthetic multi-step function‑composition tasks, the authors measure accuracy and a permutation signal‑to‑noise ratio (SNR) across 16 models (1B–8B parameters). They find a strong positive correlation (up to 0.86 Spearman) between higher accuracy on reordered problems and more distinct internal representations of rule orderings, indicating that successful reasoning can coexist with representation sensitivity.

arXiv AI
Jul 24

Representation Robustness Under Executable Reasoning Constraints in Large Language Models for Mathematical Problem Solving

arXiv:2607. 20520v1 Announce Type: new Abstract: Large language models (LLMs) are increasingly evaluated on mathematical problem solving, yet prior work often treats representationally equivalent formulations as interchangeable and conflates reasoning errors with interface failures.

By Sagnik Nath, Edith Aurora Graf, Liang Zhang, Diego Zapata-Rivera
arXiv Computation and Language
Sep 7

Beneath the Surface of Chains-of-Thought: A Mechanistic Interpretation of Reasoning Operations in LLMs

The paper investigates how large language models (LLMs) organize reasoning operations—such as problem formulation, goal decomposition, and deduction—within their hidden representation spaces. It shows that these operations are separable in held‑out representations, with peak separability in middle layers, and that token‑wise alignment of operations becomes more distributed across spans as layers deepen. Attention‑masking experiments reveal that representations aligned to operations at chunk onsets depend on prior reasoning context, indicating a geometric correspondence between linguistic reasoning expressions and internal model structure.

By Seogyeong Jeong, Jaehui Hwang, Dongyoon Han, Geonmo Gu, Alice Oh, Taekyung Kim
arXiv Machine Learning
Sep 23

Same Quantity, Different Answer: Numerical Representation Invariance in Language Models

The paper introduces a benchmark of 3,600 exact‑rational word problems and 8,600 prompts that test whether language models give the same canonical answer when the same quantity is expressed in different numeric forms (decimal, fraction, percentage, number word, scientific notation, or unit‑converted). After normalizing answer syntax, canonical accuracy is high (0.969–0.996), but correctness across equivalent representations drops to 0.848–0.981, revealing that many errors stem from the evaluator’s number grammar rather than the models’ reasoning. The study also finds that representation consensus does not outperform paraphrase consensus on low‑error subsets and that certain models (e.g., Mistral Small 4) exhibit systematic unit‑conversion errors.

By Ephraim Atta-Duncan
arXiv AI
Sep 7

Shared circuits predict whether LLMs generalize across formats in arithmetic reasoning

The study investigates whether large language models (LLMs) can generalize arithmetic reasoning across different input formats, such as numeric and verbal expressions in English, Spanish, and Italian. By using attribution patching, the researchers identified the specific internal circuits each model employs for numeric versus verbal arithmetic tasks. They found that the degree of overlap between a model’s numeric circuit and its verbal circuit predicts how well the model generalizes to verbal formats, explaining variations in performance across languages and formats without requiring labeled data.

By Andrea Gregor de Varda, Sana Pandey, Pengrui Han, Jacob Andreas, Evelina Fedorenko
arXiv AI
Oct 9

Structure Tax: How Structured Output affects LLMs Performance

The paper investigates the so‑called ‘structure tax’ that is often attributed to constraining large language model outputs to structured formats like JSON or XML. By evaluating various models, datasets, and schema designs, the authors find that the accuracy loss depends more on how the schema is organized than on the presence of structure itself. Specifically, reasoning‑first field ordering can match or surpass free‑form accuracy, whereas answer‑first ordering leads to significant drops, especially in smaller models. The study also shows that well‑designed schemas improve confidence calibration and the separability of correct versus incorrect representations in transformer layers.

By Vineet Kumar, Kanishka, Bhuvanesh Mandora
arXiv Machine Learning
Sep 10

Do Reasoning Representations Help Humans Evaluate LLM Outputs?

The paper investigates whether reasoning representations—explanations for large language model outputs—aid humans in evaluating those outputs. A controlled human study tested six reasoning formats across tasks of varying complexity, measuring structural understanding, error detection, and trust calibration. Results revealed a mismatch: participants favored planning- and decomposition-based representations, yet simpler chain-of-thought traces better supported verification, trust, and interpretability, while preferred formats increased calibration risks.

By Jaewoo Lim, Sungbok Shin, Sanghyun Hong
arXiv Computation and Language
Sep 4

Lost in Reordering: Structural Sensitivity of Multilingual LLMs under Semantics-Preserving Perturbations

The paper introduces IndicReStruct, a benchmark dataset comprising two variants—GSM8K-Reordered and GSM8K-Voice—derived from GSM8K to test multilingual LLMs on Hindi and Malayalam. It evaluates six state‑of‑the‑art LLMs under constrained constituent reordering and active‑passive voice transformation, finding consistent and significant drops in mathematical reasoning performance. Qualitative error analysis and residual‑stream activation patching reveal that failures often stem from disrupted entity‑quantity alignment, with intermediate transformer layers playing a key role in restoring reasoning.

By Karthika Nhayakkat, Rajat Verma, Maharaj Brahma, Vetcha Gnana Mahesh, Maunendra Sankar Desarkar, Ganesh Ramakrishnan, Rohit Saluja