Computation and Language · Cross-listed from cs.LG
AutoRAGTuner: A Declarative Framework for Automatic Optimization of RAG Pipelines
Xintan Zeng, Yongchao Liu, Yice Luo et al. (+1 more)
Retrieval-Augmented Generation (RAG) enhances LLMs, but performance is highly sensitive to complex architecture designs and hyper-parameter configurations, which currently rely on inefficient manual tuning. We present AutoRAGTuner, a declarative, configuration-driven framework that automates the RAG life cycle: construction, execution,evaluation, and optimization. AutoRAGTuner employs a modular architecture to decouple pipeline stages through a component registration mechanism. To unify heterogeneous data, we introduce the Domain-Element Model (DEM), representing objects as atomic elements with bidirectional pointers to support nodes, edges, and hyperedges. Furthermore, AutoRAGTuner integrates an adaptive
Bayesian optimization engine for end-to-end hyper-parameter tuning. Experimental results demonstrate AutoRAGTuner's architectural generality: across diverse RAG pipelines, ranging from vanilla to graph-based, the framework consistently outperforms default baselines. Notably, AutoRAGTuner significantly mitigates engineering overhead, where its declarative configuration
language enables a up to 95% reduction in code churn for architectural adjustments. Overall, AutoRAGTuner provides a systematically optimizable foundation for building evolvable and reusable RAG systems.
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All authors Xintan Zeng, Yongchao Liu, Yice Luo, Jiajun Zhen
Computation and Language
EditPropBench: Measuring Factual Edit Propagation in Scientific Manuscripts
Garvin Kruthof
Local factual edits in scientific manuscripts often create non-local revision obligations. If a
dataset changes from 215 to 80 documents, claims such as 'medium-scale' or 'a few hundred items' may also become stale, even though they do not repeat the edited number. In an audit of recent arXiv cs.CL
benchmark and
dataset papers, we find fact-dependent qualitative claims in 37.2% of papers, suggesting that this dependency pattern is common in the target genre. We introduce EditPropBench, a
benchmark for measuring whether LLM editors propagate factual edits through dependent manuscript claims. Each item contains an ML/NLP-style synthetic manuscript, a targeted edit, and a controlled fact graph with sentence-level labels for direct targets, required downstream updates, and unrelated text that should remain unchanged. We summarize cascade success with Edit-Ripple Adherence (ERA), the fraction of required downstream updates correctly revised, and validate the metric with
adversarial probes and stress-test variants. On the hardest cases, where dependent claims use implicit or free-form wording rather than repeating the edited value, five LLM editing systems span ERA 0.148-0.705. Even the strongest misses roughly 30% of required cascade updates. This advantage persists in a mixed evaluation that includes easy cases solvable by deterministic substitution. EditPropBench shows that current LLM editors can repair many implicit consequences of factual edits, but reliable scientific revision still requires cascade-aware checking.
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Computation and Language
Enhanced LLM Reasoning by Optimizing Reward Functions with Search-Driven Reinforcement Learning
Arash Ahmadi, Sarah Sharif and Yaser Banad
Mathematical
reasoning is a key
benchmark for large
language models. Reinforcement learning is a standard post-training mechanism for improving the
reasoning capabilities of large
language models, yet performance remains sensitive to the design of the reward function that drives policy optimization. This paper introduces a search-driven framework that treats the reward specification itself as an object of optimization. The setting of interest is one in which the base model is held fixed and the reward specification is the primary remaining design lever. Candidate reward functions are generated by a frontier
language model, validated automatically, screened through 500-step Group Relative Policy Optimization (GRPO) training runs on a Llama-3.2-3B-Instruct base model with Low-Rank Adaptation (LoRA), and ranked by F1 on the GSM8K test set. Ranked summaries from prior rounds are then fed back into the next round of generation. Over five rounds, the search produces 50 candidate rewards. The mean F1 rises from 0.596 in Round 1 to 0.632 in Round 5, and the top individual reward reaches F1 = 0.787. Seven ensemble configurations of top-ranked rewards are evaluated. The best ensemble achieves F1 = 0.795 (95% bootstrap CI [0.756, 0.832]) and accuracy 0.660 [0.635, 0.686], a 0.19 absolute F1 gain over a base-rewards-only GRPO baseline (F1 = 0.609). Pairwise McNemar tests with Bonferroni correction show all five-or-more-reward configurations are statistically indistinguishable at {\alpha} = 0.05/21. A three-seed re-training of the best ensemble yields F1 of 0.785. A randomly drawn 5-reward control collapses to F1 = 0.047, which shows that the ranked-feedback loop, not the additive signal of having more rewards, drives the gain.
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Computation and Language
Pair2Score: Pairwise-to-Absolute Transfer for LLM-Based Essay Scoring
İbrahim R{\i}za Hallaç and Hasan Oğul
Many scoring applications require absolute predictions, while pairwise comparisons can provide a simpler learning objective. We present Pair2Score, a two-stage learning framework that transfers pairwise comparisons into absolute scoring with parameter-efficient LLaMA adaptation. Stage 1 trains a directional Siamese ranker on pairwise comparisons derived from absolute trait labels; Stage 2 trains an absolute predictor using configurable transfer strategies (warm-start and
embedding-fusion variants). We evaluate on rubric-aligned Automated Essay Scoring (AES) traits (grammar, vocabulary, syntax) under a five-fold protocol that co-rotates held-out fold and random seed. At the trait level, the best-performing transfer variant improves quadratic weighted kappa (QWK) over an absolute-only baseline for all three traits. However, not all transfer configurations help: a one-epoch pairwise stage transfers more reliably than extended pairwise training, and transfer configuration – not just the inclusion of a pairwise stage – determines whether downstream scoring benefits.
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Computation and Language
Methods, Data, and Conceptual Change: Reflections from Two Quantitative Diachronic Case Studies
Catherine Wong, Bach Phan-Tat and Susan Fitzmaurice
This discussion paper reflects on how quantitative approaches to historical linguistics interact with
dataset properties. Drawing on two worked examples, we examine English data using quad-based concept modelling of Early Modern English discourse in EEBO-TCP (c. 1470s-1690s; 765M words) alongside SynFlow analysis of scientific writing in Royal Society Corpus 6.0.4 (1750-1799; drawn from a 78.6M-
token open corpus). Through parallel comparison, the paper explores how each approach operationalises concepts, the data assumptions they entail, and the diachronic interpretations they support. We argue that comparative methodological reflection clarifies the limits of purely lexical, frequency-based approaches and highlights how
dataset structure shapes the kinds of semantic change that quantitative methods can reliably detect.
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Computation and Language
What Single-Prompt Accuracy Misses: A Multi-Variant Reliability Audit of Language Models
Ranit Karmakar and Jayita Chatterjee
Single-
prompt accuracy is the dominant way to
benchmark language models, but it can miss reliability failures that matter. We evaluate a 15-model open-weight corpus, with the main reliability analyses focused on 10 instruct models across five classification and
reasoning benchmarks under five
prompt variants each, measuring accuracy,
token-probability calibration, verbal-confidence calibration, verbal parse rate, and
prompt-perturbation spread for every (model x
dataset x variant)
cell. We find three broad results. First, evaluation design can materially change the conclusion. Switching Expected Calibration Error (ECE)
token from a raw to a label-set-normalised definition changes per-
cell calibration by a mean absolute 0.149. More strikingly, pairing a chain-of-thought
prompt with a first-character evaluator on ARC-Challenge reduces apparent accuracy by 72-88% across all five primary models; two independent repair procedures recover 93.8% and 102.7% of the lost performance, indicating an evaluator-side rather than model-side failure. Second, confidence signals are fragile. On MMLU-Pro, every primary model verbally reports confidence substantially above both its accuracy and its
token-probability confidence on the same rows, and verbal parse rate can collapse for a single model on a single
prompt variant. Third,
prompt robustness does not track parameter count reliably. Across 10 instruct models, the correlation between model size and
prompt-perturbation spread ranges from -0.244 to 0.474 across
benchmarks. Taken together, these results show that reliability conclusions for small
language models depend not only on the model being evaluated, but also on the evaluation pipeline used to measure it. We argue that calibration definitions, evaluator logic, verbal parseability, and
prompt robustness should be reported explicitly when making reliability claims.
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Computation and Language
VIDA: A Dataset for Visually Dependent Ambiguity in Multimodal Machine Translation
Jingheng Pan, Xintong Wang, Longyue Wang et al. (+3 more)
Ambiguity resolution is a key challenge in
multimodal machine translation (MMT), where models must genuinely leverage visual input to map an ambiguous expression to its intended meaning. Although prior work has proposed disambiguation-oriented
benchmarks probing the role of
vision, we observe that existing
benchmarks remain limited by task-format mismatch, narrow ambiguity coverage, or insufficient visual-dependency validation. Moreover, existing ambiguity evaluations are not well suited to diverse ambiguity types in open-ended translation. To address these limitations, we present VIDA (Visually-Dependent Ambiguity), a
dataset of 2,500 carefully curated instances in which resolving an annotated source span requires visual evidence. We further propose Disambiguation-Centric Metrics that use an LLM-as-a-judge classifier to verify whether annotated ambiguous expressions are resolved correctly at the span level. Evaluations with stronger recent LVLMs show that visual disambiguation remains challenging. Using chain-of-thought supervised fine-tuning as a diagnostic setting, we observe stronger out-of-distribution disambiguation than with SFT, with robust gains on collective-noun ambiguities and model-dependent gains on sentence-level ambiguities.
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All authors Jingheng Pan, Xintong Wang, Longyue Wang, Liang Ding, Weihua Luo, Chris Biemann
Computation and Language
Language models fail at extended rule following
Tianxiang Dai and Jonathan Fan
Large
language models are highly capable of answering difficult questions by retrieving, recombining, and attending to information in long contexts. For agentic tasks, an additional capability is required: the preservation of an exact state while repeatedly applying rules. We find that this reliability is absent across
language models. To demonstrate, we query 126 leading model variants with the task of counting a long string of repeated characters, and we find they all cannot accurately count above a model-dependent, syntax-sensitive counting capacity threshold. Failures are abrupt and persist even with increasing model size, inference time computation, and external tool. Mechanistic probing indicates that models use a finite number of internal states to mimic counting as a rule and fail once these states are exhausted. Furthermore, such states are the basis for performing complex tasks beyond counting. These results indicate that fundamentally new model architectures are required for autonomous
agents to achieve truly reliable rule following capabilities.
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Computation and Language
Enhancing Judgment Document Generation via Agentic Legal Information Collection and Rubric-Guided Optimization
Weihang Su, Xuanyi Chen, Yueyue Wu et al. (+2 more)
Automating the drafting of judgment documents is pivotal to judicial efficiency, yet it remains challenging due to the dual requirements of comprehensive
retrieval of legal information and rigorous logical
reasoning. Existing approaches, typically relying on standard
Retrieval-Augmented Generation and Supervised Fine-Tuning, often suffer from insufficient evidence recall, hallucinated statutory references, and logically flawed legal
reasoning. To bridge this gap, we propose Judge-R1, a unified framework designed to enhance LLM-based judgment document generation by jointly improving legal information collection and judgment document generation. First, we introduce Agentic Legal Information Collection, which employs a dynamic planning
agent to retrieve precise statutes and precedents from multiple sources. Second, we implement Rubric-Guided Optimization, a reinforcement learning phase utilizing Group Relative Policy Optimization (GRPO) with a comprehensive legal reward function to enforce adherence to judicial standards and
reasoning logic. Extensive experiments on the JuDGE
benchmark demonstrate that Judge-R1 significantly outperforms state-of-the-art baselines in both legal accuracy and generation quality.
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All authors Weihang Su, Xuanyi Chen, Yueyue Wu, Qingyao Ai, Yiqun Liu
Computation and Language
Learn-To-Learn on Arbitrary Textual Conditioning: A Hypernetwork-Driven Meta-Gated LLM
Luo Ji, Qi Qin, Ningyuan Xi et al. (+3 more)
Conventional LLMs may suffer from corpus heterogeneity and subtle condition changes. While finetuning can create the catastrophe forgetting issue, application of meta-learning on LLMs is also limited due to its complexity and scalability. In this paper, we activate the meta-signal of $\beta$ within the SwiGLU blocks, resulting in a meta-gating mechanism that adaptively adjusts the nonlinearity of FFN. A hypernetwork is employed which dynamically produces $\beta$ on textual conditions, providing meta-controllability on LLMs. By testing on different condition types such as task, domain, persona, and style, our method outperforms finetuning and meta-learning baselines, and can generalize reasonably on unseen tasks, condition types, or instructions. Our code can be found in https://github.com/AaronJi/MeGan.
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All authors Luo Ji, Qi Qin, Ningyuan Xi, Teng Chen, Qingqing Gu, Hongyan Li
Computation and Language · Cross-listed from cs.LG
Flexi-LoRA with Input-Adaptive Ranks: Efficient Finetuning for Speech and Reasoning Tasks
Zongqian Li, Yixuan Su, Han Zhou et al. (+2 more)
Parameter-efficient fine-tuning methods like Low-Rank Adaptation (LoRA) have become essential for deploying large
language models, yet their static parameter allocation remains suboptimal for inputs of varying complexity. We present Flexi-LoRA, a novel framework that dynamically adjusts LoRA ranks based on input complexity during both training and inference. Through empirical analysis across question answering, mathematical
reasoning, and
speech tasks, we demonstrate that maintaining consistency between training and inference dynamics is important for effective adaptation, particularly for sequential
reasoning tasks. Our findings reveal that input-dependent parameter allocation achieves higher performance with fewer parameters by optimally matching rank configurations to question complexity. Furthermore, task-specific dependency on rank dynamics varies, with mathematical
reasoning tasks exhibiting higher dependency than QA tasks. Successful adaptation manifests not only in correctness but also in
reasoning quality and instruction adherence. Flexi-LoRA consistently outperforms static LoRA while using fewer parameters, with performance gains more pronounced on tasks requiring strict
reasoning chains. Our approach realizes key benefits of mixture-of-experts frameworks through a more streamlined implementation, reducing parameter redundancy while improving model capabilities. We provide comprehensive empirical studies across diverse tasks, establishing a basis for future work in input-adaptive and efficient fine-tuning approaches.
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All authors Zongqian Li, Yixuan Su, Han Zhou, Zihao Fu, Nigel Collier
Computation and Language · Cross-listed from cs.HC
LLM-Augmented Semantic Steering of Text Embedding Projection Spaces
Wei Liu, Eric Krokos, Kirsten Whitley et al. (+2 more)
Low-dimensional projections of text
embeddings support visual analysis of document collections, but their spatial organization may not reflect the relationships an analyst intends to examine. Existing semantic interaction approaches encode semantic intent indirectly through
geometric constraints or model updates, limiting interpretability and flexibility. We introduce LLM-augmented semantic steering, which enables analysts to express semantic intent by grouping a small set of example documents within the projection. A large
language model externalizes this intent as natural-
language representations and selectively extends it to related documents; the resulting semantic information is then incorporated into document representations via text augmentation or
embedding-level blending, without retraining the underlying models. A case study illustrates how the same corpus can be reorganized from different semantic perspectives, while simulation-based evaluation shows that semantic steering improves global and local
alignment with target semantic structures using only minimal interaction.
Embedding-level blending further enables continuous and controllable steering of projection layouts. These results position projection spaces as intent-dependent semantic workspaces that can be reshaped through explicit, interpretable,
language-mediated interaction.
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All authors Wei Liu, Eric Krokos, Kirsten Whitley, Rebecca Faust, Chris North
Computation and Language · Cross-listed from cs.AI
MOIRA: Policy Memory and Belief Revision for Language-Model Agents in Non-Stationary Pair Trading
Polydoros Giannouris, Yuechen Jiang, Lingfei Qian et al. (+5 more)
Many sequential decision-making problems exhibit hierarchical structure, where high-level semantic choices constrain downstream actions and feedback is delayed and ambiguous. Learning in such settings is challenging due to credit assignment: performance degradation may arise from flawed abstractions, suboptimal execution, or their interaction. We study this challenge through pair trading, a domain that naturally combines long-horizon semantic
reasoning for asset pair selection with short-horizon execution under partial observability. We formulate pair trading as a hierarchical reinforcement learning problem and propose a
language-driven optimization framework in which both high-level and low-level policies are parameterized by large
language models (LLMs) and optimized exclusively through
prompt updates. Our approach leverages pretrained LLMs as hierarchical policies and uses trajectory- and episode-level textual feedback to adapt abstractions and execution without gradient-based fine-tuning. By explicitly separating abstraction selection from execution, the framework reduces non-stationarity across hierarchical levels and enables targeted adaptation under delayed feedback. Experiments on real-world
market data show consistent improvements over traditional and LLM-based baselines, demonstrating the effectiveness of
language-driven hierarchical reinforcement learning.
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All authors Polydoros Giannouris, Yuechen Jiang, Lingfei Qian, Yuyan Wang, Xueqing Peng, Jimin Huang, Guojun Xiong, Sophia Ananiadou
Computation and Language
StressEval: Failure-Driven Dynamic Benchmarking for Knowledge-Intensive Reasoning in Large Language Models
Yongrui Chen, Yangyang Ma, Xiaoying Huang et al. (+4 more)
Static
benchmarks for LLMs are increasingly compromised by contamination and overfitting especially on knowledge intensive
reasoning tasks While recent dynamic
benchmarks can alleviate staleness they often increase difficulty at the expense of answerability and controllability In this paper we propose StressEval a failure driven data synthesis framework that turns observed model failures into dynamic challenging and controllable test instances StressEval consists of three stages first it constructs a semi structured difficulty card that identifies the failed
reasoning step and its root cause second it applies a dual perspective instance synthesis method that targets both knowledge gaps and
reasoning breakdowns while preserving the underlying difficulty factors and third it applies a gating mechanism to retain only grounded unambiguous instances Seeding from multiple knowledge intensive
reasoning datasets we employ StressEval to build Dynamic OneEval a focused suite of challenging dynamic
benchmark Across several state of the art LLMs Dynamic OneEval yields substantially larger performance drops than the original
benchmarks while retaining explicit difficulty factors enabling more actionable iteration
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All authors Yongrui Chen, Yangyang Ma, Xiaoying Huang, Shenyu Zhang, Huajun Chen, Haofen Wang, Guilin Qi
Computation and Language · Cross-listed from cs.AI
A Language for Describing Agentic LLM Contexts
Noga Peleg Pelc, Gal A. Kaminka and Yoav Goldberg
Large
language models are increasingly used within larger systems ("LLM
agents"). These make a sequence of LLM calls, each call providing the LLM with a combination of instructions, observations, and interaction history. The design of the encoded information and its structure play a central role in the quality of the resulting system, leading to efforts spent on context engineering. It is therefore critical to communicate the composition of the LLM context in a system, and how it evolves over time. Yet, no standard exists for doing so: context construction is typically conveyed through informal prose, ad hoc diagrams, or direct inspection of code, none of which precisely capture how a
prompt evolves across interaction steps or how two context representation strategies differ. To remedy this, we introduce the Agentic Context Description
Language (ACDL), a
language for specifying the structure and dynamics of LLM input contexts in a precise, readable, and standard manner, along with visualizations. ACDL provides constructs for specifying context aspects such as role message sequences, dynamic content, time-indexed references, and conditional or iterative structure, capturing the full architecture of a
prompt independently of any particular implementation. ACDL diagrams can be hand drawn on a whiteboard, or written in formal
language which can then be rendered. We describe the
language, demonstrate it by documenting several existing systems and their variants, and encourage the community to adopt it for describing LLM systems context, both in day-to-day communication and in papers. Tooling, examples and documentation are available at www.acdlang.org.
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Computation and Language · Cross-listed from cs.LG
RefusalGuard: Geometry-Preserving Fine-Tuning for Safety in LLMs
Sadia Asif and Mohammad Mohammadi Amiri
Fine-tuning safety-aligned
language models for downstream tasks often leads to substantial degradation of refusal behavior, making models vulnerable to
adversarial misuse. While prior work has shown that safety-relevant features are encoded in structured representations within the model's activation space, how these representations change during fine-tuning and why
alignment degrades remains poorly understood. In this work, we investigate the representation-level mechanisms underlying
alignment degradation. Our analysis shows that standard fine-tuning induces systematic drift in safety-relevant representations, distorts their
geometric structure, and introduces interference between task optimization and safety features. These effects collectively lead to increased harmful compliance. Motivated by these findings, we introduce REFUSALGUARD, a representation-level fine-tuning framework that preserves safety-relevant structure during model adaptation. Our approach constrains updates in hidden representation space, ensuring that safety-mediating components remain stable while allowing task-specific learning in complementary directions. We evaluate REFUSALGUARD across multiple model families, including LLaMA, Gemma, and Qwen, on
adversarial safety
benchmarks such as AdvBench, DirectHarm4, and JailbreakBench, as well as downstream utility tasks. Our approach achieves attack success rates comparable to base safety-aligned models while maintaining competitive task performance, significantly outperforming baselines.
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Computation and Language · Cross-listed from cs.SD
Spoken Language Identification with Pre-trained Models and Margin Loss
Zhihua Fang, Liang He and Weiwu Jiang
For the speaker-controlled spoken
language identification task proposed in the TidyLang Challenge 2026, this paper proposes a
language identification method based on pre-trained models and margin-based losses. The proposed method adopts a pre-trained ECAPA-TDNN as the feature encoder and incorporates margin-based losses to enhance the discriminative ability of
language representations, thereby improving inter-class separability and reducing the interference of non-linguistic factors such as speaker characteristics. Experimental results on the Tidy-X
dataset show that the proposed method achieves 85.95% macro accuracy and 90.96% micro accuracy on the
language identification task and 17.08% equal error rate (EER) on the verification task. Compared with the official baseline, the macro accuracy improves by 45.7%, the micro accuracy improves by 15.2%, and the EER is reduced by approximately 50.8%, demonstrating the effectiveness of the proposed method. The code will be released at https://github.com/PunkMale/TidyLang2026.
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Computation and Language
Maistros: A Greek Large Language Model Adapted Through Knowledge Distillation From Large Reasoning Models
Nikolaos Giarelis, Charalampos Mastrokostas and Nikos Karacapilidis
Large
Language Models (LLMs) have substantially advanced the field of Natural
Language Processing (NLP), achieving state-of-the-art performance across a wide range of tasks. These improvements have been attributed, in part, to their emerging
reasoning capabilities, which are enabled by large-scale training and increased model capacity. However, existing LLMs can generate erroneous responses when addressing complex queries that fall outside their training distribution, due to limited internal knowledge or the need for multi-step
reasoning. To address these limitations, recent work has introduced large
reasoning models (LRMs), which incorporate explicit internal
reasoning processes to improve response accuracy. Additionally, state-of-the-art LRMs often comprise hundreds of billions of parameters and require several seconds per inference, even on advanced multi-GPU systems. These characteristics limit their practicality for deployment in conventional computing environments. Meanwhile, NLP research on
multilingual LLMs continues to prioritize high-resource
languages. However, these models exhibit limited performance in under-resourced
languages, primarily due to insufficient
language- and culture-specific training data. In this paper, we focus on Modern Greek, for which only a limited number of question answering (QA)
datasets have been proposed, most of which are intended for model evaluation. To address this research gap in Greek QA, we make the following contributions: (i) CulturaQA, a high-quality LRM-generated and human-curated
dataset, for Greek LLM training and evaluation; (ii) a
memory-efficient LLM evaluation framework adaptable to diverse
languages and QA tasks; (iii) Maistros 8B, a state-of-the-art open-weights Greek LLM developed via knowledge
distillation and fine-tuning on CulturaQA; and (iv) a comprehensive evaluation of nine LLMs across nine human-curated Greek QA
datasets.
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Computation and Language
Spatiotemporal Hidden-State Dynamics as a Signature of Internal Reasoning in Large Language Models
Kotaro Furuya and Takahito Tanimura
Large
reasoning models (LRMs) generate extended solutions, yet it remains unclear whether these traces reflect substantive internal computation or merely verbosity and overthinking. Although recent hidden-state analyses suggest that internal representations carry correctness-related signals, their coarse aggregations may obscure the
token and layer structure underlying
reasoning computation. We investigate hidden-state transitions across decoding steps and layers, and identify a distinct spatiotemporal pattern in LRMs: successful trajectories exhibit broad temporal dynamics with localized layer-wise concentration, while this structure is weaker in non-
reasoning models and knowledge-heavy domains. We formalize this characteristic as Spatiotemporal Amplitude of Latent Transition (StALT), a training-free trajectory statistic that summarizes temporal changes between adjacent
tokens weighted by within-
token layer saliency. Across diverse models and
benchmarks, StALT reliably separates correct from incorrect trajectories in
reasoning-intensive regimes, providing a competitive label-free correctness signal alongside strong output-space and length-based baselines. Intervention analyses further show that this spatiotemporal amplitude responds systematically to manipulations that increase or reduce the demand for internal
reasoning, supporting its association with latent
reasoning dynamics in LRMs. These findings provide empirical evidence that LRMs exhibit measurable hidden-state dynamics and offer a practical probe for understanding internal computation beyond output-based evaluation.
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Computation and Language
Do Large Language Models Plan Answer Positions? Position Bias in Multiple-Choice Question Generation
Xuemei Tang, Xufeng Duan and Zhenguang G. Cai
Large
language models (LLMs) are increasingly used to generate multiple-choice questions (MCQs), where correct answers should ideally be uniformly distributed across options. However, we observe that LLMs exhibit systematic position biases during generation. Through extensive experiments with 10 LLMs and 5
vision-
language models (VLMs) on three MCQ generation tasks, we show that these biases are structured, with similar patterns emerging within model families. To investigate the underlying mechanisms, we conduct probing experiments and find that hidden representations in the question stem encode predictive signals of the correct answer position, suggesting that answer position may be implicitly planned during generation. Building on this insight, we apply activation steering to manipulate internal representations and influence answer position. Our results show that steering can partially control positional preferences and substantially shift answer position distributions. Our findings provide a practical framework for studying implicit positional planning in LLMs and highlight the importance of controllable generation for reliable MCQ construction and evaluation.
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Computation and Language
The Cylindrical Representation Hypothesis for Language Model Steering
Lang Gao, Jinghui Zhang, Wei Liu et al. (+7 more)
Steering is a widely used technique for controlling large
language models, yet its effects are often unstable and hard to predict. Existing theoretical accounts are largely based on the Linear Representation Hypothesis (LRH). While LRH assumes that concepts can be orthogonalized for lossless control, this idealized mapping fails in real representations and cannot account for the observed unpredictability of steering. By relaxing LRH's orthogonality assumption while preserving linear representations, we show that overlapping concept contributions naturally yield a sample-specific axis-orthogonal structure. We formalize this as the Cylindrical Representation Hypothesis (CRH). In CRH, a central axis captures the main difference between concept absence and presence and drives concept generation. A surrounding normal plane controls steering sensitivity by determining how easily the axis can activate the target concept. Within this plane, only specific sensitive sectors strongly facilitate concept activation, while other sectors can suppress or delay it. While the surrounding normal plane can be reliably identified from difference vectors, the sensitive sector cannot, introducing intrinsic uncertainty at the sector level. This uncertainty provides a principled explanation for why steering outcomes often fluctuate even when using well-aligned directions. Our experiments verify the existence of the cylindrical structure and demonstrate that CRH provides a valid and practical way to interpret model steering behavior in real settings: https://github.com/mbzuai-nlp/CRH.
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All authors Lang Gao, Jinghui Zhang, Wei Liu, Fengxian Ji, Chenxi Wang, Zirui Song, Akash Ghosh, Youssef Mohamed, Preslav Nakov, Xiuying Chen
Computation and Language
RMGAP: Benchmarking the Generalization of Reward Models across Diverse Preferences
Yangyang Zhou and Yi-Chen Li
Reinforcement Learning from Human Feedback has become the standard paradigm for
language model
alignment, where reward models directly determine
alignment effectiveness. In this work, we focus on how to evaluate the generalizability of reward models. By "generalizability", we mean the ability of RMs to correctly rank responses to align with diverse user preferences. However, existing reward model
benchmarks are typically designed around a universal preference, failing to assess this generalization. To address this critical gap, we introduce RMGAP, a
benchmark comprising 1,097 instances across Chat, Writing,
Reasoning, and Safety domains. Since different users exhibit diverse preferences for the same task, we first generate four distinct responses with different linguistic profiles for each collected
prompt. However, the original
prompt set lacks the specificity to convey different preferences. We therefore construct tailored
prompts by contrasting these candidates and designing scenarios in which one response becomes the uniquely appropriate choice. Moreover, we observe that users often express the same preference using different phrasings, and thus extend each
prompt with two paraphrased variants. Our evaluation of 24 state-of-the-art RMs reveals their substantial limitations: even the best RM achieves only 49.27% Best-of-N accuracy, highlighting considerable room for improvement in reward model generalization. Related data and code are available at https://github.com/nanzhi84/RMGAP.
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Computation and Language
The Compliance Gap: Why AI Systems Promise to Follow Process Instructions but Don't
Kwan Soo Shin
An auditor instructs an AI assistant: "open each file individually using the Read tool – no scripts, no
agents." The AI replies "Yes" – then issues a single batched call summarizing all fifty files at once. We call this the Compliance Gap: a third, orthogonal axis of AI honesty distinct from factual truthfulness and rhetorical substance. Three questions: does this verbal-behavioral disconnect exist (existence); can any text-only observer recover it (detectability); what infrastructure does AI deployment need (remedy)? Some 75
benchmarks (IFEval, SWE-bench, BFCL, COMPASS, SpecEval) measure outcome fidelity; none measures process fidelity.
Theorem 1 shows the gap is structurally inevitable under RL that rewards text without observing behavior.
Theorem 2, via the Data Processing Inequality, shows it is undetectable from text alone – by any human or LLM observer, present or future. Thirteen experiments and 2,031 sessions on six frontier models confirm both predictions. Under default framing, all six exhibit instruction compliance rates of 0% – Claude Sonnet 4 verbally agrees ten out of ten times then bypasses in all ten. The gap is selective: 97% compliance where rationale is rewarded (audit trails), 0-4% where it is not (file reading,
privacy masking); removing delegation tools raises compliance to 75% (Cohen's d = 2.47), confirming environmental affordance rather than weight-encoded failure. Nine blinded human raters achieve Fleiss' kappa = 0.130 and correctly identify zero of fifteen compliant sessions, exactly as
Theorem 2 predicts. Where humans show 47% intention-behavior gaps in psychology and 96.5pp gaps in
surgical audits, RLHF-trained models approach 100% under default conditions – a regime warranting its own measurement infrastructure. We release BS-Bench: the first open
benchmark for process compliance, with seven tool-call-log audit metrics and a public leaderboard.
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Computation and Language
Only Say What You Know: Calibration-Aware Generation for Long-Form Factuality
Wen Luo, Guangyue Peng, Liang Wang et al. (+7 more)
Large
Reasoning Models achieve strong performance on complex tasks but remain prone to
hallucinations, particularly in long-form generation where errors compound across
reasoning steps. Existing approaches to improving factuality, including abstention and factuality-driven optimization, follow a coupled exploration-commitment paradigm, in which intermediate
reasoning is unconditionally propagated to the final output, limiting fine-grained control over information selection and integration. In this paper, we propose an Exploration-Commitment Decoupling paradigm that disentangles knowledge exploration from final commitment, enabling models to explore with awareness while answering cautiously. We instantiate the paradigm with Calibration-Aware Generation (CAG), a framework that equips models with end-to-end, calibration-aware generation capabilities, by augmenting intermediate
reasoning with calibrated reliability estimates and prioritizing reliable content in final outputs. Across five long-form factuality
benchmarks and multiple model families, CAG improves factuality by up to 13%, while reducing decoding time by up to 37%. Overall, our work highlights decoupling as a principled approach for more reliable long-form generation, offering directions for trustworthy and self-aware generative systems.
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All authors Wen Luo, Guangyue Peng, Liang Wang, Nan Yang, Wei Li, Yuhan Song, Shaohang Wei, Feifan Song, Furu Wei, Houfeng Wang
Computation and Language · Cross-listed from cs.AI
NH-CROP: Robust Pricing for Governed Language Data Assets under Cost Uncertainty
Xu Zheng, Feiyu Wu, Zhuocheng Wang et al. (+2 more)
Language data are increasingly acquired and governed as assets, yet platforms often price candidate resources before knowing their true
privacy or access costs. We study online pricing for governed
language data assets under cost uncertainty. At each round, a platform observes an NLP task, a candidate asset, and a coarse cost estimate, may pay for a refined cost signal, posts a price, and receives safe net revenue. We introduce NH-CROP, a clipped robust pricing framework with a no-harm information-acquisition gate. The method compares direct pricing, risk-aware pricing, and verify-then-price, and acquires information only when its estimated decision value exceeds the best no-verification alternative. Across synthetic, real-proxy, and downstream-utility-grounded
benchmarks, clipped NH-CROP variants improve or remain competitive with price-only and risk-aware baselines. Causal ablations show that paid verification is not the main source of gains in real-proxy and utility-grounded settings: the strongest learned policies often choose not to verify. Oracle and high-decision-value diagnostics show that refined cost information can still have substantial local value. Overall, governed
language-data platforms should calibrate pricing under uncertain access costs first and verify only when information is cheap and decision-actionable.
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All authors Xu Zheng, Feiyu Wu, Zhuocheng Wang, Yiming Dai, Hui Li
Computation and Language
Less is More: Geometric Unlearning for LLMs with Minimal Data Disclosure
Chenchen Tan, Xinghao Li, Shujie Cui et al. (+3 more)
As large
language models (LLMs) are increasingly deployed in real-world systems, they must support post-hoc removal of specific content to meet
privacy and governance requirements. This motivates selective unlearning, which suppresses information about a particular entity or topic while preserving the LLM's general utility. However, most existing LLM unlearning methods require access to the original training corpus and rely on output-level refusal tuning or broad gradient updates, creating a tension among unlearning strength, non-target preservation, and data availability. We propose
Geometric Unlearning (GU), an approach that operates directly on the model's
prompt-conditioned hidden states without access to the original training corpus. Specifically, GU distills a compact, low-rank safe-behavior subspace from a small set of safe reference
prompts and uses lightweight anchor-in-context synthetic
prompts to trigger localized, projection-based
alignment of hidden representations to this safe subspace. A teacher-
distillation regularizer on synthetic non-target anchors further reduces collateral drift. Across
privacy-oriented unlearning
benchmarks (ToFU and UnlearnPII), GU achieves strong target suppression with minimal impact on non-target performance, demonstrating that effective unlearning can be achieved with minimal synthetic data.
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All authors Chenchen Tan, Xinghao Li, Shujie Cui, Youyang Qu, Cunjian Chen, Longxiang Gao
Computation and Language
EGAD: Entropy-Guided Adaptive Distillation for Token-Level Knowledge Transfer
Hao Zhang, Zhibin Zhang, Guangxin Wu et al. (+3 more)
Large
language models (LLMs) have achieved remarkable performance across diverse domains, yet their enormous computational and
memory requirements hinder deployment in resource-constrained environments. Knowledge
distillation offers a promising solution by transferring knowledge from a large teacher model to a smaller student model. However, existing
distillation methods typically treat all
tokens equally, ignoring the fact that different
tokens contribute unequally to model decisions. This can lead to inefficient knowledge transfer and reduced learning effectiveness. To address this limitation, we propose an
entropy-based adaptive
distillation strategy that dynamically adjusts the training process at the
token level. Our method leverages the teacher's output
entropy to guide three aspects of
distillation. Specifically, we introduce a
token-level curriculum by dynamically shifting focus from low- to high-
entropy tokens during training. We further adjust the
distillation temperature based on
token entropy to better capture teacher confidence patterns. Moreover, we employ a dual-branch architecture for efficient logits-only
distillation on easy
tokens and deeper feature-based
distillation on difficult
tokens. Extensive experiments validate the soundness and effectiveness of our method.
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All authors Hao Zhang, Zhibin Zhang, Guangxin Wu, Wanyi Ning, Jiafeng Guo, Xueqi Cheng
Computation and Language · Cross-listed from cs.CV
SignVerse-2M: A Two-Million-Clip Pose-Native Universe of 55+ Sign Languages
Sen Fang, Hongbin Zhong, Yanxin Zhang et al. (+2 more)
Large-scale sign
language resources usually pair RGB
videos with text and support recognition, translation, and generation. However, RGB frames contain backgrounds, clothing, and other appearance information unrelated to signing motion. Representing the
videos as whole-body keypoints such as DWPose removes much of this variation, produces a compact description of body, hand, and facial movement, and matches the input used by recent pose-guided
video models. Existing
datasets do not provide this representation at scale for in-the-wild sign
language videos. We present SignVerse-2M, a
multilingual dataset containing approximately two million pose clips from more than 55 sign
languages. We process publicly available sign
language videos with a shared DWPose pipeline, representing body, hand, and facial motion in the same keypoint format across all clips. The source
videos include diverse signers, viewpoints, and recording environments. We also release the processing pipeline, task definitions, and SignDW
Transformer baselines. Experiments show that the data supports
multilingual text-to-pose modeling and that the generated poses can directly drive several recent pose-conditioned rendering systems.
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All authors Sen Fang, Hongbin Zhong, Yanxin Zhang, Liwei Che, Dimitris N. Metaxas
Computation and Language
TCDA: Thread-Constrained Discourse-Aware Modeling for Conversational Sentiment Quadruple Analysis
Xinran Li, Xinze Che, Yifan Lyu et al. (+2 more)
Conversational Aspect-based Sentiment Quadruple Analysis (DiaASQ) needs to capture the complex interrelationships in multiple rounds of dialogues. Existing methods usually employ simple Graph Convolutional Networks (GCN), which introduce structural noise and fail to consider the temporal sequence of the dialogues, or use standard RoPE, which implicitly captures relative distances in a flat sequence but cannot clearly separate the
token-level syntactic order from the utterance-level progression, and may suffer from the Distance Dilution problem. To address these issues, we propose a new framework that combines Thread-Constrained Directed Acyclic Graph (TC-DAG) and Discourse-Aware Rotary Position
Embedding (D-RoPE). Specifically, TC-DAG filters out cross-thread noise based on thread constraints, maintains global connectivity through root anchoring, and incorporates the temporal sequence of the dialogues. D-RoPE aligns multi-layer semantics using dual-stream projection and multi-scale frequency signals, captures thread dependencies using tree-like distances, and alleviates the
token-level Distance Dilution problem by incorporating utterance-level progressions. Experimental results on two
benchmark datasets demonstrate that our framework achieves state-of-the-art performance.
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All authors Xinran Li, Xinze Che, Yifan Lyu, Zhiqi Huang, Xiujuan Xu
Computation and Language
The Reasoning Trap: An Information-Theoretic Bound on Closed-System Multi-Step LLM Reasoning
Kwan Soo Shin
When copies of the same
language model are prompted to debate, they produce diverse phrasings of one perspective rather than diverse perspectives. Multi-
agent debate (MAD), and more broadly closed-system
reasoning where
agents iteratively transform each other's outputs, tends to preserve answer accuracy while degrading the
reasoning behind those answers. We name the multi-
agent case the Debate Trap and the broader phenomenon the
Reasoning Trap, offering a programmatic theory of evidence-grounded
reasoning failure.The framework has three parts: (i) SFS (Supported Faithfulness Score), a claim-level metric verifying decomposed atomic claims against provided evidence (decomposer-invariant rankings: Spearman rho=1.0); (ii) EGSR (Evidence-Grounded Socratic
Reasoning), replacing
adversarial argumentation with evidence-grounded inquiry; (iii)
Theorem 1 (DPI Bound): under standard MAD, the chain E -> O^0 -> O^1 -> ... is Markov, and the Data Processing Inequality implies E[I(E;O^{t+1})] <= E[I(E;O^t)]. Three companion results – open-system recovery (
Theorem 2), EGSR accumulation (Lemma 2), and vote-aggregation floor (Proposition 1) – partition multi-step LLM
reasoning by its information-theoretic relationship to E. Across 16 conditions on SciFact (300 claims) and FEVER (1,000 claims), DebateCV (C13) preserves 88% of baseline accuracy while SFS drops 43%; majority-vote MAD (C15) reduces SFS to 1.7% of baseline (p < 10^{-6}, d = -0.96); EGSR recovers 98%. An R6 cohort study (Korean n=10x30 FEVER; English n=3x200 SciFact) finds inter-rater Fleiss kappa <= +0.018 with 0.8-1.4 Likert intra-rater shifts across
language and domain – the human agreement that faithfulness metrics have been calibrated against is not itself stable. We offer one falsifiable
conjecture: any closed-system
reasoning protocol preserving
Theorem 1's Markov structure is, in expectation, subject to the same DPI bound.
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