Computation and Language
Rubric Spans are Label Representations: Joint LLM Encoding for Short Answer Scoring
Zhifan Sun, Sebastian Gombert, Fabian Zehner et al. (+3 more)
Automatic Short Answer Scoring (ASAS) requires models that can score student responses against question-specific criteria while remaining efficient and transferable across rubric sets. We propose RUSPAN, a rubric-conditioned ASAS framework that treats rubric descriptions as semantic label representations. RUSPAN serialises the question context, student answer, and all candidate rubric levels into a single sequence, then scores the levels listwise from the rubric-span and whole-sequence representations produced in a single LM pass. We further introduce RUSPAN-RIM, in which a Rubric-Independent Mask prevents rubric spans from attending to one another, making rubric representations depend only on the answer and question context and preventing overfitting to rubric patterns during training for zero-shot transfer. On six ASAS
benchmarks spanning English, German, and Portuguese, RUSPAN improves mono-
benchmark scoring over discriminative and generative baselines, while RIM with position reindexing delivers consistent and substantial gains on PT-ASAG, the held-out
benchmark with the strongest combined
language and rubric-structure shift.
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All authors Zhifan Sun, Sebastian Gombert, Fabian Zehner, Leon Camus, Longwei Cong, Hendrik Drachsler
Computation and Language · Cross-listed from cs.LG
When Rank Rises as LLMs Degrade
Zhaohui Geoffrey Wang
Post-training adapts
language models in non-stationary environments. Practitioners monitor representation health with RankMe and related spectral statistics, often assuming that rank falls when representations degrade. We show that this assumption is unsafe for LLM post-training. In a controlled study of Qwen3-0.6B with four degradation modes and three seeds, data duplication worsens held-out loss by 75% relative to healthy while increasing both original and centred RankMe; the latter changes by 13.5 pooled standard deviations. Covariance effective rank rises to nearly twice its healthy value. This failure is spectral dispersion rather than collapse, so a one-sided monitor rates the worst checkpoint as the healthiest. By contrast, a learning-rate misconfiguration lowers centred RankMe and k95, while uncentred RankMe is inconsistent across seeds. Direction is therefore a property of the regime-statistic pair and cannot be fixed by recalibration alone. We also distinguish two often-conflated statistics: RankMe normalises singular values, whereas covariance effective rank normalises
eigenvalues. On raw intermediate-layer states in the pretrained model, massive activations pin the latter near 1 out of dimension d while RankMe retains usable range. We then test a two-sided, multichannel sequential monitor with separate calibration and test data. In a pre-registered shared-prefix, leave-one-seed-out evaluation, it detects all three damage regimes in every fold 10 to 60 steps after the fork and separates dispersion from downward-rank damage by firing direction. However, it never precedes held-out probe loss, and calibration with two seeds produces false alarms on the held-out healthy seed. Spectral monitoring can diagnose failure regimes, but it does not warn earlier than held-out loss, and validity claims require held-out healthy data.
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Computation and Language
On-Policy Distillation Teaches New Skills but Not New Knowledge
Yixuan Tang and Yi Yang
On-policy
distillation (OPD) strengthens
language-model
reasoning, yet whether students acquire new factual knowledge or compositional skill for multi-step
reasoning remains unknown. We separate these capabilities using a controlled synthetic framework that measures the student's initial capabilities and independently controls the teacher's additional facts, compositional skill, or both. Across four models from three families, reverse-KL OPD reliably transfers compositional skill across unseen
reasoning structures, but transfers minimal factual knowledge. Decoupling the
distillation recipe reveals the source of this asymmetry: replacing reverse KL with forward KL restores factual transfer, whereas student rollouts specifically improve the execution of multi-step
reasoning. Experiments on recent factual QA and competition mathematics show a similar asymmetry under reverse-KL OPD, yielding notable
reasoning gains without factual
memory expansion. Together, these results demonstrate that on-policy
distillation does not expand a model's parametric knowledge, but instead teaches it to organize and compose the knowledge it already possesses.
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Computation and Language · Cross-listed from cs.LG
Coding-Agent Benchmarks Should Match Their Users' Task Flows
Igor Slinko, Yaroslav Golubev and Sergey Titov
The evaluation of coding
agents generally strives to be as realistic as possible. In our study, we collect 4,782
agent sessions of real software engineers in JetBrains IDEs, which we call Production Sessions. Since our subject is interactive
agents, we study the sessions with at least three user messages (33% of the sample). These long sessions differ from issue-derived
benchmark tasks in two ways: (i) user requests span a far wider mix of task types - questions about the project's code, planning, review, refactoring, execution - and (ii) users switch between types throughout a session. Long-session samples from three public interaction corpora exhibit markedly different Task Flows (the distributions of session lengths, task types, and type-to-type transitions), so no single interaction distribution is universally realistic:
benchmarks should name a target use case and calibrate to measurements from it. We present SWE-TaskFlow, an approach for transforming any issue-derived
benchmark: it preserves the verified tasks and tests while steering the interaction toward a target Task Flow through
prompt splitting and verifiable repository QA, with a TaskFlow
Alignment Score (TFAS) for selecting among generated trajectories. In a pilot on 700 SWE-Bench Pro tasks, solving the task sequentially in several steps approximately doubles
agent cost without a stable change in resolve rate: the interaction protocol itself is an important dimension of evaluation.
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Computation and Language
Which Language Should a Skeleton Speak? Language Choices in Multilingual Reasoning
HyeonSeok Lim, SeungWoo Song, Inho Won et al. (+3 more)
Skeleton-based
reasoning prompting is a promising training-free approach for structuring LLM
reasoning, but prior work largely assumes an English-centric setting. We propose the
Language-Aware Skeleton Exploration Framework (LASEF) to study skeleton-
language choice in multilingual mathematical
reasoning. Across math
benchmarks, model scales, and
languages, we show that English skeletons yield a small positive tendency on average, most visible for smaller models and low-resource
languages. However, few
language-level gains remain significant after correction, and English is not universally optimal. Combining greedy decoding, multi-rollout evaluation, translation ablation, and cross-
benchmark validation, we further find three patterns of skeleton-
language effects: directionally consistent, evaluation- and
benchmark-dependent, and asymmetric negative. These effects cannot be fully explained by generation quality alone. Overall, skeleton
language is a context-dependent design variable that requires multi-level exploration. All resources are released at https://github.com/lhsstn/LASEF.
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All authors HyeonSeok Lim, SeungWoo Song, Inho Won, Hoyun Song, Jihyo Kim, KyungTae Lim
Computation and Language · Cross-listed from cs.LG
Collaborative Reasoning Distillation via Cross-Feedback and Coherent Curation
Taehoon Kim, Seunggeun Cho and Dongsu Han
Reasoning capabilities are critical for advancing Large
Language Models, yet current approaches either require massive computational budgets or struggle to effectively distill
reasoning to smaller models. Standard
distillation methods rely on outcome-based rewards, failing to distinguish between sound
reasoning and lucky guesses. We propose Collaborative
Reasoning Distillation (CRD), a framework that enhances
reasoning in compact models through three innovations: (1) interactive cross-feedback where teachers iteratively critique each other's
reasoning, (2) fine-grained step-wise quality assessment capturing logical validity independent of final answers, and (3) coherence-aware step stitching that synthesizes complementary strengths. Students are trained via
Reasoning Quality Optimization (RQO) with budget constraints. Our model, CRD-4B, achieves 97.3% on MATH-500 and 70.3% on AIME'25, surpassing baselines while using only 50K training examples, up to 12 times smaller than the
datasets of comparable models.
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Computation and Language
How Do LLMs Change Predictions Under Negation?
Jongwook Yoon, Jongwon Lim, Sungjib Lim et al. (+2 more)
Negation is an essential feature of human
language, yet large
language models (LLMs) remain unreliable in processing it. We evaluate recent open-source and closed-source LLMs on our negation
benchmark and find that, in 37-71% of cases, they repeat the same answer under negation (e.g., "Madrid" for "What is not the capital of Spain?"). To understand and address this brittleness, we mechanistically examine how models operate under negation. Our main finding is that specialized
attention heads and MLP
neurons jointly implement negation by (1) suppressing
retrieval of the original answer (e.g., "Madrid") while (2) promoting a favored candidate within the answer category (e.g., "Paris"). This contrasts with accounts of human negation processing, in which information about the original answer helps to determine what should be excluded. Furthermore, we find that this difference from human processing is a key source of negation failures: the model's mechanism relies on suppressing the original answer rather than using it to determine what to exclude, so the model can repeat the original answer when suppression is too weak or when a bias toward particular answers prevents it from selecting an alternative. To address this weakness in the model's negation mechanism, we propose a training objective that requires larger shifts in answer preference for more confident original predictions, and show that it reduces negation failures with less degradation of general capabilities than standard fine-tuning baselines. Together, our results demonstrate how mechanistic analysis can reveal why a linguistic capability fails and guide training that targets the underlying limitation.
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All authors Jongwook Yoon, Jongwon Lim, Sungjib Lim, Woojin Cho, Yohan Jo
Computation and Language
RELATE: An Evaluation Framework for measuring Relational Orientation of Large Language Models
Shivam Shukla, Jihye Kim, Shubham Gaur et al. (+2 more)
Large
language models (LLMs) are increasingly used for emotional support, raising concern that sustained use may draw users away from their real-world relationships. Yet existing evaluations primarily focus on the safety, empathy, or helpfulness of responses, leaving under-examined a relational question: where does the model orient the user for continued support? To address this question, we introduce relational orientation, a property operationalized through two non-exclusive dimensions: inward-facing (IF)
language, which positions the AI as the user's ongoing source of support, and outward-scaffolding (OS)
language, which encourages real-world human connection. Grounded in psychological and sociological literature, we formalize a taxonomy of relational orientation and present RELATE, a persona-conditioned framework for measuring inward-facing and outward-scaffolding
language at the sentence level in multi-turn dialogues. RELATE pairs 76 help-seeking situations adapted from naturally occurring questions with three simulated user styles, providing 228 evaluation stimuli. In our experiments, we evaluate seven LLMs using dialogues with six assistant turns each, yielding 1,596 dialogues and 69,194 assistant sentences. We assess these sentences using a primary rubric-based LLM judge and apply a secondary judge to a subset. Under automated evaluation, we find that the proportion of sentences labeled as IF is higher at the sixth assistant turn than at the first, while the proportion labeled as OS is substantially lower for hesitant, indirect simulated users than for explicit, reassurance-seeking users. RELATE provides a reproducible framework and a sentence-level signal for auditing and steering the relational orientation of supportive LLMs.
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All authors Shivam Shukla, Jihye Kim, Shubham Gaur, Mahnaz Roshanaei, Magy Seif El-Nasr
Computation and Language · Cross-listed from cs.CR
Constitution-Guided Watermarking
Toluwani Aremu, Samuele Poppi and Nils Lukas
Watermarking enables
language model providers to identify text generated by their models. However, its desired properties can conflict (\ie~stronger watermark signals can degrade text quality), while designs that resist editing may also facilitate forgery. Providers address these trade-offs by choosing configurations that balance competing objectives or prioritize particular properties. Either approach imposes a shared operating point on requests with different requirements, potentially sacrificing quality where wording preservation matters or robustness where reliable attribution is essential. To allow flexible and adaptable designs, we introduce Constitution-Guided Watermarking, a framework that selects request-appropriate trade-offs from provider requirements, listed as natural-
language principles. Offline, a pretrained
reasoning agent examines constitutional rules alongside watermark implementations and iteratively refines rule-specific configurations using empirical feedback. At deployment, a separate monitor identifies applicable rules and retrieves the corresponding policy, including watermarking exemptions, without modifying the serving model. Furthermore, our framework supports offline parallel optimization and refinement of rule-specific configurations based on evolving provider requirements without affecting deployment, and binds each deployed configuration to its evaluation evidence, making deployment decisions auditable. In a proof-of-concept evaluation using KGW and a five-rule constitution, our framework selects configurations responsive to provider priorities and improves post-paraphrase detection on robustness-prioritized requests by up to $14$ percentage points over fixed configurations, while matching or exceeding all baselines in aggregate quality and clean detection at a nominal $0.1\%$ false-positive rate.
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Computation and Language · Cross-listed from stat.ML
Certified by Abstention: Distribution-Free Guarantees for Chain-of-Thought Verifiers at Small Calibration Budgets
Arjun Balaji
Signals that predict whether a chain-of-thought (CoT) trace is correct are compared by AUC, but deploying one requires a threshold with a guarantee. We ask what distribution-free selective guarantees deliver for CoT verifiers at realistic calibration budgets of tens to a few hundred labelled problems, using seven open models, five verifier signals and 37,000 graded traces. The central observation is validity by abstention: an $(\alpha,\delta)$-valid procedure that issues a certificate with probability $P_{\rm fire}$ bounds the failure probability of an issued certificate only by $\delta/P_{\rm fire}$, so a certificate that rarely fires can be valid and wrong every time it is used. In a simulation with known risk the standard certificate fails in at most 0.3% of calibration draws but in up to 69% of those in which it fires. A certification floor and a
lattice condition for Benjamini-Hochberg conformal selection explain why certificates abstain at these budgets, and the data bear them out: the standard certificate returns nothing or a large accepted set, and an unreadable residual-stream probe buys two to three times the coverage of the readable signals, an edge a cross-fitted reconstruction cannot recover linearly from the readable features. We then give a floor-started fixed-sequence certificate, valid without monotonicity assumptions, that covers more than the Bonferroni certificate on every model-signal pair and raises coverage at the non-vacuous target $0.75\pi_0$ from 0.05 to 0.16, although the floor keeps absolute coverage small. Finally, a certificate cannot see what matters after deployment: under
benchmark shift the error among accepted traces tracks the new task's base error, and under best-of-$n$ selection against the verifier it rises past the target while the empirical failure frequency stays below $\delta$, because abstention absorbs the failures.
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Computation and Language
A Comparative Study of Evaluation Metrics for Long-Document Financial Narrative Summarization with Transformers
Nadhem Zmandar, Mo El-Haj and Paul Rayson
There are more than 2,000 listed companies on the UK's London Stock Exchange, divided into 11 sectors who are required to communicate their financial results at least twice in a single financial year. UK annual reports are very lengthy documents with around 80 pages on average. In this study, we aim to
benchmark a variety of summarisation methods on a set of different pre-trained
transformers with different extraction techniques. In addition, we considered multiple evaluation metrics in order to investigate their differing behaviour and applicability on a
dataset from the Financial Narrative Summarisation (FNS 2020) shared task, which is composed of annual reports published by firms listed on the London Stock Exchange and their corresponding summaries. We hypothesise that some evaluation metrics do not reflect true summarisation ability and propose a novel BRUGEscore metric, as the harmonic mean of ROUGE-2 and BERTscore. Finally, we perform a statistical significance test on our results to verify whether they are statistically robust, alongside an
adversarial analysis task with three different corruption methods.
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Computation and Language
Goldsmith: Gold-Loss-Guided Definition Optimization with an Agentic Annotation Harness
Yihan Li, Hanyi Zhang, Xiaoxi Jiang et al. (+1 more)
Many annotation projects begin before experts have a stable guideline or enough labels to train a task-specific model. We present Goldsmith, an agentic pipeline that turns a small gold set—expert-annotated calibration examples representing the intended task boundaries—into a reusable structured annotation definition. Goldsmith treats this definition as a trainable textual object. Candidate definitions are run on the same gold examples and scored with an executable structured loss, while the output schema, formatting,
retrieval, repair, judging, and human review remain in an external harness. A large
language model (LLM) editor converts the highest-loss failures into textual-gradient revisions, which are accepted only when the measured loss decreases. In
prompt-optimization comparisons, Goldsmith improves over direct rewriting, OPRO, APE, and PromptBreeder under matched evaluation protocols. The resulting definition also improves downstream annotation when combined with
retrieval, score-based routing, and human review across typed span, pair-level relation, and fixed-trigger event-argument tasks. These results show that scarce expert supervision can support both task-definition learning and scalable annotation.
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All authors Yihan Li, Hanyi Zhang, Xiaoxi Jiang, Man Guo
Computation and Language · Cross-listed from eess.AS
Mitigating Accent-Language Confusion in Self-Supervised Speech Representations for Language Identification
Minu Kim, Jihwan Lee, David R. Mortensen et al. (+1 more)
Spoken
language identification (LID) aims to recognize the target
language regardless of accent. In practice, however, LID models fine-tuned from self-supervised
speech representations frequently confuse accents with
languages, misclassifying non-native (L2)
speech as the speaker's first
language (L1). We show that non-native
speech representations lie between native target-
language and native L1 poles, causing systematic misclassification. To address this, we introduce a
geometric projection that estimates an L1-bias direction solely from native
speech and removes it before the frozen LID head. Across five MMS-LID models and non-native corpora, this projection substantially improves target
language identification for L2-accented
speech while preserving predictions for native
speech. These results show that accent-induced L1 bias can be corrected directly within the representation space without L2 training data or model adaptation.
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All authors Minu Kim, Jihwan Lee, David R. Mortensen, Shrikanth Narayanan
Computation and Language · Cross-listed from cs.LG
CHASE: Channel-Aligned Structure Exploitation for Geometry-Aware Model Engineering
Wei Wang, Wei Jiang and Ziran Liu
Geometric and Spectral
Alignment (GSA) characterizes trained networks through spectral concentration, physical-channel
alignment, support structure, and changes in singular bases. In this paper, we propose CHASE (Channel-Aligned Structure Exploitation) to use these structures in practical model design. CHASE covers six applications across model modification, reconfiguration, and compression. CORA, COEC, and CORAM apply GSA to parameter-efficient finetuning, structured-
pruning compensation, and model merging. We further develop three new methods. CAGA uses GSA to identify multi-head
attention heads that can share a KV representation and constructs the shared key and value heads through
geometric alignment and low-rank subspace extraction. SAKV uses GSA to determine which adjacent layers can share a low-rank KV-cache representation and the retained rank for each layer group. CAPS uses GSA spectral structure to group output
neurons and selects retained input channels separately for each group. Results from CORA, COEC, and CORAM establish the effectiveness of GSA for adaptation,
pruning compensation, and model merging. Experiments on CAGA show that
geometric shared-head construction substantially improves MHA-to-GQA conversion, and SAKV and CAPS improve over representative baselines for KV-cache compression and structured
pruning. These results show that the structures identified by GSA can be used directly to design methods for a range of model operations.
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Computation and Language · Cross-listed from eess.AS
Boundary-Free Contextual Biasing: Depth-Adaptive Gating and Reading-Space Matching for Unsegmented Languages
Muhammad Huzaifah, Yu Pan, Zachary Yeo et al. (+2 more)
Contextual biasing supplies an ASR system with a list of expected words at inference time, but existing methods rely on word boundaries that Japanese and Chinese do not provide. We present a boundary-free biasing decoder for frozen public CTC models, built on a character-level Aho-Corasick automaton, with no training and no second pass. Two evidence-based mechanisms replace the boundary: a depth-adaptive gate that sets how hard to push from match depth, and reading-space matching for when the audio is right but the characters are wrong. On Aishell-1 NE's hard R1 subset we reach 66.5% recall, above the trained CLAS baseline (64%), transferring to WenetSpeech and to a second architecture without retuning. We release the first open Japanese contextual-biasing
benchmark, where biasing lifts rare-word recall by 25 points at precision above 97%, and still by 19 and 22 points against 1,000-word lists.
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All authors Muhammad Huzaifah, Yu Pan, Zachary Yeo, Ningjie Bai, Guangzhao Yang
Computation and Language
BanglaRhet: Benchmarking Classical and Transformer Models for Rhetorical and Persuasion Detection in Bangla Political Speech
Rohit Kumar Sen and Anik Chowdhury
Political discourse often uses rhetorical and persuasive
language to frame narratives, influence public opinion, and mobilize audiences. While Bangla natural
language processing has made progress in sentiment analysis and opinion mining, systematic benchmarking of
transformer models for fine-grained rhetorical and persuasion technique detection in Bangla political
speech remains largely underexplored. This paper presents a
benchmark study of
transformer-based models for detecting rhetorical form and persuasive intent in Bangla political discourse. Using BanglaRhet, a manually annotated corpus of 30,289 Bangla political
speech segments collected from publicly available political news sources, we formulate two supervised single-label classification tasks: rhetorical technique detection (contrast, repetition, exaggeration, metaphor, rhetorical questions) and persuasion technique detection (blame assignment, call to action, unity call, moral, emotional, and logical appeals). We evaluate four
transformer-based models, BanglaBERT, BanglaBERT-Base, SahajBERT, and XLM-RoBERTa-Base, against classical TF-IDF baselines. BanglaBERT achieves the highest performance, with 65.40% macro-F1 for rhetorical technique detection and 66.46% for persuasion technique detection, outperforming the best tuned classical baseline by 19.2 and 13.8 macro-F1 points, respectively. Class-level analysis indicates that errors are mainly associated with semantic overlap among labels, figurative
language, and class imbalance. The results provide initial
benchmark baselines for Bangla rhetorical and persuasion-aware political discourse analysis and highlight the need for context-aware and multi-label modeling.
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Computation and Language
Right Number, Wrong State? Measuring Cross-Jurisdiction Substitution in LLM Recall of State Policy
Jiayu Feng
When an LLM answers a state-specific policy question wrongly, it may be hallucinating, or it may be returning a real value that holds in another state. We test this with a minimal-set design: the question wording is fixed and only the jurisdiction varies, across the 50 U.S. states and the District of Columbia (51 jurisdictions) and three exactly defined Medicaid income-eligibility quantities. Gold values come from an official data book and agree with an independent source in 101 of 102 checked
cells. Under a pre-registered protocol, Claude Sonnet 5.5 and GPT-5.6 Sol reproducibly give another state's current value, identical across two independent repeats, for 10 and 25 of 153 items. The count depends on the reference set: crediting any wrong answer that equals another state's value yields 3-5x more reproducible substitutions than checking every number in the asked state's own records, because many apparent cross-state answers are the asked state's own values under another convention or from an earlier year. Claims about cross-jurisdiction error need a complete same-state reference set. We will release the protocol, gold table, and all model outputs.
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Computation and Language
Arctic Questions, Missing Answers: A Dataset and Benchmark for LLM Abstention in Arctic Science
Benjamin Wilcox, Dawei Gao, Pradeeban Kathiravelu et al. (+3 more)
Large
language models (LLMs) should abstain from scientific multiple-choice questions when no option is valid, but frequent abstention alone does not demonstrate sensitivity to answer availability. We introduce ArcticQA, a
dataset of 194 questions derived from primary Arctic research, with automated checks of answer support and distractor contradiction against source evidence. We further develop ArcticAbstain, a paired
benchmark comparing answer-present and answer-absent conditions, with the correct answer replaced by a distractor in the latter and an explicit abstention option in both. We evaluate eight models from the Gemini, Claude, and ChatGPT families at high
reasoning effort, with three trials per condition, yielding 9,312 recorded responses. Answer-present abstention rates range from 0.0% to 63.0%, whereas replacing the correct answer increases abstention by 5.05 percentage points on average. These findings highlight substantial baseline differences and the need to evaluate abstention frequency and responsiveness jointly. The
dataset and
benchmark are available at https://github.com/BenWilcox8/arctic-qa.
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All authors Benjamin Wilcox, Dawei Gao, Pradeeban Kathiravelu, Douglas Causey, Kewei Sha, Yunhe Feng
Computation and Language · Cross-listed from cs.IR
Finding the Right Balance: Relevance and Diversity in LLM Retrieval
Guillaume Brouillette, Faustin Kagabo, Usef Faghihi et al. (+1 more)
Retrieval diversification is widely available in
retrieval-augmented generation (RAG) frameworks, yet prior studies disagree on whether it improves
retrieval and answer quality. We show that its effectiveness varies primarily with candidate-pool redundancy, in a pattern consistent with the number of distinct evidence pieces a query requires. Using controlled near-duplicate injection and production-style overlapping chunking, we find that diversification harms relevance, evidence coverage and answer quality on clean pools, but becomes beneficial on multi-evidence tasks when redundancy causes nearest-neighbor
retrieval to select repeated passages. We therefore introduce a query-adaptive rule that diversifies only when the effective number of distinct documents in the nearest-neighbor top-$k$ selection falls below the query's evidence requirement. Computed from existing
embeddings, the rule captures most of the achievable gain, transfers across
datasets and encoders and automatically reduces to nearest-neighbor
retrieval for single-evidence queries. We also introduce RNG-Score, a
geometric reranker with an exact nearest-neighbor fallback whose margin indicates duplicate structure. Overall, we conclude that diversification should be used selectively, based on observable redundancy and evidence requirements.
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All authors Guillaume Brouillette, Faustin Kagabo, Usef Faghihi, Nadia Ghazzali
Computation and Language
ARCS: Towards Precise Text-to-SQL via Structured Disambiguation
Yihao Hu, Yanlin Feng, Naoki Otani et al. (+1 more)
As text-to-SQL systems move beyond demonstrations toward real-world deployment, ambiguity in user questions becomes a primary source of errors. Such ambiguities are often subtle, domain- or data-specific, and can silently cause system outputs to deviate from the user's true intent. Ambiguity is traditionally addressed through conversational clarification, which is often inefficient, cognitively demanding, and poorly aligned with real-world user workflows. We propose structured disambiguation, a new paradigm in which ambiguity is resolved through explicit, constrained interactions rather than free-form dialogue. We construct ARCS (Ambiguity Resolution Corpus for SQL), the first text-to-SQL
benchmark featuring naturally occurring, unconstrained ambiguities over real-world databases, with complete annotations of all valid ambiguity points, interpretations, and SQL queries. Experimental results show that text-to-SQL remains challenging in the presence of ambiguity: gpt-6-sol achieves only 51% end-to-end execution accuracy, and no open-source model exceeds 27%.
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All authors Yihao Hu, Yanlin Feng, Naoki Otani, Nikita Bhutani
Computation and Language
The Persona Hierarchy Model: Understanding Contextual Generalization in Fine-Tuning LLMs
Jiachen Zhao, Zhengxuan Wu, David Bau et al. (+1 more)
Language models are routinely fine-tuned under a fixed context, such as a generic system
prompt, persona or domain-specific instruction, yet the learned behavior sometimes stays confined to that context and sometimes broadly generalizes to unseen contexts. We propose the Persona Hierarchy Model to explain this: a shared default persona influences behavior across contexts. Under this model, fine-tuning that modifies the shared persona promotes broader transfer, whereas changes to local personas remain more context-specific. Across 120 fine-tuned models spanning four behaviors and 15 training contexts, generalization narrowness positively correlates with the similarity between the training context's persona and the default persona (Pearson's r = 0.72 for Qwen3-4B). Prior fine-tuning under the default context can broaden generalization in subsequent training under other contexts. Aligning contextual responses with default-persona responses produces stronger effects. Finally, we propose persona-preserving regularization (PPR) to confine undesired contextual generalization. In RL, PPR cuts reward hacking from 42-55% to at most 0.2% under every evaluated
prompt while retaining accuracy gains. These results support the Persona Hierarchy Model as an explanation for contextual generalization and can motivate future controls on unintended generalization for better
alignment of LLMs.
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All authors Jiachen Zhao, Zhengxuan Wu, David Bau, Weiyan Shi
Computation and Language
Expert Coupling in MoE Pretraining: Reducing All-to-All Overhead with Correlated Placement and Token Shuffling
Radha Gulhane, Quentin Anthony and Beren Millidge
Mixture-of-Experts (MoE) layers replace the feed-forward block of a
Transformer with E expert networks, and each
token is routed to k of these experts. Under expert parallelism (EP) the experts are distributed across GPUs, and every MoE layer runs all-to-all collectives in the forward and backward passes to dispatch
tokens to their experts and then combine the results. On a cluster with 8 AMD Instinct MI300X GPUs per node, these collectives can take 45% of the training step at EP32 with top-2 routing and 60% with top-6 routing. We find that early in pretraining routers have already learned to assign
tokens to experts in correlated patterns, both within a layer and across layers. At top-2, 0.8% of the expert pairs in a layer are selected together by 42% of
tokens, and the experts a
token selects at one layer predict the experts it selects at the next layer. We use these correlations to keep more
token–expert assignments on the
token's own GPU, which reduces communication across GPUs and across nodes. Correlated expert placement puts experts that are often selected together on the same GPU. Combined with a dispatcher that sends each
token to each GPU once, it removes up to 58% of dispatched rows.
Token shuffling applies when sequence parallelism shards
tokens across the EP group. It moves each
token to the GPU predicted to hold its next-layer experts during the reduce-scatter that follows
attention. On one node this raises the share of
token–expert assignments served on the
token's GPU from 12.5% to 59%. In Megatron-LM, across EP degrees from 8 to 64 with top-2 and top-6 routing, the two methods reduce all-to-all time by 1.16-2.63X and end-to-end step time by up to 1.41X. Neither method changes the models' underlying routing decisions or expert parameters.
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Computation and Language · Cross-listed from cs.GT
The Confidence Game: Strategic Miscalibration in Human-AI Delegation
Raghu Arghal, Saswati Sarkar and Shirin Saeedi Bidokhti
Calibrated uncertainty quantification is essential to ensuring AI
agents are trustworthy and reliable. However, when
agents seek to maximize user engagement or revenue, confidence reports may be strategically distorted, detracting from their informativeness. We formalize this problem in the Confidence Game: a repeated signaling game with imperfect monitoring in which an
agent of unknown honesty and ability reports its confidence, and a user decides whether to delegate the task or complete it herself. The
agent manages the tradeoff between manipulating signals and maintaining its reputation. We characterize the Markov Perfect
Bayesian Equilibria of the two-period game and show that honest reporting is not an
equilibrium, inflation is the unique best response once the
agent is sufficiently myopic, and under-reporting requires that the user believe honesty to be a minority. We then place an LLM in the
agent role, supplying it with its true probability of success so that any gap between what it knows and what it reports is attributable to incentives rather than to miscalibration. The model claims high confidence on 56% of tasks it has been told it will probably fail. This persists on real tasks, where it must estimate its own accuracy and causes miscalibration to increase while the
agent's signal becomes less informative. Furthermore, we find that the LLM
agent's decisions are coherent, but it systematically underestimates both how likely the user is to delegate and how secure its reputation is, resulting in less extreme behavior. Pricing the
agent's reporting rule, we find that it destroys 68% of the gains from delegation, of which 71% is information the report no longer carries and no amount of user sophistication recovers. Overall, we establish confidence reporting under delegation as a strategic problem and provide a tractable basis for modeling, analyzing, and testing
agent behavior.
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Computation and Language · Cross-listed from cs.AI
TopoGraphRAG-Bench: Evaluating Multimodal GraphRAG on Layout-Grounded Evidence Reasoning
Ruochi Li, Jianzhe Lin, Haoxuan Zhang et al. (+4 more)
Real-world documents distribute evidence across text, tables, figures, and captions within complex page layouts. Answering complex questions over such documents therefore requires more than retrieving relevant passages: systems must recover the evidence
topology that connects heterogeneous evidence units. Existing GraphRAG evaluations remain largely text-centered, while
multimodal document RAG
benchmarks assess cross-modal
retrieval and generation without directly evaluating recovery of the intended evidence
topology. We introduce TOPOGRAPHRAG-BENCH, a layout-grounded
benchmark for
multimodal evidence
reasoning in GraphRAG, comprising 2,024 questions over 201 long, visually rich documents. Questions are constructed bottom-up from text, figure, and table evidence units under three controlled
topologies: single-hop
retrieval, bridge-chain
reasoning, and multi-source synthesis. To ensure that questions preserve their intended structure, we apply counterfactual validation for shortcut resistance, modality necessity, and evidence necessity. We evaluate text-only GraphRAG, page-level visual
retrieval, and
multimodal GraphRAG systems using
retrieval, generation, and
topology-aware
reasoning metrics.
Multimodal GraphRAG systems achieve the strongest overall performance, but still fail when visual-textual evidence
alignment or multi-unit composition is incomplete. Text-only GraphRAG struggles when key dependencies are grounded in figures or tables, while page-level visual
retrieval lacks the fine-grained structure needed for
topology recovery. These findings motivate GraphRAG systems that move beyond text-derived entity relation graphs to explicitly model document layouts, cross-modal evidence
alignment, and the
reasoning roles of evidence units. Code and data are available at https://richardlrc.github.io/TopoGraphRAG-Bench/.
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All authors Ruochi Li, Jianzhe Lin, Haoxuan Zhang, Haihua Chen, Junhua Ding, Edward Gehringer, Yang Zhang
Computation and Language
OnlineQAT: On-Policy Distillation for Ultra-Low-Bit Large Language Models
Wenjun Wang, Heng Li, Yanggan Gu et al. (+1 more)
Quantization-aware training (QAT) can recover much of the accuracy lost when large
language models are compressed below four bits. Existing re- covery stages, however, are commonly optimized on fixed completions or teacher-generated answers, whereas the deployed quantized model condi- tions on prefixes generated by itself. Quantization errors can therefore move the model into states that are absent from offline recovery data. We introduce OnlineQAT, a two-stage framework that first obtains a usable low-bit initialization through block-wise QAT and then performs on-policy
distillation (OPD) on student-generated responses. At each visited pre- fix, a frozen full-precision teacher provides a sampled reverse-KL training signal. On Qwen3-1.7B, OnlineQAT obtains the best average among the compared quantized methods: 57.28 at W3A16 and 32.52 at W2A16, im- proving over ReasoningQAT by 2.90 and 0.44 points, respectively. The results suggest that student-visited states provide a useful recovery signal beyond fixed-completion training, particularly at three bits.
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All authors Wenjun Wang, Heng Li, Yanggan Gu, Hongxia Yang
Computation and Language
Dialect-Robust Speech Language Models with Synthetic Pseudo-Dialect Augmentation
Shunsuke Mitsumori, Tomoya Mizumoto and Yusuke Fujita
Speech Language Model (SLM) performance often degrades on dialects due to data scarcity. Conventional text-to-
speech (TTS) augmentation struggles to cover diverse dialects as it requires a certain amount of real dialect
speech. We propose synthesizing pseudo-dialect
speech by converting LLM-generated dialect text via a standard-
language TTS model, requiring zero real dialect
speech. Additionally, we introduce intermediate standard-text prediction during training, acting as semantic normalization for downstream tasks. We evaluate dialect understanding via dialect-to-English
speech translation across Japanese, German, and Chinese dialects. Compared to synthetic standard
speech baselines, pseudo-dialect augmentation improves scores for Japanese (from 25.38 to 26.24) and German (from 31.57 to 32.47). Furthermore, the intermediate standard-text prediction effectively bridges the semantic gap, boosting performance to 28.26 for Japanese and from 11.67 to 16.37 for Chinese. These results suggest that our approach scales to various
languages without requiring
speech resources specific to each dialect.
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Computation and Language · Cross-listed from cs.CR
Adversarial Images Hijack Web Agents from Visual Grounding to Browser Execution
Wanjing Han, Levi Taiji Li, Mu Zhang et al. (+2 more)
Modern web
agents built on large
vision-
language models process webpages, select relevant UI elements, and translate model outputs into browser actions. Existing visual red-teaming approaches use
adversarial visual content to manipulate this process. However, they primarily target model inference and do not explicitly account for structured input processing or action post-processing. Consequently, model-level success does not establish control over browser execution and cannot reliably characterize end-to-end
agent robustness. To address this gap, we formulate red teaming for
vision-grounded web
agents as an end-to-end grounding-to-execution problem, and introduce WebMirage, a framework that crafts localized visual perturbations that cause
agents to select attacker-controlled content and execute the corresponding browser action across varying webpage renderings. It uses a role-slot abstraction and webpage recomposition to capture competition among webpage elements, and dataflow analysis to align optimization with action post-processing. We evaluate WebMirage across four
agent configurations and six VLM backbones on 2,250 tasks covering 13 public websites and a sandbox
benchmark. WebMirage achieves an average attack success rate of 91.9%, compared with 17.4% for the strongest baseline, and remains effective against three
agent-level defenses.
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All authors Wanjing Han, Levi Taiji Li, Mu Zhang, Yue Jiang, Guanhong Tao