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cs.AIcs.CL Simiao Ren, Xingyu Shen, Tommy Duong et al. · Oct 22, 2026

The paper tests whether small wording changes can shift AI models from refusing to complying with a sensitive request: increasing income on a pay stub. Across 15 models and 445 simulated trials, the authors compare three prompt framings—stating a loan purpose, omitting the reason, or describing a printing error—and find that editing-call rates rise sharply from 14.1% to 66.2%. The work matters because it offers a concrete, traceable probe of boundary robustness in financial-document scenarios, though the authors are careful to say it does not establish an ethics ranking or prove real-world harm.

Can a small change in wording move an AI model from refusing a sensitive request to acting on it? We test 15 models on the same request to increase the income shown on a pay stub. Across 445 observable trials, models issue editing calls in 14.1% of cases when a loan purpose is stated, 33.1% when the purpose is omitted, and 66.2% when the change is described as fixing a printing error. Astra refuses all ten loan-purpose requests but issues calls in all ten purpose-omitted trials. Fable, Opus, and Muse Spark issue none across all three wordings; Sonnet issues some under the latter two. Response excerpts illustrate different ways of refusing, redirecting, or justifying an edit. The file is a marked test document and all tools are simulated. These results probe how boundaries behave in one setting; they do not prove an overall ethics ranking or that a harmful real-world edit succeeded.
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cs.CLcs.AIcs.CY Chenhan Lyu, Kit Wislocki, Sarah Elizabeth Stoeckl et al. · Oct 22, 2026

Mental-health chatbots powered by LLMs risk unsafe outputs, yet current safety layers are opaque and developer-driven. This paper proposes a clinician-led guardrail in which two doctoral trainees in clinical psychology author four safety checks, which are then formalized over sixteen typed facts and verified for internal consistency with an SMT solver before deterministic execution. The core claim is not superiority in accuracy but in inspectability: every verdict recomputes from named rules and facts, making disagreements localizable and revisable.

Large language models (LLMs) deployed in mental-health contexts can be evaluated for safety failures, but the resulting judgments are often difficult to inspect or explain. Common approaches to improving safety rely on prompt engineering, LLM-as-a-Judge, and Constitutional AI. In this work, we describe a clinician-led alternative in which two clinicians define, finalize, and adjudicate the four safety checks of a rule base, which is formally verified for internal consistency and applied as a guardrail over LLM outputs. Here and in the title, clinician-led refers to this rule base, not to the fact extractor or the uncertainty default, which are ours. Every verdict of the resulting verification layer is recomputable from a named rule and sixteen facts. Against an LLM judge matched in model, revision, quantization, rule text, and decoding but without the layer's computed 988/911 fact, the largest disagreement class, the satisfied-rule class, is structured: the Llama-3.3-70B judge, on its primary prompt, demands a crisis resource from 55 of the 65 replies (84.6%) that already contain one, while the same model, asked as a fact extractor, reports a recognized resource present on 54 of the 55. The verification layer never raises that demand, by construction. We report with equal prominence where this judge is stronger: fewer false crisis alarms on the one reference-scored check. We also report the measured cost (a specification revision raised block-class outcomes on held-out boundary prompts of an over-refusal benchmark from 6.0% to 16.0%, chiefly by changing fact extraction), the clinicians' decision to keep our uncertainty default, and the analysis of the result. The contribution is not a safer verdict. It is a guardrail whose disagreements with the judge localize to named rules and facts and whose measured costs trace to named facts and the uncertainty default.
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cs.CLcs.AI Yang Liu, Zhiqiang Yuan, Shu-Dong Huang et al. · Oct 22, 2026

ULME tackles the frictions between text embedding and text generation, which are usually handled by separate models with incompatible objectives. The paper proposes a post-training framework for causal decoder-only LLMs that inserts a chain of learnable slots between the query and answer, then couples the two tasks via a stop-gradient predictive loss so that generation actively shapes the embedding. Across eight scales of Qwen2.5 and Qwen3 (0.5B–8B), a single ULME checkpoint raises MTEB scores by 3.3–4.1 points over the strongest open baseline while remaining on par with generation-only fine-tuning on standard accuracy benchmarks.

Text embedding and text generation are two of the most useful capabilities of modern large language models, yet they are typically provided by separate specialized models (an embedder and a generator) trained with incompatible objectives and deployed side by side in retrieval-augmented generation and agent systems. Recent unified embedding-generation models such as GritLM share parameters between the two capabilities, but they either switch attention regimes between modes or optimize embedding and language modeling as parallel objectives that never supervise each other. We argue that these designs are only partially unified: the two capabilities coexist on the same weights, but do not shape each other. We propose ULME, a post-training framework that unifies embedding and language modeling on a causal decoder-only LLM through predictive coupling. ULME inserts a chain of learnable slots between the query and the answer, reads a semantic embedding and a reasoning embedding from two designated slots, and trains three objectives on a shared causal backbone: a contrastive loss anchoring the semantic slot to document representations, a language-modeling loss supervising answer generation, and a stop-gradient predictive loss that aligns the reasoning slot with a pooled summary of the answer, so that generation actively shapes what the embedding encodes. Across two model families (Qwen2.5, Qwen3) and eight scales spanning 0.5B-8B parameters, a single ULME checkpoint improves MTEB by 3.3-4.1 points over the strongest open-source baseline, tightens BRIGHT and AdvBench-IR simultaneously, and remains on par with a generation-only fine-tune on standard accuracy benchmarks (MMLU, GSM8K, MMLU-Pro, HumanEval), demonstrating that genuine unification yields mutually reinforcing rather than merely coexisting capabilities.
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cs.AIcs.CLcs.CR Yuchen Wu (University of Washington), Jerry Wei (Anthropic) · Oct 22, 2026

The paper asks how to predict the performance of a safety probe before it is trained. Its core finding is that probe error follows two scaling laws: a power-law floor in model size and a Hill-curve approach to that floor as labels increase. This matters because it could let safety teams budget labels and choose architectures for new models without expensive grid search.

Safety probes trained on a model's activations are a standard tool for monitoring language models in real time. Each time a new model is released or a new harm area needs to be monitored, the probe must be retrained, which requires new labels and a choice of probe architecture. Yet neither the model nor the labels tell us in advance how well the resulting probe will perform. Finding out requires training and comparing many probe configurations. In this paper, we ask whether probe performance can instead be predicted in advance from model size and the number of labels. Existing safety datasets are insufficient for this, as they are either limited in scale or already saturated. We therefore construct six new safety datasets of sufficient size and difficulty. On these datasets, we train two probe architectures on 20 base models from five model families, with 32 to $10^{6}$ labels for each model. We measure performance using probe error, defined as 1 - AUROC, where lower values are better. We find that probe error follows two simple scaling laws. First, the lowest probe error a model can reach falls as a power law in its size. Second, probe error decreases towards its floor as the number of examples increases; the slope increases as the target model size increases. Both laws hold across tasks, model families and probe architectures, and only their fitted constants differ. When fitted on the smallest models of a family, the laws predict the error of the next larger model to within 0.02 in 72% of cases. They also identify whether more labels or a larger model is the cheaper way to reach a target error in 73% of cases. Finally, they choose the probe architecture with an extra error of only 0.006 on average when they pick the worse one. These laws allow safety researchers to determine how to create the best probe for any given model and label budget.
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cs.CLcs.AI Qince Luan, Jianhui Xu, Yang Xu · Oct 22, 2026

Singular-value spectra shape how transformer MLPs amplify different directions, yet their causal role in downstream capabilities is poorly understood. This paper introduces a post-hoc "Matthew" perturbation that reweights the singular values of MLP up_proj and down_proj matrices around their geometric mean—spiking inequality with $\alpha>0$ or smoothing it with $\alpha<0$—while preserving singular vectors and the geometric mean. Across five instruction-tuned Llama and Qwen models, the authors evaluate perturbed systems on 118 capability-labeled subtasks, auxiliary benchmarks, and personality probes, arguing that spectral inequality is a manipulable variable that can selectively trade off factual knowledge, language understanding, and deductive reasoning without retraining.

Singular-value spectra encode important structure in transformer feed-forward projections, yet their causal role in downstream behavior remains underexplored. We study post-hoc spectral smoothing and spiking interventions on the up_proj and down_proj matrices. Positive perturbation stretches deviations from the geometric mean, making large singular values larger and small ones smaller (spiking), and vice versa. The intervention preserves singular vectors and the geometric mean of the singular values. Across five open Llama and Qwen instruction models, we evaluate the perturbed systems on capability-labeled subtasks, standard and chain-of-thought reasoning benchmarks, judge-scored truthfulness, hallucination, and safety tasks, and TRAIT personality probes. To interpret score shifts, we fit responses in a three-dimensional capability basis consisting of factual knowledge, language understanding, and deductive reasoning. The induced changes suggest structured rather than purely random sensitivity: large positive perturbations more reliably suppress language and deductive responses, moderate negative perturbations can sometimes improve factual or task-local performance on the evaluated grids, and sensitivity varies strongly by model family, benchmark module, and underlying layerwise spectral inequality. These results position spectral perturbation as a lightweight intervention for probing how capabilities are organized and traded off in large language models.
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cs.AIcs.CL Rhitabrat Pokharel, Ameeta Agrawal · Oct 22, 2026

When a multilingual LLM flips its answer under user pressure, it is unclear whether it knew the correct answer and yielded (sycophancy) or simply lacked competence in that language. This paper introduces the SC-matrix, a $2 \times 2$ diagnostic crossing Competence ($C$) and Sycophancy ($S$) to decompose behavior into four cells: Robust, True Sycophancy, Honest Uncertainty, and Uninformed Deference. Their experiments across six languages and three models show that aggregate sycophancy rates hide very different failure mixtures, and that reasoning-based prompts outperform direct alignment instructions at reducing pressure-induced flips.

When a multilingual LLM agrees with a user's false premise, is it being sycophantic, or does it simply not know better in that language? Current research does not distinguish these cases: they record only whether the model agreed, not why. We introduce the SC-matrix, that crosses a model's competence (whether it answers correctly under no pressure) with its sycophancy (whether it maintains that answer under pressure). Our results show that (1) identical aggregate sycophancy rates can mask different failure compositions, (2) high competence in a language does not always protect against sycophancy, and (3) reasoning-oriented mitigations outperform directive-based strategies. We find that multilingual sycophancy is not a single phenomenon but a composite of different failures that require distinct diagnosis.
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cs.AIcs.CL Tim Wenjie Hu, Evelyn Nafula Ouma, Benjamin Akera et al. · Oct 22, 2026

This paper investigates whether Group Relative Policy Optimisation (GRPO), previously applied to LLM-based speech recognition, can improve smaller encoder-decoder ASR models in a multilingual, low-resource setting. Using Whisper-large-v3 as a case study, the authors train SunflowerASR on 51 African languages and report state-of-the-art macro-averaged WER on AfriVox-v2 and SimbaBench. Key innovations include a headroom-based training example selection strategy and careful ablations isolating the reinforcement signal from mere additional training.

Autoregressive encoder-decoder speech recognition models trained with teacher forcing can suffer from exposure bias, limiting their ability to recover from their own prediction errors at inference time. Recent work has shown that reinforcement learning with Group Relative Policy Optimisation (GRPO) improves speech recognition in major languages with LLM-based models. We extend this line of work to smaller, non-LLM encoder-decoder ASR models, using Whisper-large-v3 as a case study across 51 African languages. The benefits of this approach are most pronounced when training data is scarce or when input audio is noisy or degraded. Our resulting model, SunflowerASR, achieves the best published macro-averaged WER on the AfriVox-v2 (0.227) and SimbaBench (0.372) benchmarks, and is publicly available.
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cs.AIcs.CLcs.MA Yebo Feng, Jingyang Dai, Liangrui Pan et al. · Oct 22, 2026

Steward is a multi-agent LLM trading system designed to act on live Web data while keeping its safety constraints intact as it learns. The paper introduces governed self-evolution: a deterministic gate and typed proposal system let the agent rewrite its own prompts, but an invariant core of risk rules, order arithmetic, and discipline-agent prompts is unreachable by any self-edit. In a five-month live paper-trading deployment the authors record every input, output, and grading event to evaluate whether the architecture survives real market noise, prompt injection, and its own reflection loop. The release of the full code, prompts, and replay harness makes this one of the most transparent live-agent studies to date.

LLM agents that act on live Web data must combine heterogeneous evidence, remember what they have done and improve from outcomes without weakening their own safeguards. We study this problem in autonomous investing, where every action is irreversible and based on untrusted Web content. We present Steward, a multi-agent LLM system that draws the boundary of self-evolution in its type system. First, nine role-specialised agents decide jointly: four analysts read news feeds, SEC filings, macroeconomic series and market data and emit typed reports, from which a Portfolio Manager sets target positions that a protected Risk Manager audits. Second, a seven-layer shared memory, assembled by code from the system's own record, gives each decision its position context, the market narrative, calibration and the agent's past decisions. Third, the system improves itself by review: code grades every trade and forecast nightly and writes the grades into memory, and each quarter a reflector proposes prompt learnings that a deterministic gate applies reversibly and replay of recorded inputs verifies. All three operate around an invariant core of order arithmetic, risk rules and discipline-agent prompts that no self-edit can reach. In a five-month live deployment (102 trading days, 1,632 LLM calls), the system contained a 24.6% sector drawdown to a 0.3% loss; in replay of its recorded inputs, a single model given the same raw data traded more and lost 1.35 points against the market over five days where the joint design showed no significant loss, and no injected instruction was followed; and a 2015-2026 backtest shows the core alone lowering the maximum drawdown under all 50 random entry policies. The reflector traced the dominant failure to its root cause, and the gate applied a learning that the agent adopted on trigger evenings and on no control evening. Code: https://github.com/yebof/quant-agent
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cs.CLcs.CYcs.LG Zhangqi Duan, Simon Woodhead, Maya Miller-Vedam et al. · Oct 14, 2026

Traditional student models only use responses to standalone questions, ignoring the rich, fine-grained evidence embedded in tutoring dialogues. This paper proposes URF-QD, a framework that rewrites tutor-posed mathematical subtasks as self-contained questions and models them jointly with original items on a shared item response theory scale. The key novelty is a relative-order regularization that uses tutor pedagogical moves to constrain consecutive subtask difficulties, enabling dynamic tracking of student ability across both questions and dialogues. The authors show consistent improvements on two real-world math datasets, though the approach leans heavily on LLM annotations and modest sample sizes.

Existing student models in educational applications largely focus on student responses to questions. However, as tutoring becomes more accessible at large scale, it is important to analyze dialogues between tutors and students, which may reveal fine-grained evidence on student knowledge. In this work, we propose a unified framework that models both student responses to questions and tutor-posed subtasks during dialogues on a shared item response theory (IRT) scale. We first identify mathematical subtasks in tutoring dialogues, rewrite them into self-contained questions, and identify the correctness of student responses to these subtasks. We then develop an IRT framework that estimates question/subtask difficulty from text, tracks students' evolving abilities across question-answering and dialogue interactions, and a novel method to leverages tutor moves between consecutive subtasks to regularize their difficulty values. We evaluate our framework on two real-world math education datasets containing both human- and AI-tutored dialogues. Results show that our framework outperforms strong baselines on both question difficulty prediction and response correctness prediction.
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cs.CLcs.LG Shuxuan Li, Jialiang Kang, Yanghao Zhou et al. · Oct 14, 2026

Speculative decoding drafters trained on short sequences collapse on long-context inputs because their position encodings extrapolate poorly. FOLD fixes this without retraining by keeping exact positions in a local window and compressing all distant context into a shared-position far memory. A concentration factor $\alpha$ in a decoupled softmax prevents attention dilution as the memory grows. Across six target–drafter pairs and contexts up to 256K tokens, the method consistently raises speedup, in the best case more than doubling it.

Speculative decoding accelerates LLM generation through lightweight drafting and parallel verification. It is particularly promising for long inputs, where KV-cache access costs can be amortized over multiple accepted tokens. Yet most drafters are trained on short sequences and degrade on long inputs, while long-context training is costly. Existing training-free approaches restrict the context window, rescale positions, or augment recent context with retrieved distant entries. Drafters, however, read target hidden states that already encode contextual and positional information, and their lightweight architecture makes full-history attention affordable. We propose FOLD, a training-free method that preserves exact local positions and treats all distant entries as far memory at a shared position. To counter attention dilution as the memory grows, we sharpen attention within it to emphasize relevant entries while separately controlling its total weight relative to the local window. Across six target-drafter pairs and diverse benchmarks of up to 256K tokens, FOLD predominantly delivers the highest speedup, with the best case more than doubling the speedup over autoregressive decoding, from 2.08$\times$ to 4.22$\times$.
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cs.CLcs.LG Ian Magnusson, Noah A. Smith, Pang Wei Koh · Oct 14, 2026

COUNT tackles the GPU-memory bottleneck of scaling language-model embeddings by replacing learned n-gram tables with precomputed corpus counts stored on cheap host RAM. It constructs input embeddings via a weighted sum of the model's own unembedding vectors, requiring no extra learned parameters and enabling training-free domain adaptation at inference. On 60M--1B-parameter backbones, the authors demonstrate consistent perplexity and downstream gains without increasing GPU memory pressure.

The scaling relationship of compute and performance for language models (LMs) has been extensively studied; more recently, models are being designed to scale memory use, as well. In particular, adding embeddings for n-grams scales memory separately from compute use, because each pass only processes individual embedding rows, which are much smaller than the storage used for the whole embedding table. However, existing methods train embeddings from scratch, which needs expensive GPU memory for fast reading and writing. Meanwhile, the ordinary memory of the host system is cheap and underutilized by these training methods. To scale on host memory, we introduce COUNT (Counting Offline Unlocks N-gram Transformers), which builds n-gram embeddings without adding learned parameters by storing precomputed n-gram counts on host. We use the corpus frequencies to weight together the LM's own unembeddings of the next tokens most often following the current n-gram history. At a fixed compute budget, COUNT can be added as an additional input embedding for pretraining 1B-parameter LMs to improve validation loss as much as an LM with 57% more compute. If GPU memory is limited, using COUNT to let backbone parameters fill GPU memory gives better performance than splitting memory with additional learned n-gram embeddings. Beyond efficiency, COUNT allows switching in a different table of n-gram counts from a domain-specific corpus at inference time to adapt to a new task without any training.
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cs.LGcs.CL Minsuh Joo, Youna Kim, Choonghyun Park et al. · Oct 14, 2026

Current evaluations of Knowledge Extraction Enhancement (KEE) techniques collapse recovery and disruption into a single accuracy score, concealing critical trade-offs. MAPLE introduces a unified diagnostic framework built on a pretraining-verified benchmark and three complementary metrics—surface-level $\text{Gain}/\text{Loss}$, probability-level $\text{PRS}$, and beyond-sampling $\text{SGR}/\text{DGR}$—to dissect intervention effects at multiple levels. Across six techniques and three model families, MAPLE shows that prompting recovers deep failures but disrupts many successes, while decoding and steering often reshuffle token probabilities without consistent benefit. The work offers a principled, actionable standard for comparing KEE methods beyond headline accuracy.

LLMs absorb vast knowledge from training data, yet their inherently probabilistic nature offers no guarantee that this knowledge will surface in their outputs. To bridge this gap, Knowledge Extraction Enhancement (KEE) techniques such as activation steering, decoding adjustments, and prompting modify inference, potentially reinforcing existing predictions or surfacing less accessible answers. Yet their evaluations centered on aggregate accuracy, which obscures diverse effects by collapsing recovered failures and disrupted successes into a single score. We introduce MAPLE, a unified framework for characterizing how KEE techniques affect parametric knowledge extraction. Its diagnostic metrics disentangle these effects at the surface, probability, and beyond-sampling levels by measuring answer recovery and disruption, gold-token rank shifts on unrecovered failures, and recovery of answers missed by fixed-budget sampling. We evaluate six KEE techniques spanning decoding, activation steering, and prompting across three model families: OLMo2, Qwen2.5, and Llama3. Our analysis reveals distinct effects and trade-offs across techniques, highlighting the value of MAPLE for understanding and comparing KEE beyond aggregate accuracy.
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cs.CLcs.LG Junyi Zou, Avrova Donz · Oct 14, 2026

MMLA-RSI proposes recursive self-improvement through two Memory-Mediated Learning Architecture routes: Reasoning-Time Training (RTT) treats the numerical policy-state updater as an object of improvement, while Reasoning-Time Memory Adaptation (RTMA) treats the memory-management rule as an object of improvement. Each admitted successor takes over its parent's role in producing the next generation's rule. The paper's main contribution is a formally bounded construction with shared interfaces and a common algorithm, though the authors explicitly state that beneficial recursive chains remain to be evaluated.

An agent can improve its behavior within an unresolved problem by changing how it acts and which experience it retains. We propose MMLA-RSI, a recursive self-improvement scheme with two implementations in Memory-Mediated Learning Architecture: Reasoning-Time Training (RTT) changes the policy state $\Phi$, while Reasoning-Time Memory Adaptation (RTMA) changes authoritative memory $M$. Each route also makes its adaptation method an object of improvement. A current numerical updater trains the policy proposing its successor; a current memory manager chooses the records available to the process proposing its successor. An independently admitted successor takes over the same role in the next generation. We give bounded executable rule languages, shared task/proposal interfaces, and one algorithm for either route or their composition. The RTT instance changes scalar schedules in a clipped-momentum update. The RTMA instance chooses NULL or a complete-row write with possible eviction. A fixed interpreter, trusted committer, and independent evaluator bound what can change. State versions, read closures, and conditional properties describe causal execution, accepted transitions, and finite work. Existing numerical-component studies motivate the construction. In four-candidate program selection, retaining LARC feedback updates reduces expected error by 24.65 and 36.65 percentage points for two trained initializations. In chronological continuous-integration replay, feedback binding is positive while retention increases loss. Completed SQL studies improve substantially over an unadapted substrate but do not establish the required additional online benefit. These results characterize their declared components. The two recursive routes and their joint realization are specified here; their beneficial recursive chains and discovery efficiency remain to be evaluated.
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cs.CLcs.LG Linhao Zhong, Bozhen Fang, Xuehao Wang et al. · Oct 14, 2026

This paper confronts the evaluation crisis in agentic self-distillation, where a flood of recent methods claim gains over GRPO using inconsistent protocols and reused baselines. The authors conduct a unified benchmark of ten representative approaches across four tasks, three model sizes, and 132 training runs totaling over 12,000 H800 GPU-hours, measuring not only final accuracy but also training stability and wall-clock cost. Their central finding is sobering: no method consistently beats GRPO, many suffer severe hidden instability, and extra compute rarely translates into better agents.

Self-distillation in agentic reinforcement learning has produced a growing number of methods. However, existing evaluations often reuse published baseline scores under differing experimental conditions, provide few direct comparisons among contemporaneous methods, and give limited attention to training stability and computational cost. These limitations obscure the source of reported gains and the practical strengths and weaknesses of competing methods. Costly agent training further motivates a common basis for comparison. To address these gaps, we compare ten representative methods against GRPO on ALFWorld, ScienceWorld, Search-QA, and WebShop across three model sizes. Our study comprises 132 training runs totaling 12,124.4 recorded H800 GPU-hours, with repeated evaluations over eight rollout seeds for the pretrained backbones and all eleven trained methods. Beyond final task performance, we examine training progress, stability, and measured computational cost. Our evaluation yields three key findings. First, gains over GRPO remain limited in scope, with no method consistently outperforming it across settings. Second, strong final performance can mask unstable training. Third, additional training cost does not consistently translate into better performance. We establish this benchmark to support fair, comprehensive comparison and guide future research toward reliable and cost-effective improvements in agent training. Project page: https://aim-uofa.github.io/Self-Distillation-AgentRL/
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cs.LGcs.CL Yuxuan Wang, Guangxiang Zhao, Xinyu Tan et al. · Oct 14, 2026

Supervised fine-tuning can collapse the pretrained model's preference structure among non-target tokens. Instead of matching the reference distribution exactly like LP-SFT, this paper proposes SRP-SFT, which enforces soft, selective lower bounds on margins between top-K non-target token pairs. At one epoch on a 4B model, it improves MATH-500 pass@1 from 49.56 to 54.56 over LP-SFT, with consistent gains across three seeds.

Supervised fine-tuning (SFT) changes logit margins among non-target tokens at teacher-forced prefixes. Matching a local reference distribution keeps those probabilities and also penalizes margin expansions. We ask whether a soft auxiliary can preserve selected local non-target margin relations without freezing that distribution. We introduce \textbf{Selective Rank-Preserving SFT (SRP-SFT)}, a soft margin target: a hinge on reference-scaled lower bounds for pairs from the reference's top-$K$ non-target tokens, applied at fixed teacher-forced prefixes. The hinge stops once the requested bound is met. We derive the KL cost of violating a margin, characterize the feasible region and its conditional utility, and give a finite-step condition for reducing aggregate violations. In one-epoch experiments on Qwen3-4B-Base and UltraFeedback, this target raises MATH-500 and code-generation scores over CE and LP-SFT at all three training seeds. At seed 1234, MATH-500 pass@1 rises from 49.56\% to 54.56\% and the four-metric code mean rises from 65.91\% to 69.50\% relative to LP-SFT. Ranking controls, held-out cache diagnostics, sensitivity sweeps, and six additional backbones show where these score changes appear.
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cs.LGcs.CL Minchan Kim, Sungho Bae, Youngjin Kim et al. · Oct 14, 2026

GRPO for long-horizon agents suffers from sparse terminal rewards that yield all-fail rollout groups and zero advantage signals early in training. This paper studies guide-assisted curricula that replay successful reference prefixes before the learner continues, systematically varying the initial position, handoff granularity, and movement rule. Across Qwen3 models from 1.7B to 8B on BFCL and AppWorld, the authors find that starting near task completion and using outcome-informed call-level selection improves independent execution while reducing training cost. The work usefully frames curriculum design as a practical lever for GRPO-based agent post-training.

Group Relative Policy Optimization (GRPO) provides no reward-relative learning signal when all rollouts receive identical rewards. In long-horizon tasks that require multiple interactions, rewards are given only upon successful task completion, making all-fail groups common early in training and limiting opportunities to practice later steps. Guide Assisted GRPO replays a successful reference prefix before the learner continues. We study how initial positions, handoff units, and movement rules affect unassisted task completion. Across three model sizes on BFCL, starting near completion is more effective under a fixed turn-level threshold rule. Finer handoffs alone do not consistently help, but outcome-informed tool-call selection outperforms GRPO on trained and untrained task categories. Guided starts also improve AppWorld success on both evaluation splits. These findings highlight where learning starts and how starting positions move as key curriculum choices.
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cs.LGcs.CL Qinglin Su, Licheng Pan, Zhen Fang et al. · Oct 14, 2026

RM-OPD targets a real bottleneck in generalist reward modeling: training on mixed-domain data with standard RL produces cross-domain interference and sparse outcome rewards, so capabilities like math verification, code review, and safety guardrails cannot coexist without degrading each other. The core idea is a two-stage framework—first cultivate domain-specialist reward teachers via single-domain GRPO, then distill them into one student through routed on-policy distillation, domain contribution reweighting, and criteria context distillation. This matters because it swaps coarse verdict-level supervision for dense token-level guidance, raising the multi-domain performance ceiling for generative judges.

Reinforcement Learning on Mixed-domain preference data (Mix-RL) has become the mainstream approach for training general-purpose Generative Reward Models (GRMs). However, Mix-RL suffers from two critical bottlenecks: the reward sparsity induced by outcome rewards, and the cross-domain interference arising from jointly optimizing heterogeneous capabilities, which together give rise to imbalanced capability acquisition and pervasive reward hacking. Inspired by the success of On-Policy Distillation (OPD) in multi-domain capability integration, we introduce RM-OPD (Reward Modeling via On-Policy Distillation), a two-stage framework that separates specialist acquisition from capability integration. First, we cultivate domain-specialized teacher models via single-domain GRPO fine-tuning, allowing each expert to reach its performance ceiling in isolation; then we consolidate these teachers into one student model through (i) routed on-policy distillation, which provides dense signed token-level supervision on student-generated critiques; (ii) domain contribution reweighting, which reweights token guidance toward target domain shares, preventing specific domains from dominating optimization; and (iii) optional criteria context distillation, which conditions teachers on domain-specific evaluation criteria to sharpen token-level supervision. Across multiple RM benchmarks and two base models, RM-OPD consistently outperforms vanilla Mix-RL and other strong baselines, achieving overall superior performance and exhibiting an emergent &#34;teacher-surpassing&#34; effect. These results establish RM-OPD as a promising paradigm for building generalist GRMs.
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cs.LGcs.CL Hyojung Han, Jongmin Kim, Seung-Hun Jeon · Oct 14, 2026

Data-quality gates conflate within-region example selection with across-region mass redistribution, so a gate-versus-random comparison cannot isolate what improved downstream performance. This paper introduces Counterfactual Gate–Support Decomposition (CGSD), a four-arm, budget-matched design that decomposes the gate effect into within-support selection $E$, between-support redistribution $S$, and their interaction $I$ by crossing eligibility and support-share factors. The core contribution is not the factorial algebra itself, but operationalizing it for finite pools while characterizing when the required arms are unrealizable.

A training-data quality gate changes both which examples survive within regions of the input space and how training mass is distributed across those regions, so a gate-versus-random comparison does not isolate these mechanisms. We introduce Counterfactual Gate-Support Decomposition (CGSD), a four-arm, budget-matched design that crosses gate eligibility with support distribution and decomposes the observed gate effect into within-support selection, between-support redistribution, and their interaction. The practical constraint is finite-pool realizability: we characterize mass and token-assembly conditions under which the required arms can be constructed, together with a support-extinction case in which the ordinary design is undefined. On Korean-English and Korean-Japanese retrieval, the mean within-support selection component is the only one that exceeds its calibrated null band (+29.7 and +5.6 holdout items; 30/30 positive replicates), decisively in Korean-English and marginally in Korean-Japanese; redistribution and interaction remain unresolved at the available power. The same pattern holds for a second, unrelated gate family -- a model-confidence threshold rather than a deterministic verifier -- judged against its own null (+27.3 items, 9/9 positive), so the result is not a property of one gate's mechanism. On a mathematics gate, zero-eligibility supports leave the ordinary design undefined at every budget, while the extended design is constructible only inside narrow budget bands that an exhaustive scan locates and that the natural operating point misses -- the assembly condition separating a property of the pool from a limitation of the packer. CGSD therefore returns a decomposition, a constructible-but-underpowered design, or an explicit non-constructibility result, and says which; it prevents support redistribution from being silently interpreted as sample-level gate quality.
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cs.CLcs.LG Kutay Tire, Atula Tejaswi, Haris Vikalo et al. · Oct 14, 2026

INTACT attacks the inference cost of chain-of-thought reasoning by replacing early textual reasoning steps with compact continuous latent vectors while keeping the backbone LLM frozen. A small 107M-parameter encoder iteratively builds a latent prefix from the frozen model's own hidden states, first distilling the effect of written reasoning steps and then refining via group-relative policy gradients. Across Llama and Qwen backbones from 1B to 8B, the method improves accuracy and shortens generation length, and a single encoder trained on math, science, and code transfers to twelve held-out benchmarks including commonsense without adaptation.

Latent reasoning replaces natural-language chains of thought with compact continuous &#34;soft-token&#34; representations, reducing the number of intermediate tokens that must be decoded autoregressively. We use a small external encoder to induce latent reasoning in a frozen backbone model. The encoder iteratively maps the backbone's hidden states to new latent blocks, constructing a latent reasoning prefix, after which the frozen model writes its remaining reasoning and its answer as text. Our method, INTACT, trains this encoder through distillation to reproduce the effect of written reasoning steps while keeping the model's behavior close to that of the frozen backbone, and then reinforces it on answer correctness. Across four frozen backbones from 1B to 8B, INTACT improves both GSM8K and average out-of-domain accuracy, including GSM8K gains from 75.8% to 79.3% on Llama-3.2-3B and from 77.6% to 79.7% on Qwen2.5-3B. It also reduces end-to-end latency per problem by 19% on Llama-3.2-3B and outperforms the evaluated latent-reasoning baselines at the 3B and 8B scales. Beyond the mathematics setting, the same recipe trained on a multi-domain corpus improves the frozen backbone on twelve evaluation benchmarks spanning mathematics, science, and commonsense, without task-specific adaptation.
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cs.CLcs.LG Yingfa Chen, Xingyu Shen, Chaojun Xiao et al. · Oct 14, 2026

Long-context LLM inference is bottlenecked by expanding key-value caches. This paper proposes treating the KV cache as a learnable layer and optimizing it per document via test-time training while keeping model weights frozen. The two-stage procedure first matches teacher attention statistics and then distills teacher predictions, yielding large accuracy gains on synthetic and natural-document benchmarks under aggressive compression.

Long contexts enlarge key--value (KV) caches, increasing memory use and attention costs during generation. Compressing these caches must preserve information for unseen questions. We introduce **Latent Compaction**, which learns a compact document-specific cache through test-time training. We initialize cache entries using reconstruction importance, teacher attention, and key-space diversity. Training first fits attention outputs and log-normalizers to those of the full cache, with reconstruction-selected entries held fixed. It then jointly optimizes the entire cache through end-to-end distillation from the full-cache model. Model weights remain frozen throughout, and training uses only generic prompts about the document, without access to downstream questions or answers. Experiments on RULER, LongBench, and Phonebook Lookup demonstrate substantial gains over budget-matched compression baselines. On a RULER, for example, our method achieves 96.7% accuracy at 32$\times$ compression, compared with 40.0% for KVZip+. The method also transfers across model scales and families, with retrieval gains on both Qwen3 and MiniCPM5. These results show that treating the KV cache as a neural network and optimizing it with test-time training can preserve retrieval accuracy under aggressive compression. The code is released at https://www.github.com/THUNLP/latent-compaction