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cs.AIcs.LGeess.SY Emile Anand, Mohammed Rehan Parwani, Xinyuan Cao · Oct 20, 2026

Multi-token prediction (MTP) accelerates language model decoding by drafting several future tokens in one forward pass, but the speculation horizon must be fixed before drafting and the best length varies with context. This paper frames horizon selection as an online survival problem: it predicts per-position rejection hazards to forecast how long a draft prefix will survive exact verification, then adaptively picks the horizon maximizing expected tokens per second. The resulting controller, AMTP, requires no retraining, leaves the target verifier unchanged, and comes with a sublinear throughput-regret bound against the best horizon at each visited context.

Multi-token prediction (MTP) can accelerate language-model decoding by drafting several tokens and verifying them in a single target-model pass. However, the best speculation horizon changes with context: longer drafts offer greater amortization when reliable, but can waste compute on suffixes discarded after a rejection. Unlike autoregressive drafting, where a stopping rule can decide token by token, MTP must fix the horizon before drafting, as all heads fire in the same forward pass. We therefore formulate horizon selection as an online control problem, using verification feedback to learn how far the draft can be trusted in each context, and introduce Adaptive Multi-Token Prediction (AMTP): a lightweight controller that requires no retraining and leaves the exact verifier unchanged. To guide horizon selection, we characterize the expected number of tokens committed at each horizon via acceptance survival, the probability that a draft prefix is fully accepted. Before each round, AMTP predicts how far the draft is likely to survive and picks the horizon with the highest expected tokens per second, learning freely from every verification pass. Theoretically, we show that any online learner's prediction error translates into throughput regret against the best horizon for each context, and in turn into a bound on wall-clock completion time. With online gradient descent, this regret is sublinear. Across five draft-target pairings built on Llama-3.1-8B-Instruct with Medusa heads, Meta's MTP models, and Qwen3-4B-Inst-2507-MTP, evaluated on AIME 2025 and GSM8K, AMTP decodes up to 4.1x faster than standard decoding and matches or outperforms the fixed window in 8 of 10 settings, with throughput gains of up to 10%.
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cs.CVcs.LGcs.RO Yunfei Xie, Howard H. Qian, Shiyi Lan et al. · Oct 22, 2026

Evaluating robotic foundation models still relies on expensive closed-loop rollouts in simulation or reality. This paper proposes Sensorimotor Alignment ($S^2$), a training-free offline metric inspired by the Platonic Representation Hypothesis, which scores how well a model's sensory embeddings align with the geometry of recorded end-effector trajectories. The authors find positive correlations between $S^2$ and task success across vision-language-action models, raw vision-language models, world action models, and real-robot policies, and argue the metric can cheaply rank models and diagnose representation-level behavior.

Robotic foundation models are typically evaluated through costly closed-loop rollouts, which motivates cheap offline proxies for model capability. The Platonic Representation Hypothesis (PRH) suggests that as representations improve, different modalities such as vision and language converge toward a shared statistical model of reality. We ask whether motion trajectories form another such modality: as embodied models become more capable, should their sensory representations converge toward the structure of physical motion? To examine this, we propose Sensorimotor Alignment ($S^2$), a training-free offline metric that measures how well a model's sensory representation aligns with the geometry of physical motion. We find that $S^2$ correlates positively with downstream robot task success across embodied model families, making it a low-cost offline proxy for prioritizing models before closed-loop evaluation. $S^2$ can also identify promising vision-language model (VLM) backbones even before costly fine-tuning into vision-language-action models (VLAs). Beyond this correlation, $S^2$ offers representation-level explanations for phenomena observed in VLAs and world action models (WAMs). With $S^2$, we extend PRH to embodied models and make sensorimotor alignment empirically measurable, offering insight into why an embodied model succeeds beyond its closed-loop success rate.
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math.NAcs.LGcs.NA Xin He, Huan Lao, Xiliang Lu et al. · Oct 22, 2026

This paper studies P-trainable neural networks, where a proportion P of hidden neurons are trainable and the rest stay fixed as random features, bridging random feature methods and fully trainable networks. The authors establish two-layer approximation bounds showing that a small trainable fraction can capture most of the gain when initialization mismatch is large, yielding a phase transition in rates of the form $\mathcal{O}(((P/\kappa_1^*+(1-P)/\kappa_0^*)m/\log m)^{-\alpha})$. They verify these assumptions explicitly for spherical biased-ReLU features and present numerical experiments showing analogous phase transitions in training losses across architectures with up to 15 layers.

Constructing accurate and computationally tractable approximation spaces is a fundamental task in scientific computing. Partially trainable neural networks bridge fixed random features and fully adaptive representations. This paper quantifies a phase transition pattern in approximation bounds and observes analogous behavior in training errors: a rapid but smooth initial improvement followed by diminishing returns, with a sharper transition under greater initialization mismatch. Under polynomial spectral decay with exponent $\alpha>1$ and leverage compatibility, we establish a squared $L_2$ approximation rate $\mathcal{O}((\kappa_P\log(m/\delta)/m)^\alpha)$ for two-layer networks of width $m$ and trainable proportion $P$, where $\kappa_P=(P/\kappa_1^*+(1-P)/\kappa_0^*)^{-1}$. The bound holds uniformly over the unit ball of a reproducing kernel Hilbert space (RKHS) with probability at least $1-\delta$. The constants $\kappa_0^*$ and $\kappa_1^*$ quantify the fixed and trainable groups' sampling mismatches relative to the target RKHS. For spherical biased-ReLU features in dimension $d$, we verify these assumptions with $\alpha=(d+2)/(d-1)$ and $\kappa_0^*=4\sqrt{2}\tau(d+1)/d$ for initialization scale $\tau\ge1$, and $\kappa_1^*=1$ under ridge leverage sampling. For $d=5$ and $\tau=10$, a trainable proportion of approximately $4.1\%$ captures $90\%$ of the reduction in the approximation bound from $P=0$ to $P=1$. A structured three-layer example illustrates how a few trainable first-layer neurons exploit fixed downstream blocks through nonlinear composition. Numerical experiments across diverse settings, including networks with up to 15 layers, exhibit similar phase transitions in training errors.
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stat.MLcs.LGstat.ME Isaac Gibbs, Elise L. Han, Ryan J. Tibshirani et al. · Oct 22, 2026

AI systems increasingly make consequential decisions, but fully auditing every output is infeasible at scale. This paper studies selective auditing: sequentially deciding when to trust an AI decision versus escalate it to an expert, using only a scalar confidence score. The authors frame this as an online constrained optimization problem and derive algorithms that guarantee the fraction of unaudited errors stays below a user-specified threshold α without any distributional assumptions. The core contribution is an optimally efficient algorithm that provably minimizes audit effort for both adversarial and i.i.d. data streams.

We consider online monitoring of an AI system that produces a sequence of decisions. At each round, the system outputs a proposed decision together with a confidence score estimating the trustworthiness of the decision. The decision and confidence score need not be produced by the same model: for example, one agent may propose a decision, while a separate verifier agent evaluates it and outputs a correctness or safety score. Based on this information, we must decide whether to accept the AI decision automatically or consult an expert, such as a human auditor, who reviews the proposal and either accepts or corrects it. We formulate this task as an online constrained optimization problem in which the goal is to minimize the frequency of expert auditing while guaranteeing that the fraction of AI errors that go unaudited stays below a user-defined threshold. We derive a family of algorithms with provable error-control guarantees with no assumptions, including a method that is optimally efficient: it asymptotically attains the best achievable auditing rate for both adversarial and i.i.d. data streams. Experiments on screening harmful requests to large language models, qualitative text annotation, and data labeling show that our methods achieve valid error control in practice while substantially reducing the need for human auditing compared to baselines.
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cs.CVcs.LG Sy-Tuyen Ho, Anirudh Satheesh, Soham Chawathe et al. · Oct 22, 2026

Dataset-use auditing for text-to-image models is difficult because fine-tuned models absorb collection-level visual style without reproducing individual training images. SpectralCanary addresses this by blending a fixed canary image into the low-frequency Fourier content of every collection image before release, preserving captions and avoiding auxiliary generation or per-image optimization. A lightweight verifier then detects the transferred spectral signature in a suspect model's black-box outputs. The method achieves strong detection rates across multiple architectures and domains with minimal fidelity loss, establishing low-frequency traces as a practical auditing mechanism.

Auditing whether a text-to-image (T2I) model was fine-tuned on a particular image collection is difficult: a model can absorb collection-level visual characteristics without reproducing training images. Proactive dataset-use auditing plants a shared signal in a dataset before release, then later checks whether that signal appears in a suspect model's generated outputs. Existing approaches often trade off verifiability, fidelity, robustness, and deployability. We introduce $\textbf{SpectralCanary}$, which uses a smooth low-pass mask to blend a fixed canary image into every collection image while leaving captions unchanged and requiring neither auxiliary generation nor per-image optimization. A lightweight verifier detects the transferred signal in suspect-model outputs. Across eight tests on the Pokemon dataset and three realistic data transformations, spanning two architectures families, SpectralCanary achieves the highest average per-generation TPR@$1\%$ FPR ($91.1\%$) and fixed threshold model-level accuracy using 30 generations ($94.8\%$) among the evaluated methods. Across five datasets spanning artistic, medical, satellite, and fashion domains with SD3.5, SpectralCanary averages $92.4\%$ per-generation TPR@$1\%$ FPR while preserving the released images (SSIM $0.989$, LPIPS $0.022$) with a near-zero mean change FID (mean $\Delta$FID $0.05$) across datasets. Matched-energy ablations on Pokemon and ROCOv2 support our design choice, low-frequency placement transfers more reliably compared to mid/high-frequency placement. Under the evaluated adaptive attacks, the most effective removal requires aggressive modification and incurs more than $25$ $\Delta$FID points. These results identify low-frequency visual signals as effective carriers for collection-level T2I audit traces.
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cs.LG Jonathan T. Barron, Dan Gnanapragasam, Michael Tschannen · Oct 22, 2026

Standard softmax and cross-entropy hide two floating-point bugs: Softmax Collapse rounds the target gradient to zero once logit margins cross a precision cliff, while Softmax Cancellation produces phantom gradients when a student network approaches its teacher. Barron et al. rewrite both functions in log-space using softplus, expm1, and log1p to recover accurate, zero-sum gradients across bf16, fp32, and fp64. They tie these numerical issues to the Slingshot phenomenon in grokking and derive a clean equilibrium for logit margins under AdamW with weight decay.

Standard implementations of softmax, log-softmax, and cross-entropy have two numerical bugs. The first bug, Softmax Collapse, rounds the target logit's gradient to zero if that one logit is much larger than the others, resulting in gradients that no longer sum to zero. The second bug, Softmax Cancellation, occurs when student logits are close to teacher logits, and produces non-zero gradients even when the student and teacher logits are equal. We present simple implementations of log-softmax, softmax, and cross-entropy that fix both bugs. Our fix eliminates the previously-observed "Slingshot" phenomenon, speeds up grokking with weight decay, prevents accuracy collapse without weight decay, stops student networks from drifting away from the teacher during distillation, and shows that after memorization, logit growth is bounded by an equilibrium between weight decay and Adam's $\epsilon$ hyperparameter.
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cs.LGstat.ML Yuxuan Cai, Yuan Cao · Oct 22, 2026

This paper asks whether transformers that generate intermediate reasoning steps can discover new algorithms beyond the teacher they are trained to imitate. It designs a two-stage training protocol for in-context linear regression—first supervised by gradient descent, then by ground-truth weights—and proves that a one-layer linear self-attention transformer learns the Heavy-Ball method. The result matters because it gives a rigorous case where chain-of-thought reasoning internalizes acceleration rather than simply memorizing the supervised update.

Modern transformers often solve complex tasks by generating and refining intermediate reasoning steps. To develop a theoretical understanding of chain-of-thought (CoT) reasoning, a notable recent study by Huang et al. (2025) viewed transformers as algorithm executors, and showed that when transformers' CoT steps are supervised by a gradient-descent teacher, they can learn to implement gradient descent for in-context weight prediction in linear regression. In this paper, we study the same in-context weight prediction task but ask whether CoT reasoning can go beyond merely imitating the teacher algorithm. We show that, after initial supervision from a gradient-descent teacher, further trajectory-level supervision using the true regression weights leads the model to implement the Heavy-Ball method, thereby achieving acceleration over the original teacher. Notably, this accelerated algorithm emerges without supervision from any Heavy-Ball teacher. Our results provide a concrete theoretical example in which transformer reasoning can discover new algorithms through training, rather than merely imitate the algorithm used for supervision.
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cs.LG Hayden Prairie, Jacob M. Ryan, Taylor Berg-Kirkpatrick et al. · Oct 22, 2026

Looped language models reuse the same parameter block many times to improve quality without inflating weight memory, but each recurrence still stores its own KV-cache, so inference memory grows linearly with depth. This paper studies when and why the final recurrence's KV-cache can be shared across earlier recurrences—a property the authors call KV-shareability—finding that contractive residual dynamics are necessary but not sufficient. They introduce a two-stage recipe (stochastic-depth pretraining plus a lightweight post-training corrector called BeNice!) that reliably enables near-lossless KV-sharing and composes with existing cache-compression techniques.

Looped architectures scale quality while keeping parameter count fixed by repeatedly passing activations through the same block of layers. During inference, each recurrence generates independent KV-caches, causing memory to grow linearly. To address this challenge, prior work has proposed KV-sharing (i.e., sharing KV-caches across depth), finding that, in some cases, the KV-cache of the final recurrence can be shared with the earlier recurrences without quality loss, a property we denote as KV-shareability. However, the mechanisms underlying KV-shareability remain poorly understood, with even identically trained looped architectures not consistently exhibiting it. In this paper, we study how KV-shareability can be enabled in looped models. We propose a two-stage method: in the first stage, we use stochastic depth during pretraining, which induces contractive residual dynamics that drive representations toward a common limit across recurrences. In the second stage, we propose BeNice!, a post-training method that broadcasts the final recurrence's KV-cache into the first recurrence, training it to produce compatible residuals while preserving the original model's quality. As a result, BeNice! enables KV-shareability while matching standard finetuning's unshared validation perplexity. Using BeNice!, we show that KV-sharing is complementary to alternative KV-compression methods, composing with memory-efficient sequence mixers (e.g., multi-latent attention, Kimi delta attention) and low-precision KV-cache quantization (e.g., fp8, mxfp8, nvfp4). Finally, in simulated low-memory, long-context inference, KV-sharing improves cache hit rates by up to 31.4%, increases throughput by up to 23.6%, and reduces p90 time-to-first-token by up to 83.6%.
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cs.CVcs.LG Jihoon Hong, Alireza Kheirandish, Rohan Sanda et al. · Oct 22, 2026

Local anomaly detection in images with multimodal inlier distributions—such as medical scans, faces, and X-ray baggage—remains challenging for industrial-defect methods that rely on heuristic reconstruction errors or feature distances. LACToS introduces a principled alternative by scoring superpixels via statistical typicality under the conditional inpainting posterior of an inlier diffusion model, made tractable by grouping pixels into superpixels and using a single denoising posterior as a cheap proxy. This shift from point estimates to distribution-aware testing matters because it directly addresses the false positives that arise when normal images contain diverse, context-dependent content.

Local anomaly detection is the task of identifying spatially confined anomalous or out-of-distribution (OOD) regions within an otherwise in-distribution (ID) image. Most existing methods are designed for a specific context, with a strong focus on industrial defect detection, where they achieve excellent performance on well-established benchmarks. However, we observe that these methods can exhibit significant performance drops in other contexts, especially when the inlier distribution is multimodal. To account for this inlier complexity, we propose LACToS, a principled local OOD detection method based on statistical typicality and made tractable through two innovations: (i) grouping pixels into superpixels and (ii) using a computationally efficient proxy to estimate typicality. We evaluate LACToS across three diverse applications spanning medical imaging, human faces, and X-ray security screening. LACToS performs more robustly than prior methods across these benchmarks. The code is released here: https://github.com/voilalab/LACToS.
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cs.LG Franco Rugolon, Ioanna Miliou, Panagiotis Papapetrou · Oct 22, 2026

CRANE addresses the lack of post-hoc counterfactual explanation methods for multimodal classifiers, where applying unimodal techniques independently produces incoherent, chimeric explanations that violate cross-modal constraints. The framework retrieves real training instances from the target class via several nearest-neighbour strategies, most notably Multimodal Consensus Retrieval (MC-R), which intersects per-modality neighbour sets to preserve joint distributional coherence. By operating without model internals for most strategies and grounding explanations in observed data, CRANE aims to deliver plausible, actionable counterfactuals across heterogeneous inputs including text, images, tables, and time series.

Counterfactual explanation methods have been introduced for unimodal settings, with dedicated frameworks for tabular, timeseries, text, and image data, yet no post-hoc method has been designed for classifiers that learn from multimodal inputs. Existing explainability methods for multimodal classifiers apply modality-specific attribution independently to each input, which fails to yield coherent explanations and does not transfer to arbitrary pre-trained multimodal architectures. To address these shortcomings, we present CRANE (Counterfactual Retrieval via Agnostic Nearest-neighbour Explanations), the first post-hoc, model-agnostic framework for nearest-neighbour multimodal counterfactual generation that retrieves real training examples from the target class as candidate explanations, ensuring plausibility by construction. Across four heterogeneous datasets and three fusion strategies, we show that Multimodal Consensus Retrieval (MC-R), which intersects per-modality neighbour sets to identify instances jointly close to the query in every modality, emerges as the strongest multimodal strategy, achieving the best or joint-best outcome on three of four datasets while grounding every explanation in the joint training distribution. Unimodal strategies remain competitive when a single modality dominates the decision boundary.
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cs.LGcs.CR Qi Li, Xinchao Wang · Oct 22, 2026

On-policy self-distillation trains language models by distilling privileged self-supervision over the model's own rollouts, yet its privacy risks have remained almost entirely unexplored. This paper presents the first study of membership inference attacks against such systems, showing that the training imprint is sparse and concentrates on uncertainty-sensitive reasoning tokens rather than spreading uniformly across outputs. The authors propose OP-Print, a unified gray-box and black-box attack framework that either aggregates privileged teacher-student residuals directly or infers them from restart-based output-basin stability. Their empirical results suggest that on-policy self-distillation introduces a distinct, previously overlooked privacy leakage surface that conventional MIA heuristics fail to capture, raising important concerns for privacy auditing of modern post-training pipelines.

On-policy distillation has been widely adopted for alleviating the distribution mismatch of off-policy distillation. Self-distillation further removes the need for an external teacher by using the student's own outputs, enhanced with extra context or demonstrations, as supervision. This teacher-free design makes on-policy self-distillation practical, yet its privacy risks remain largely unexplored. In particular, using two coupled views of the same training example may strengthen its memorization. Motivated by this, we present the first study of membership inference attacks against on-policy self-distillation. We investigate both gray-box and black-box threat models and propose a unified attack framework, named OP-Print. OP-Print builds on our finding that the supervision imprint in on-policy self-distillation is sparse and structured, concentrating on uncertainty-sensitive correction sites rather than across the entire rollout. Exploiting this property, we construct attack signals tailored to the two access levels: in the gray-box setting, OP-Print directly aggregates the privileged teacher-student residual correction along the same rollout; in the black-box setting, it measures restart-based output-basin stability as an observable surrogate for the hidden correction process. Across diverse models and distillation schemes, all baseline attacks remain essentially at random guessing even under gray-box access, whereas OP-Print is broadly validated to be effective in both gray-box and black-box settings.
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stat.MLcs.LG R\'emy Chapelle (CB, EVDG, CESP) · Oct 22, 2026

High-dimensional nonparametric density estimation is notoriously plagued by the curse of dimensionality. This paper proposes to factorize the joint distribution autoregressively into a product of one marginal and $d-1$ conditional densities, estimating each factor with parallel gradient boosting (PGB), a fast tree-based multi-quantile regression method. The authors prove that for subadditive divergences the joint convergence rate is governed by the hardest factor, and that when conditional estimators adapt to sparsity the optimal rate relates to the treewidth of an underlying dependence graph. Together, the theory and experiments suggest that flexible autoregressive factorization offers a practical off-the-shelf alternative to kernels, copulas, and random forests for moderate-to-high dimensional continuous data.

Nonparametric estimation of joint probability distributions is a core problem in statistics, which is notoriously challenging with high-dimensional data. Such challenges also arise with conditional distribution estimation and have led to flexible algorithms that aim to tackle the ''curse of dimensionality'' by exploiting predictive structures of lower dimension than the ambient space. In this paper, we study the use of such conditional distribution estimators to estimate joint distributions by factorizing the latter in an ''autoregressive'' way. We show that for loss functions satisfying a subadditivity property, bounds on the convergence rate of an autoregressive estimator can be derived from bounds on the convergence rate of the conditional distribution estimators. These bounds relate the difficulty of estimating the joint distribution to that of estimating the most challenging factor in the autoregressive factorization. When the conditional estimators adapt to sparsity in their conditioning sets, we characterize this difficulty through variable elimination in an undirected dependence graph. This allows bounding the rates of convergence by quantities related to the sparsity of the graph, and provides an additional motivation for the autoregressive approach. We then evaluate the practical performance of an autoregressive estimator based on parallel gradient boosting, a flexible nonparametric method for estimating conditional distributions. The estimator demonstrates competitive estimation performance on various simulated and real datasets, even without optimizing the factorization order. Together, these results support nonparametric autoregressive estimation as a practical approach to flexible joint distribution estimation.
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cs.LG Sarah Liaw, Yuanqi Du, Yilun Du · Oct 22, 2026

Scientific inference often requires evaluating and optimizing complete trajectories, yet existing methods typically learn local one-step dynamics or train black-box generators that lack a reusable path objective. This paper proposes action learning, the task of recovering a stochastic action from trajectory observations, and introduces LEAP, which learns a path-space correction relative to a tractable reference process via noise-contrastive trajectory comparisons. By constructing a differentiable objective on complete paths, LEAP captures nonadditive temporal dependencies and enables downstream reuse for ranking, constrained inference, and sampling without retraining.

Understanding and controlling how systems evolve is central to science and engineering, where many problems require reasoning about complete trajectories. Existing approaches typically learn local dynamics or generate trajectories, but objectives constructed from individual transitions can miss dependencies across time, while generative models do not necessarily provide a tractable objective for evaluating and optimizing arbitrary paths. We study $\textit{action learning}$, the problem of recovering a stochastic action from trajectory observations, yielding a common objective for reasoning about dynamical systems. We introduce $\textbf{LEAP}$ ($\textbf{L}$earned $\textbf{E}$nergy on $\textbf{A}$ction $\textbf{P}$aths), which anchors the unknown action to a tractable reference process and learns the remaining correction by comparing observed trajectories with reference trajectories. This construction yields a differentiable objective on path space that can capture both local dynamical structure and nonadditive dependencies across time. Once learned, the same action can be flexibly reused for path ranking and inference, mechanism steering, constrained optimization and sampling. Across stochastic physical systems, many-body orbital dynamics and molecular simulations, LEAP recovers underlying dynamics, captures dependencies across time and enables transfer across inference objectives and physical conditions. We show that $\textit{action learning}$ is a promising framework for turning trajectory observations into reusable objectives for scientific inference and control.
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cs.CEcs.LGcs.NA Miguel A. Aguilo · Oct 22, 2026

The paper presents structure-preserving reduced-order models for two high-speed aeroelastic challenge problems—a clamped panel at Mach 1.92 (RC-19) and a cantilever plate at Mach 5.85 (HyMAX). Because the experimental packages lack time-resolved responses or repeated runs, the author proposes a learned model that retains the exact physics-based potential energy, fits generalized aerodynamic and damping forces by least squares, and trains only a dissipation matrix engineered to remain positive definite. An exact discrete-gradient integrator then guarantees an energy balance to machine precision regardless of the trained parameters, aiming to show that physical structure, not large datasets, can carry predictive capability in chaotic flutter regimes.

We build structure-preserving reduced-order models for both challenge problems of the AePW-4 High-Speed Working Group. They are a clamped thin panel at Mach 1.92 (RC-19) and a cantilever plate at Mach 5.85 (HyMAX). The published data for each case hold no time-resolved response and no repeated runs. The physics must therefore be carried by the form of the model. One construction gives two models per problem. A Ritz-Galerkin reference model describes the plate. A learned model keeps the reference model's exact potential, fits the remaining generalized forces, and trains only a dissipation that cannot add energy. Its energy balance holds for any weights by construction. On the trained model the worst relative residual is 2.2e-15. On RC-19, shock relations predict a pressure ratio of 1.521 across the panel. Pressure-sensitive paint measured the same value. Thirty runs of the learned model place the mean dominant frequency within 1.0% of the measured 236 Hz. At one periodic and one chaotic condition, the learned model reproduces the response regime of a published reduced-order model in all sixteen runs. It does so without that model's 113 Hz spectral peak, which the measurements do not show. Measured displacements can also correct the chaotic response through one more force that respects the energy balance. We tested this on synthetic data at the experiment's 5 kHz sampling rate. The state error is 1.25% of the panel thickness without noise and 3.5% with 10 micrometers of noise. On HyMAX the learned model follows the reference model's trailing-edge displacement for 65 ms with a relative error of 3.7%. These results show that a model whose structure carries the physics can match measured flutter behavior when the available data cannot train it.
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cs.LG Sihan Yang, Jie Huang, Hanxuan Li et al. · Oct 22, 2026

Sequence compression is a critical bottleneck in efficient language and multimodal models, yet most architectures rely on simple pooling or MLP projections that ignore inter-token correlations. This paper reframes compression as a test-time ridge regression problem: input tokens define a regression whose fitted coefficients become the compressed vector. The resulting TTR-Compressor solves exactly in closed form via a small Cholesky factorization, introduces only $2d$ learnable parameters, and yields strong gains on long-context retrieval and visual token merging.

Sequence compression is a fundamental operation and a critical information bottleneck in efficient language and multimodal models, and yet prevailing approaches based on pooling or learned projections remain underperforming. We revisit sequence compression through the lens of test-time regression: input tokens define a regression problem whose fitted coefficients form the compressed representation. Importantly, the regression problem is learned end-to-end via backpropagation, while its coefficients are computed efficiently in closed form during the forward pass. This leads to TTR-Compressor, a general alternative to conventional pooling and projection-based compression. We evaluate TTR-Compressor as the compressor for block-wise sparse attention and the visual token merger for multimodal large language models. On block-wise sparse attention, TTR-Compressor improves RULER performance over attention-based compressors by a large margin. For visual token merging, it consistently outperforms the standard MLP merger and matches its performance with 55.6% fewer visual tokens. These results establish test-time regression as an effective primitive for sequence compression in efficient language and multimodal models.
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cs.LG Andrea Giuseppe Di Francesco, Rishabh Jain, Franco Maria Nardini et al. · Oct 22, 2026

Graph soft prompting methods such as G-Retriever claim to inject relational graph knowledge into LLMs via learned continuous tokens, yet it remains unclear whether these tokens actually carry graph-specific information. This paper identifies and systematically investigates a pathological failure mode called token collapse, in which graph-derived tokens become nearly identical across inputs, effectively degenerating into generic soft prompts. Through causal interventions across three benchmarks, multiple graph encoders, and two LLM families, the authors show that strong task accuracy can conceal a token interface that the model does not meaningfully use, and they propose a diagnostic protocol to evaluate graph-token alignment beyond simple accuracy.

Recent methods for injecting graph structure into LLM prompts include graph soft prompting, in which a graph neural network (GNN) learns graph-specific tokens that capture relational information among entities in textual prompts. G-Retriever combines graph soft prompts with a verbalized description of the same graph to strengthen the textual prompt signal. We conduct an in-depth analysis of G-Retriever and uncover a pathological behavior we term token collapse. Across three benchmarks, three graph encoders, two LLM families, and both frozen and LoRA-adapted models, G-Retriever's graph tokens become almost indistinguishable across inputs. We provide evidence that the same failure is inherited by subsequent methods, even with multi-token pooling. Under the standard setup, swapping a token with the dataset mean, a token from another example, or one derived from a corrupted graph produces no resolved answer-level effect in accuracy. Moreover, a learned constant prompt that never accesses the graph matches or surpasses G-Retriever on all three benchmarks. These findings indicate that, rather than conveying graph content as intended, the collapsed token functions primarily as a generic soft prompt. We also examine conditions linked to this collapse and propose a two-stage procedure that yields non-collapsed tokens while maintaining competitive performance in most cases. However, token variability alone does not prove that the model uses graph information: via interventions and decoding probes, we show that depending on the configuration, a token can reflect the question, an answer prior, or graph-derived content that the LLM may or may not use. Overall, our results offer a practical approach to evaluating graph-token alignment rather than inferring it from task accuracy alone. Code to reproduce our experiments is available at https://github.com/difra100/Token_Collapse_KGQA.
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cs.LGcs.DC Kyrylo Yemets, Andrii Yaroshevych, Victor Muryn et al. · Oct 22, 2026

Apple Silicon dominates local LLM inference, yet nearly every published optimization is designed and benchmarked on NVIDIA server GPUs under batched serving workloads. This paper asks which speedups survive when moved to single-request, unified-memory Apple machines, evaluating four families—KV-cache pruning, speculative decoding, ported CUDA kernels, and post-training quantization—across four Apple devices with matched RTX 4090 controls. The central finding is that a reported speedup is not an intrinsic property of a technique but a joint function of technique, runtime, hardware contract, and workload regime.

Apple Silicon is among the most widely used platforms for local LLM inference, yet nearly all inference optimizations are designed and validated on server-class NVIDIA GPUs under batched serving workloads. Which optimizations retain their benefits when moved to Apple Silicon, and what determines their applicability? We evaluate four optimization families: KV-cache pruning, speculative decoding, ported GPU kernels, and post-training quantization. Experiments span four Apple machines under a common single-request decode workload, with matched RTX 4090 comparisons where possible. KV-cache pruning can reach up to 1.75 times end-to-end throughput on Apple but can reduce throughput on desktop NVIDIA GPUs. Under the common benchmark, all evaluated speculative decoding methods reduce throughput on Apple, despite reported 2-6 times gains on server GPUs. CUDA kernel designs transfer only partially: public Metal lacks asynchronous copy, and batch-one decode makes several serving-oriented mechanisms inapplicable, although transferable components yield up to 1.20 times decode throughput. Quantization gains vary by machine. Across four families, a reported speedup is not a portable property of a technique alone but a joint function of technique, runtime, hardware contract, and workload regime.
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cs.CVcs.LG Chuang Chen · Oct 22, 2026

RaSFNet tackles LiDAR semantic segmentation by fusing 3D point features with 2D frustum features in a projection-based pipeline. Its three proposed modules—RAGDE for ray-aligned geometric encoding, STAM for azimuth-aware global context via a scan-serpentine Mamba, and RCPFF for range-constrained cross-representation fusion—are designed to resolve projection conflicts and preserve 3D spatial correspondence. The method reports $70.2\%$ mIoU on the SemanticKITTI validation set and $77.7\%$ on the nuScenes validation set.

LiDAR point cloud semantic segmentation is a fundamental component of 3D perception for autonomous driving and robotics. Projection-based methods map 3D point clouds into 2D representations for feature extraction using 2D networks. However, aggregating multiple points during projection can obscure geometric differences within each frustum, while local feature extraction limits the modeling of spatial relationships across scanning regions. Moreover, proximity in the projected representation does not necessarily imply proximity in 3D space, and interactions between point and projected features may mix features from different ranges, reducing semantic discriminability. To address these challenges, we propose the Ray-aligned and Scan-aware Fusion Network (RaSFNet), which incorporates point cloud geometry and LiDAR scanning characteristics into projection-based semantic segmentation. Specifically, the Ray-Aligned Geometric Distribution Encoding (RAGDE) module characterizes point distributions within each frustum using a ray-aligned coordinate system. To model spatial context, a Scan-Topology-Aware Mamba (STAM) block organizes frustum features according to the LiDAR azimuth sampling pattern and captures long-range dependencies across scanning regions. In addition, a Range-Constrained Point-Frustum Fusion (RCPFF) mechanism uses shared range information to guide feature exchange between point and frustum representations while maintaining spatial correspondence. RaSFNet achieves mIoU scores of 70.2% and 77.7% on the SemanticKITTI and nuScenes validation sets, respectively, indicating competitive segmentation performance compared with the evaluated methods.
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physics.data-ancs.LGhep-ex Shuhang Li, Haiwang Yu, Gabor Galgoczi et al. · Oct 22, 2026

Modern nuclear and particle physics detectors such as the sPHENIX TPC produce increasingly large, sparse data volumes that strain conventional reconstruction. This work evaluates FM4NPP, a ~200M-parameter Mamba-based foundation model pretrained on TPC spacepoint sequences via self-supervised $k$-Next-Nearest-Neighbor prediction, on downstream track finding and particle identification. The central claim is that a single frozen backbone with lightweight adapters can outperform a traditional Cellular-Automaton seeder at low momentum and match or exceed a Gaussian-Process-Regression $dE/dx$ baseline for PID, potentially extending physics reach while simplifying analysis chains.

Modern high energy nuclear and particle physics experiments produce large amounts of sparse data that must be reduced significantly in size before performing physics analysis. Recently, there has been an effort to evaluate Foundation Models as a potential tool for performing data analysis. These models have been shown to learn features in high dimensional datasets based on the multi-modal data they are trained on. To show their effectiveness at performing complex pattern recognition tasks, such as reconstructing charged particles in a magnetic field, we evaluated the performance of a Foundation Model based reconstruction on several downstream tasks with a dataset composed of spacepoints in a Time Projection Chamber. We show that the performance of the Foundation Model based data analysis significantly improves upon that of traditional methods, and furthermore can be adapted to learn additional tasks that are not necessarily related to the initial training objective.
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cs.CRcs.LG Jaishnoor Kaur, Josef Hor\'a\v{c}ek, Ian Waskom et al. · Oct 22, 2026

ReDence tackles the problem of detecting modern social engineering scams that go beyond credential phishing by performing adaptive, multimodal investigations of websites and their artifacts. Its core idea is a hybrid architecture that pairs a fine-tuned 4B-parameter agentic Investigator (Qwen3.5-4B) for reasoning and reporting with a specialized 4B-parameter Decider (Tev1) for fast binary and multiple-choice decisions, cutting latency while preserving depth. This matters because SE scams caused billions in losses in 2025 and existing detectors either lack interactive evidence gathering or are too slow to operate at scale.

Detecting online social engineering (SE) scams often requires examining website workflows, verifying claims against external sources, and connecting evidence across multiple pages. Existing detectors provide limited support for these investigations, leaving analysts to manually gather and validate evidence, which inevitably delays detection and subsequent takedown of these attacks. To address this gap, we present ReDence, an open-source hybrid framework for adaptive, evidence-grounded detection across diverse SE scam categories. ReDence combines two locally hosted models with complementary responsibilities: a fine-tuned multimodal agentic Investigator (Qwen3.5-4B) that performs investigative planning, evidence interpretation, and reporting, and a specialized Decider (Tev1) that handles binary and multiple-choice tasks, including browser-action selection, evidence assessment, and decisions about whether to continue an investigation. By delegating discrete decisions to a specialized model, ReDence reduces reliance on lengthy language-model responses, while preserving the reasoning capabilities required for complex investigations. Our evaluation demonstrates that ReDence achieves 96\% accuracy in detecting scams across twelve SE scam categories, substantially outperforming existing detectors while being at least four times faster than comparable agentic models without compromising investigative depth. ReDence also produces structured, evidence-grounded reports that document investigative actions, supporting and contradictory evidence, and collected artifacts, which allow analysts to independently audit detection decisions and utilize the collected evidence to support subsequent mitigation and takedown efforts.