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cs.LGcs.CV Yuan Huang, Zihan Chen, Runbin Zhang et al. · Oct 1, 2026

Continual learners that keep a task-specific adapter in every ViT block accumulate parameters linearly in the number of tasks. This paper asks which blocks should specialize, showing that exhaustive placement search traces an inverted-U curve peaking at intermediate depth, while cheap internal criteria systematically favor the deep but suboptimal layers. To sidestep expensive search, the authors propose LS-B, which observes the first few tasks through a frozen fMRI encoding model of human visual cortex and commits task-specific capacity to the blocks whose brain readouts vary most across tasks relative to their stable structure.

Continual learners that keep a task-specific adapter in every block of a pre-trained vision transformer accumulate storage linearly with the number of tasks; keeping task-specific adapters in only a few blocks curbs this growth but raises the question of where to place them. We investigate this question from two perspectives. Algorithmically, training all contiguous four-block placements yields an inverted U: final accuracy peaks at intermediate depth and varies by up to 3.5 percentage points (pp), while inexpensive criteria based on weight spectra or activation statistics favor the deepest blocks. From neuroscience, the hierarchical organization and intermediate-stage plasticity of the visual cortex motivate us to ask whether a measurement taken outside the learner can guide layer specialization without placement search. LS-B observes the first tasks through a frozen fMRI encoding model of twelve human visual areas and commits task-specific capacity once to the blocks whose readouts vary most across tasks relative to their stable structure. Across three ViT-B/16 backbones, LS-B yields stable, backbone-specific allocations. On the two backbones with placement search, AugReg and iBOT, the selected blocks overlap the intermediate-depth region identified by search. Under matched storage and observation budgets, the selected blocks outperform the shallowest and deepest four-block configurations. On Split ImageNet-R, LS-B uses 60% of full-BiLoRA adapter storage while remaining within 1.5 pp of its final accuracy. The allocation requires no labels or backpropagation, adds under 0.6% runtime, and exhibits backbone-specific cortical signatures.
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cs.AIcs.LGcs.LO Lu-Chin Chang, Suguman Bansal · Oct 1, 2026

Reinforcement learning for reachability specifications has been limited to model-based methods that explicitly estimate transition probabilities. This paper introduces Quasar, a model-free Q-learning variant that provably converges to optimal reachability policies on MDPs without non-terminal maximal end components, using only $O(|S||A|)$ memory. By replacing the missing discount factor with an intrinsic expected hitting time, the authors obtain a weighted contraction and demonstrate orders-of-magnitude sample improvements over the state of the art.

Reinforcement learning (RL) for reachability specifications is fundamental to sequential decision-making. Prior work establishes asymptotic convergence to optimal policies, but only through model-based methods that must explicitly estimate the transition probabilities of the underlying Markov Decision Process (MDP). We present Quasar, the first model-free algorithm with asymptotic guarantees for reachability on the fragment of MDPs free of non-terminal maximal end components (MECs), a building block to which every MDP reduces by the standard MEC quotient. Our algorithm follows the classical Q-learning approach, using temporal-difference updates to converge to an optimal policy without ever learning the transition probabilities. The resulting learner reduces the memory footprint from the O(|S|^2|A|) that model-based methods require to O(|S||A|). On the standardized Quantitative Verification Benchmark Set, our algorithm converges to the optimal policy with orders of magnitude fewer samples than the previous model-based state-of-the-art. Together these results are a concrete step toward the practical deployment of reachability learning and, with it, of specification-guided RL.
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cs.LGeess.IVq-bio.NC Emmanuelle Renauld, Philippe Poulin, Hugo Larochelle et al. · Oct 1, 2026

Iterative tractography must reconcile noisy local diffusion signals with globally plausible fiber pathways, yet standard deep learning models optimize only a local next-step loss. This paper tackles that gap by systematically evaluating RNN and Transformer architectures and introducing a generation-validation (GV) phase that supervises training at the streamline level via connectivity scores. It reports top scores on the ISMRM 2015 phantom and provides open-source models, while also arguing that current phantoms and in vivo evaluation tools are too limited for definitive benchmarking.

Machine learning (ML) has emerged as a promising approach for improving diffusion MRI (dMRI) tractography, a task that remains limited by the intrinsic tension between local diffusion information and global anatomical plausibility. In this work, we systematically evaluate recurrent neural networks (RNNs) and Transformer models for iterative tractography, with particular attention to training strategies, input representations (including convolutional neural network (CNN)-based embeddings and end-of-sequence (EOS) tokens), and hyperparameter selection. We introduce a generation-validation phase enabling supervision at the streamline level during training, allowing supervision despite the mismatch between local loss functions and global streamline quality. Using the ISMRM2015 tractography challenge dataset, our models achieve the highest reported performance to date. Through controlled experiments, we quantify the impact of missing bundles, noisy or imperfect training streamlines, and invalid fibers in the training set. Finally, we demonstrate the applicability of our best-performing models for in vivo data from the Tractoinferno database. Overall, our results highlight both the potential and the limits of sequence-based deep learning models such as Transformers and RNNs for tractography, and emphasize the need for improved phantoms and evaluation methods for in vivo validation. We provide takeaways and recommendations for future researchers training and validating sequence-based supervised methods for tractography.
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cs.NEcs.LG Eleni Nisioti, Andrea Cossu, Kathrin Korte et al. · Oct 1, 2026

Continual reinforcement learning demands a delicate balance between plasticity (learning new tasks) and stability (not forgetting old ones). This paper argues that neuroevolution—specifically evolution strategies (ES) and genetic algorithms (GAs)—offers a compelling alternative to gradient-based policy-gradient methods, which tend to lose plasticity as tasks change. Across a broad sweep of environments and task-shift types, the authors show that ES consistently achieves the best stability-plasticity trade-off, and they propose a clear mechanism: parameter-space exploration produces wider "neighborhoods" of robust solutions that overlap across sequential tasks. The work matters because it challenges the prevailing focus on fixing gradient-based RL and instead revives a classic optimization paradigm with strong empirical and conceptual justification.

Despite many studies about causes and remedies of plasticity loss in Reinforcement Learning (RL) under continual task changes, no RL method has yet consistently achieved a good balance between adaptation and forgetting. Here we turn to an alternative optimization paradigm, neuroevolution (NE): algorithms that search directly in weight space through mutation and selection over a population of neural networks. Across a wide array of environments and environmental changes, with policies ranging from a few hundred parameters to million-parameter networks, we compare evolution strategies (ES) and genetic algorithms (GAs) against state-of-the-art continual RL variants and population-based RL. ES most consistently achieves a good stability-plasticity trade-off, while the GA is the most plastic method but forgets more than ES. To explain this, we study the return landscape around each method's solutions. ES finds the widest neighborhoods, i.e.\ regions of weight space in which perturbed policies still solve the task, and the size of the overlap between the neighborhoods of consecutive tasks correlates with a method's stability-plasticity trade-off. Rewarding behavioral diversity in a GA through novelty search makes the population even more plastic, at the cost of forgetting. Finally, symptoms of plasticity loss commonly reported in RL do not transfer to NE. Overall, these results establish NE as a competitive alternative to RL under continual task changes, and suggest that training under perturbations in weight space may be a useful mechanism for continual learning more broadly.
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cs.CRcs.AIcs.LG Emmanuela Andam, Rana Shaaban, Emanuel Grant et al. · Oct 1, 2026

This paper addresses multi-class ransomware family classification by repurposing the Structured State Space Sequence (S4) model—designed for natural sequences—on static PE metadata. The authors reshape 71 tabular features into pseudo-sequences of length 32 and jointly train for binary detection and family classification, claiming S4 captures long-range dependencies in malware execution flow. They benchmark against CNN, LSTM, GRU, Transformer, and MLP baselines on the Ransomware Dataset 2024, reporting strong aggregate F1-scores. However, the study is limited to a single public dataset and single-run metrics, so its broader validity for IoT security remains unproven.

By 2030, Internet of Things (IoT) devices are projected to reach 40 billion, with fast-paced technological advancements in fields such as industry, healthcare, agriculture, automobiles, and building/home automation systems. This expansion has created a large attack surface for cybercrime, as the majority of these devices open the door for cybercriminals to exploit vulnerabilities, as they lack adequate built-in security. Cybercriminals launch malware attacks to compromise systems or steal sensitive data, and once a system is compromised, a ransom is typically demanded for its release. Current cybersecurity measures in place are being outpaced by the rapid growth of the IoT, which is accompanied by a subsequent growth in malware variants being created per day. Recognizing this pitfall, this research examines and proposes a novel approach to malware detection and classification to safeguard devices from further attacks and make IoT systems more robust and secure. The framework proposed utilizes a Structured State Space Sequence (S4) model, which discretizes sequences of malware samples in a sequence and captures long-range dependencies, essentially identifying the "cause" and "effect" hidden within malware execution flow. This study presents two novel contributions: the first empirical application of the S4 model for malware analysis, and a comprehensive comparison of its performance against other deep learning architectures, laying the stepping stone for future research in this new paradigm.
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cs.LGcs.AI Loys Masquelier, Etienne Le Naour · Oct 1, 2026

Spatial climate downscaling aims to recover fine-grained meteorological fields from coarse-resolution inputs, but standard pixel-level metrics such as MAE can hide critical failures in variability or spatial structure. This paper benchmarks five downscaling methods—from a residual U-Net to optimal-transport and contrastive-retrieval approaches—using five complementary criteria that disentangle pointwise accuracy, spectral fidelity, spatial alignment, distribution match, and gradient sharpness. The central finding is that no single method dominates across all measures, and method rankings systematically reverse depending on whether the evaluator rewards smooth alignment or realistic fine-scale variability. This motivates the core message: robust climate downscaling assessment must be explicitly multi-metric and application-aware.

Climate downscaling aims to reconstruct fine scale spatial fields from coarse resolution inputs. Evaluating the quality of these reconstructions is challenging: low pointwise error can come at the cost of fine scale variability, while realistic spatial variability can be achieved with inaccurate local structures. The evaluation metric can therefore change which method appears to perform best. This work presents a multi metric benchmark comparing five spatial downscaling methods on ERA5 temperature, wind, and precipitation fields. Five criteria assess complementary properties: pointwise error, structural similarity, distribution error, spectral error, and gradient error. The results reveal a systematic trade off between spatial fidelity and fine scale variability. Some methods perform best on pointwise and spatially aligned metrics, but lose high frequency content, while others preserve substantially more spectral variability at the cost of less accurately positioned local structures. Consequently, method rankings change across metrics and variables. These results show that there is no single best downscaling method. Multi metric evaluation is therefore essential for assessing which properties of a climate field are preserved.
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cs.CRcs.LG Alessandro Pegoraro, Daryan Merx, Phillip Rieger et al. · Oct 1, 2026

LLMLeak demonstrates a covert channel where malware on a network-restricted device embeds secrets into URLs within fake error messages. When users paste these traces into LLM coding assistants, the model's legitimate web-fetching tool exfiltrates the secret via DNS or HTTP requests to attacker-controlled servers. The work challenges the assumption that local LLM deployment or prompt-injection defenses alone prevent data leakage to third parties.

With the increasing capabilities of Large-Language-Models (LLMs) and LLM-based agents, users are increasingly using them to solve everyday problems, such as answering e-mails or providing programming support. Existing work has extensively investigated security and privacy risks, such as prompt injections and the disclosure of sensitive data to chatbot providers. While various solutions were developed to address these risks, including input structuring to prevent prompt injections or deploying local LLMs to avoid sharing confidential data with chatbot operators, LLMs also pose the risk of leaking confidential data to third parties. In this paper, we demonstrate with LLMLeak a novel attack vector where malicious software that runs locally but cannot communicate directly with the internet abuses LLMs to establish a covert channel. While inputs that instruct the LLM to send data directly via generated code are easy to detect and network libraries are typically restricted, LLMLeak relies only on the LLM's tool to fetch websites for further information. A malicious software component on the client side embeds a secret into a URL. It presents the referenced website as providing information required for a benign task, such as migrating a software library. When the LLM accesses the URL, the attacker receives the encoded secret through an attacker-controlled DNS or web server. We perform an extensive evaluation on eleven open-parameter models, observe an attack success rate of 79.7%, and also conduct a case study on real-world chatbots, demonstrating the relevance of LLMLeak.
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cs.LGcs.AI Feiyu Gavin Zhu, Xiaoyu Zhu, Jiqi Yang et al. · Oct 1, 2026

Multimodal search agents traditionally interleave observations, freeform reasoning, and actions, but small models often waste inference budget generating lengthy reasoning traces that provide little actionable guidance. This paper introduces Selection-based Structured Reasoning (SSR), which replaces open-ended reasoning generation with a discrete selection among a small set of reusable natural-language reasoning candidates. By scoring all candidates in parallel via teacher-forced prefill with a shared KV cache, SSR cuts per-turn reasoning latency by over 90% while maintaining competitive task performance across seven benchmarks with 2B and 4B models.

Multimodal agents commonly generate free-form reasoning before each action. For small models, limited model capacity can result in lengthy reasoning that provides little useful guidance for action generation while incurring substantial inference cost. To address this challenge, we introduce Selection-based Structured Reasoning (SSR), a framework that reformulates reasoning as selection instead of open-ended generation. SSR represents recurring high-level reasoning as pre-specified, reusable natural-language candidates. At each turn, the model selects from these reasoning candidates based on their likelihoods given the current context, without requiring an auxiliary task head. Using pre-specified reasoning traces enables parallel scoring, where teacher-forced prefilling computes token likelihoods concurrently within and across candidates using a shared context KV cache. We evaluate SSR on seven multimodal search benchmarks using 2B and 4B models. Across multiple reinforcement learning objectives and supervised fine-tuning, SSR delivers significant efficiency gains without sacrificing task performance. SSR achieves an average success rate competitive with leading search agents of the same scale, while reducing per-turn reasoning latency by over 90% and total per-question model inference latency by 28-54%. Project page: https://zfy0314.github.io/ssr-webpage/.
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cs.LG Haoyang Jiang, Zhengui Wang, Shenghan Gao et al. · Oct 1, 2026

Open-boundary hydrologic graphs such as river networks and coastal meshes exchange fluxes with unobserved exteriors, making long-horizon forecasting unstable because boundary forcing is unavailable at prediction time. This work proposes PRSOBG, which learns ghost-node proxies to approximate missing external forcing and applies local and global physics refiners to suppress error amplification during autoregressive rollout. Evaluated on the Danube river system and Chesapeake Bay, the framework cuts RMSE by up to 51% over a vanilla STGNN backbone with only about 8% training-time overhead.

Spatiotemporal forecasting on hydrologic graphs is especially prone to instability in open-boundary systems, where the forecast domain exchanges fluxes with an unobserved exterior. In such systems, boundary nodes receive external forcing, e.g., upstream inflows in rivers or tidal signals in coastal regions, that is typically unavailable at prediction time. The absence of this information can compound errors as forecasts unfold in an autoregressive fashion, leading to inferior long-horizon performance. This paper dissects this instability issue by exploring two questions. 1) What boundary forcing enters the forecast domain when information beyond the boundary is missing? 2) How should this forcing propagate through the domain without incurring error amplification under autoregressive rollout? To address both, we propose a new computing framework comprising two key components. First, to compensate for the boundary forcing, our framework learns ghost node proxies from the boundary and interior nodes, striving to approximate unobserved external inputs. Second, to control error accumulation from these learned proxies, we leverage two physics refiners. In particular, one refiner enforces local consistency by aligning ghost proxies with their two-hop neighbors (i.e., boundary nodes and their immediate interiors). The other refiner enhances global stability by correcting the model forecasts through a physics-guided graph neural operator, reducing long-horizon numerical drift. Two real-world hydrologic graphs are employed for empirical evaluation. Comparative results show that our proposal enjoys higher prediction accuracy and long-horizon stability over both learning-based and physics-informed model competitors.
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cs.LG Yifan Guo · Oct 1, 2026

Modern adaptive model development loops propose challengers against a moving incumbent: once a model is adopted, it becomes the reference for future candidates, meaning an unsupported replacement propagates into later hypotheses.

This paper introduces Evidence-Gated Research (EGR), a statistical adoption layer that freezes each challenger before its decision evidence is observed, constructs anytime-valid e-processes across predeclared environments under predictable routing, composes a persistent candidate e-value via an intersection–union minimum, and passes it to an online FDR controller.

The framework matters because it formally separates flexible proposal generation from the validity of state-changing adoptions and empirically demonstrates that naive development-only or single-environment validation can incur massive persistent false-discovery rates in closed-loop search.

Adaptive model search is path dependent: once a challenger is adopted, it becomes the reference from which later candidates are generated. A statistically unsupported replacement can therefore alter hypotheses that have not yet been proposed. We introduce Evidence-Gated Research (EGR), a statistical adoption layer for moving-incumbent search. EGR freezes each challenger before decision evidence is revealed, builds anytime-valid evidence across a predeclared set of environments, routes evidence predictably toward unresolved components, composes a persistent candidate e-value, and passes that e-value to an online controller. Under explicit conditional-validity and predictability conditions, the resulting procedure controls false discovery rate for the declared all-environment adoption target even though earlier adoptions change later challengers. In a 5,000-trajectory closed-loop benchmark, development-only e-LOND attains persistent FDR 0.621, whereas no persistent false-adoption path is observed for the audited EGR variants in that finite run. In matched replay over 600 challenger--incumbent pairs, Stagewise EGR preserves fixed-anytime alternative crossing decisions while using 56.1% less decision evidence at the representative threshold. A three-environment public-data study and a 40,000-sample controlled neural benchmark reproduce the evidence-efficiency pattern. These results identify model replacement as a distinct statistical control point in adaptive model development.
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cs.CYcs.HCcs.LG Hitoshi Inoue, Koichi Yasutake · Oct 1, 2026

This paper confronts the design problem of building dashboards for novel computational techniques whose real-world meaning is still contested. It introduces TopoLA, a system applying Zigzag Persistent Homology to learning-management data, and derives three principles for managing interpretive uncertainty: separating measurement from interpretation, graduated disclosure, and explicit acknowledgment of methodological limits. The argument is timely because fields from explainable AI to bioinformatics increasingly face the same gap between analytical power and interpretive consensus.

Topological Data Analysis (TDA) offers novel methods for understanding temporal dynamics in complex systems, yet its application in information systems design faces a fundamental challenge: how should systems present analytical outputs when interpretation frameworks are still developing? This paper reports on the development of TopoLA, a dashboard system applying Zigzag Persistent Homology to learning management system data, and proposes three early design principles for interpretation support in emerging analytics: (1) separation of objective measurement from contextual interpretation, (2) graduated disclosure from metrics through patterns to reflective prompts, and (3) explicit acknowledgment of methodological uncertainty. The system implements a modular three-stage pipeline--feature extraction, topological computation, and interpretation support--enabling extension to additional analytical methods. This work contributes to information systems research by articulating preliminary design knowledge for systems that must communicate analytical insights from methods lacking established interpretation norms--a challenge increasingly common as novel computational techniques enter applied domains.
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cs.ROcs.CVcs.LG Kartik B. Kapse · Oct 1, 2026

Autonomous driving system designers face a persistent dilemma: should they build a decomposed modular pipeline or train an end-to-end neural policy? This survey-style paper addresses that question by comparing modular, imitation-learning, reinforcement-learning, and hybrid architectures across interpretability, scalability, and robustness. Its central contribution is a practical twelve-criterion, four-dimensional framework intended to guide practitioners in selecting the right paradigm for a given deployment context.

Autonomous driving systems have become a central focus of intelligent transportation research, with End-to-End Learning and Modular Architectures offering two prominent design paradigms for their implementation. E2E Learning uses deep learning algorithms to map raw sensory inputs directly to driving actuators, providing a streamlined and adaptable solution. while Modular Architectures employ a pipeline-based approach, dividing the system into distinct subsystems for perception, cognition, planning, and control. This paper presents a comprehensive comparative analysis of these paradigms, focusing on their strengths, limitations, and trade-offs to provide insights into their suitability for various autonomous driving applications. The study evaluates key factors such as interpretability, scalability, robustness, and real-world applicability. While End-to-End Learning emphasizes simplicity and adaptability in dynamic environments, it lacks transparency and is highly dependent on large datasets. Conversely, Modular Architectures offer superior interpretability and task-specific optimization, but face challenges related to integration complexity and scalability. To address these limitations, hybrid approaches that combine the strengths of both paradigms have emerged, offering a promising direction for overcoming these challenges. Beyond this comparative synthesis, following work proposes a Four-Dimensional Architecture Selection Framework, comprising twelve binary criteria across safety, operating environment, data/computational resources, and deployment context, and validate it against ten published autonomous driving systems, correctly recommending 7/10 deployed architectures. This work synthesizes existing literature to highlight key trade-offs between the paradigms and identifies hybrid architectures as a promising direction for future research.
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cs.ROcs.AIcs.LG Seungyeon Kim, Junhoo Lee, Baekseung Kim et al. · Oct 1, 2026

World Action Models (WAMs) jointly predict visual futures and robot actions, yet they often hallucinate locally plausible trajectories that never execute the critical state transition needed to finish the task. This paper identifies "task-incomplete imagination" as a failure mode arising from the mismatch between long-horizon video pretraining and short-horizon control generation, and proposes Completion Aware Guidance (CAG), a training-free sampling method that up-weights instruction tokens already attended to by the model. Across two WAM architectures, CAG boosts success rates and cuts incomplete-imagination failures, offering a lightweight inference-time fix for a structural objective mismatch.

World Action Models (WAMs) predict visual futures and robot actions, yet they remain susceptible to task-incomplete imagination, where plausible, action-consistent predictions omit the transition needed for task completion. In this paper, we show that this failure is not inherent to the world model backbone, but emerges when adapted for short-chunk control, which can repeatedly favor plausible local continuations over task-completing transitions. To address this, we introduce Completion Aware Guidance (CAG), a training-free sampling method that guides generation toward task completion. Across representative WAMs, CAG improves success from 64% to 70% on a RoboTwin 2.0 subset and from 69% to 75% in zero-shot simulation, while reducing task-incomplete imagination from 79% to 40%.
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cs.LG Jiajun He, Denis Blessing, Mouyang Cheng et al. · Oct 1, 2026

Sampling from discrete, unnormalized distributions without curated data is a fundamental bottleneck in physics, chemistry, and combinatorics, because the state space is exponential and Markov chains mix too slowly. This paper introduces DIG-IN (Discrete Gibbs Iterative Neural Sampler), which trains masked diffusion models via fixed-point iteration by using Gibbs soft labels—local single-site conditionals derived from energy differences—as rich supervision instead of one-hot reconstruction targets. The method tempers importance weights by effective sample size to stabilize the bootstrap, and it scales to high-dimensional systems such as $D=2500$ lattice spin models and alloy phase diagrams.

Sampling from discrete, unnormalized distributions without access to data is a challenging problem. Neural samplers offer a promising approach by training generative models from density evaluations directly. Despite recent progress, existing discrete neural samplers are prone to mode collapse, come without convergence guarantees when trained via fixed-point iterations, and are often tied to a specific reference process such as masked or uniform diffusion. In this work, we introduce Discrete Gibbs Iterative Neural Sampler, a fixed-point neural sampler that addresses these limitations, enabling efficient, scalable learning, substantially reducing mode collapse in practice. Our framework builds on masked diffusion and also extends to transport between pairs of distributions. We demonstrate that the resulting method scales effectively to high-dimensional systems, supports amortized sampling across different conditions, and enables accurate estimation of alloy phase diagrams.
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cs.CYcs.LG Hitoshi Inoue, Koichi Yasutake · Oct 1, 2026

Asynchronous online learning structurally fragments learner communities, and cohort-level topological indicators like $\beta_0$ can misleadingly suggest convergence when learners simply drop out. This paper tests whether $\beta_0$ from Zigzag Persistent Homology is participation-sensitive and whether deadline-driven fragmentation–convergence cycles replicate across all 22 OULAD courses. Clarifying this matters because AI-augmented dashboards risk spreading systematically misleading cohesion narratives if they misread attrition-driven $\beta_0$ declines.

Asynchronous online learning offers temporal flexibility at a structural cost: learning communities tend to fragment rather than cohere. $\beta_0$, the number of disconnected behavioral clusters from Zigzag Persistent Homology, serves as a cohort-level indicator of this structure. Two questions remained unverified at scale: (1) does apparent $\beta_0$ convergence reflect genuine behavioral alignment or learner dropout? and (2) do assessment deadlines produce reproducible fragmentation-convergence cycles? We address both across all 22 OULAD courses (N > 22,000; 857 week-pairs). Changes in $\beta_0$ strongly co-vary with active learner changes (pooled r = 0.387; median per-course r_delta = 0.459, 20/22 courses), identifying $\beta_0$ as a participation-sensitive indicator: $\beta_0$ and active learner counts co-respond to deadline events rather than one causing the other. Deadlines produced fragmentation in 82.6% of assessments and the full Fragment First, Converge Later (FFCL) cycle in 60.2%. 3-phase analysis confirmed structural fragmentation as the dominant long-term trajectory (90.9% of courses), moderated by curriculum structure. These findings establish $\beta_0$ as a participation-sensitive structural indicator with direct implications for AI-augmented learning analytics design.
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cs.LGcs.RO Takumi Hara, Kanata Suzuki · Oct 1, 2026

Latent world models plan by scoring action sequences with latent-space distances, yet physical success criteria demand precision finer than these models typically encode. This work proposes a training-only auxiliary loss that supervises encoder and predictor outputs against the exact success-criterion quantities via a shared linear head, then discards the head at test time so planning remains unchanged. On manipulation tasks the approach yields statistically significant absolute gains of 3-5%, with the key insight that a task's success criterion itself should dictate what the latent state must retain.

Latent world models plan by scoring candidate action sequences with distances in latent space. However, task success is judged by physical quantities, which we call the success-criterion quantities. In all four latent world models we examine, the end-effector position is encoded in the latent state with an error larger than the success criterion allows. Such a latent state cannot separate successful candidates from failing ones. We propose an auxiliary loss that uses success-criterion quantities as training targets, whereas existing latent world models take them only as inputs. During training, a linear head on the encoder and predictor outputs regresses the success-criterion quantities, and the regression error is added to the training loss. The head is discarded after training, so the model, its cost, and its inputs at test time are unchanged. This loss alone improves the success rate on PushT and cube by 3.5% and 3.4% (absolute), respectively, and both improvements are statistically significant. A success criterion thus specifies what a world model must retain in its latent state, and we show that it can serve directly as a training target.
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cs.LGcond-mat.dis-nnstat.ML Haotian Gu, Yizhou Xu, Lenka Zdeborov\'a · Oct 1, 2026

This paper studies nonlinear in-context learning via single-index models, comparing a kernel learner (fixed spherical-harmonic features followed by linear attention) against a feature learner (linear attention on raw inputs followed by a learned nonlinear readout). Using the replica method, the authors derive predictions for memorization and generalization errors across varying pretraining data, task diversity, and context lengths, and validate them numerically over a broad parameter range. The analysis reveals phase diagrams for architectural advantage and qualitatively different context-length scalings: the kernel learner needs $L = \Theta(d^k)$ to recover degree-$k$ harmonics, while the feature learner exploits all teacher components at $L = \Theta(d)$.

In-context learning (ICL) enables a pretrained model to infer a task from demonstrations without updating its parameters. While much of the existing theory focuses on linear target functions, in this paper we study nonlinear cases by comparing two one-layer attention architectures on the same family of single-index tasks. A kernel learner first maps inputs through a fixed nonlinear feature map and then applies linear attention, whereas a feature learner applies attention to the original input, followed by a learned nonlinear readout. We derive predictions for their memorization and generalization errors using the replica method, retaining the effects of pretraining size, task-pool diversity, and training and inference context lengths. The resulting predictions closely match numerical experiments across a broad range of regimes. Our analysis yields phase diagrams that characterize when each architecture is advantageous as the amount of pretraining data, task diversity, and context lengths vary. We further identify qualitatively different context-length scalings for the two learners. Together, these results clarify how architectural choices interact with the dataset and govern nonlinear in-context learning.
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cs.LG Zihan Liu, Xurong Xie · Oct 1, 2026

This work tackles algorithmic mathematical reasoning, where final-answer rewards fail to expose intermediate errors and successful code execution does not guarantee correctness. The proposed Function-Structured Graph Reinforcement Learning (FSG-RL) framework connects typed subproblem graphs to executable Python nodes, then trains a policy with supervised fine-tuning followed by Group Relative Policy Optimization (GRPO) using multi-verifier rewards and span-level credit assignment. The core claim is that verifying interface compliance, local functional behavior, and final consistency together pushes a 9B parameter model past a 27B API baseline, while also providing statistically significant gains over a strong SFT stage.

Algorithmic mathematical reasoning requires reliable decomposition, computation, and aggregation. Final-answer rewards provide limited guidance on intermediate errors, while successful execution does not guarantee mathematical correctness. This work proposes Function-Structured Graph Reinforcement Learning (FSG-RL), connecting subproblem graphs and Python implementations with multi-verifier feedback. The policy first learns to generate code from function graphs through supervised fine-tuning (SFT). Group Relative Policy Optimization (GRPO) then optimizes the policy using answer-gated rewards and span-level credit assignment. The framework also supports teacher supervision and structured memory. A benchmark curated from Grade School Math 8K (GSM8K), MathQA, MATH, and Omni-MATH pairs public function graphs with private verification specifications. Under a unified evaluation protocol, GRPO improves final-answer accuracy from 43.25% to 67.50% and full solution success from 32.25% to 52.25% over SFT. Continued reinforcement learning (RL) with teacher supervision yields additional gains. The gains extend beyond producing correctly formatted code, supporting verifier-guided reinforcement learning for mathematical reasoning. Code is available at https://github.com/ZihanLiummyycc/FSG-RL.
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cs.LGcs.AI David Berghaus · Oct 1, 2026

Instead of hand-designing or training a neural network for time-series anomaly detection, this paper outsources the job to an LLM-driven autonomous research loop. The agent iteratively edits a short NumPy program, scoring candidates against synthetic anomalies in a held-out training slice, until it discovers compact spectral-Gaussian novelty detectors. The resulting univariate and multivariate programs reportedly top the TSB-AD benchmark while running on a single CPU, offering an unusual blend of accuracy, speed, and interpretability.

Time-series anomaly detection trades off predictive accuracy, computational efficiency, and interpretability. We use a large language model not as the detector but as the author of one: an autonomous research loop in which the model repeatedly edits a single short NumPy program under a leakage-free objective, keeping the best-scoring detector it finds. The loop discovers two compact detectors, one for univariate and one for multivariate series, that describe short windows by their local spectral features and compare them with the training-region distribution through a covariance-aware distance. On the TSB-AD benchmark these detectors lead the field across metrics, ahead of the strongest classical, deep, and foundation-model baselines including Time-RCD, yet they train no network and use no GPU, and the multivariate detector is faster than every similarly performing baseline. LLM-driven program search is thus a practical route to accurate, efficient, and transparent detectors.
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cs.LGcs.CL Ivan Ilin, Peter Richt\'arik · Oct 1, 2026

QK-Wanda attacks a blind spot in activation-aware LLM pruning: Wanda scores query and key weights independently even though their dot products jointly determine attention. The paper derives closed-form single-deletion costs under a coupled QK reconstruction objective, letting queries and keys share a pruning budget without gradients or weight updates. Across 15 models up to 72B parameters, the method cuts local QK reconstruction error by roughly half, yet downstream gains are uneven—Llama 2 and Qwen2.5 improve while Llama 3 degrades—highlighting that local reconstruction fidelity is an imperfect proxy for end-to-end model quality.

Wanda (Sun et al., 2024) prunes large language models by scoring weights independently within each linear projection, although queries and keys interact through dot products. We introduce QK-Wanda, which scores query and key weights by their individual deletion costs under an unmasked pre-RoPE reconstruction objective. It augments Wanda scores with information from the opposite projection (keys for query weights, and queries for key weights), allowing both projections to share a pruning budget. Its closed-form scores require no gradients or weight updates; full pruning takes 1.3% longer than Wanda on A100 and 3.1% longer on H200 with the calibration used in our main experiments. We evaluate QK-only pruning across 15 models from TinyLlama, Llama 2, Llama 3, and Qwen2.5, spanning 0.5B-72B parameters. Relative to Wanda, QK-Wanda reduces QK reconstruction error by an average of 60% at 50% sparsity and 45% at 80%. Downstream gains depend on the model. At 80% sparsity on Llama 2 70B, WikiText-2 and C4 perplexity decrease by 20.3% and 13.5%, while mean zero-shot accuracy rises by 5.94 percentage points. Qwen2.5-72B also improves, but Llama-3.1-70B has substantially higher perplexity despite lower reconstruction error. These results show both the promise of coupled pruning criteria and the limits of local reconstruction as a predictor of model quality.