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cs.LG Zinan Ling, Yang Xiao, Ruimeng Ye et al. · Oct 14, 2026

LLM unlearning is usually tested by whether a model refuses harmful queries and retains clean-task accuracy. The authors highlight a gap: models can pass those checks while failing when benign prompts sit just outside the forgotten domain, a failure they term forget-adjacent utility loss. They propose RA2, which redirects forget-token hidden states toward nearby retain-supported anchors instead of simply pushing them away. Experiments on WMDP and MUSE show this directional choice meaningfully reduces neighborhood-level collateral damage.

Large Language Model (LLM) unlearning is often evaluated primarily by target suppression and clean retain utility. These metrics can miss a local failure mode: a model may perform well on standard retain prompts, yet degrade on benign reasoning when prompts lie near the forgotten domain. This phenomenon is termed forget-adjacent utility loss. A fundamental question is: where should forget representations go after they leave the removed behavior? Successful unlearning depends not only on whether forget-conditioned representations depart from the harmful computation, but also on the direction in which they are redirected afterward. We propose RA$^2$ (Retain-Anchored Attraction), a latent-space unlearning method that redirects forget-token states toward nearby retain-supported representations while preserving higher-layer behavior on retain data. On WMDP and MUSE, RA$^2$ yields higher forget-adjacent utility than strong unlearning baselines at similar broad-utility levels. These results show that the migration direction of forget representations materially affects benign behavior near the forget boundary. Our code is available at https://github.com/ZacLing/retain_anchored_attraction.
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cs.ROcs.AIcs.LG Huixuan Cheng, Bike Zhang, Shankar Sastry et al. · Oct 14, 2026

This paper investigates whether high-performing humanoid control networks can be synthesized directly in weight space rather than trained conventionally. The authors adopt a latent diffusion framework---pairing a cluster-wise linear autoencoder with a Diffusion Transformer---to generate weights for 3-layer MLP policies on a Unitree G1 robot, achieving zero-shot sim-to-real transfer for walking, dancing, and spin kick. Alongside generation, they analyze the learned weights and identify a kinematic prior in first-layer parameters that emerges under both reinforcement and imitation learning, suggesting embodiment-specific structure in policy weights.

Recent advances in robot learning have driven rapid progress in humanoid control, enabling increasingly agile behaviors in the real world. However, humanoid control networks are typically obtained through conventional training procedures, while comparatively little attention has been given to directly modeling the distribution of their learned weights and generating functional networks in weight space. In this work, we investigate whether high-performing humanoid control networks can be generatively modeled directly through their weights. We adopt a latent diffusion framework that couples a linear autoencoder with a Diffusion Transformer. The autoencoder compresses actor network parameters into a compact latent space, and the Diffusion Transformer models the distribution of these latents. Trained on networks collected from reinforcement learning for the Unitree G1 robot, our approach generates deployable networks that perform various motions in the real world, including walking, dancing, and spin kick. Beyond generation, we further study the learned weight space to better understand the structure captured by these humanoid control networks. We identify a structural principle in the first-layer weights that consistently reflects the robot's kinematic prior. Notably, this kinematic prior emerges under both Reinforcement Learning (RL) and Imitation Learning (IL) training, suggesting that it is not specific to a particular optimization process but may instead reflect common knowledge associated with humanoid embodiment. Together, these results demonstrate the feasibility of generative modeling in humanoid network weight space, while providing initial insights into the information encoded by their learned weights. Additional results are available on our project website: https://humanoid-weight-diffusion.github.io/
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cs.ITcs.LGmath.IT Zhijie Su, Shiquan Zhang, Qiaolin He · Oct 14, 2026

This paper tackles digital-domain self-interference cancellation in in-band full-duplex radios, where conventional adaptive filters degrade when the desired signal is much stronger than the residual interference.
The authors reformulate cancellation as an operator-learning problem: a Transformer neural operator learns the temporal evolution of the self-interference channel from historical observations and reconstructs the current interference from the known transmit signal.
Trained in a desired-signal-free setting and applied during contaminated reception, the method reduces reliance on corrupted instantaneous updates and reports strong high-SIR stability.

Digital-domain self-interference cancellation is essential in in-band full-duplex radios after passive suppression and analog cancellation. It is particularly challenging when the desired signal is strong relative to the residual self-interference. In this regime, conventional iterative digital cancellers update their coefficients from desired-signal-contaminated received samples and may suffer substantial performance degradation. This paper reformulates digital-domain self-interference cancellation as an operator-learning problem. The proposed framework learns the temporal evolution of the residual self-interference channel from historical observations and uses the learned operator together with the known local transmit signal to reconstruct the current residual self-interference. A Transformer neural operator is used to realize this framework. The resulting method is trained in a desired-signal-free setting and then applied in the presence of a desired signal. A continuity-based analysis characterizes the sensitivity of the learned operator to the resulting input perturbation. Numerical experiments in static and time-varying channels, including time-varying SIR conditions, demonstrate stable cancellation performance over a wide range of interference levels. At 30 dB SIR, the proposed method improves the cancellation performance by 5--15 dB over the considered conventional methods.
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cs.LG Giorgio Morales, Anik\'o Ek\'art · Oct 14, 2026

Neural symbolic regression models are bottlenecked by training datasets riddled with structural redundancy and simplicity bias. This paper proposes ExCaUS, a deterministic grammar-based framework that exhaustively enumerates canonical univariate skeletons under explicit unary-count and depth bounds, eliminating duplicate functional forms. The authors pair this with a derivative-driven sampling strategy and a 150-problem benchmark, demonstrating that curated structural diversity exposes severe weaknesses in state-of-the-art SR methods.

Neural symbolic regression (SR) models require diverse datasets of mathematical expressions for robust training. However, existing datasets rely predominantly on stochastic sampling methods, which suffer from high structural redundancy and incomplete functional coverage. To address this, we introduce an exhaustive dataset of univariate canonical skeletons generated via a deterministic constrained context-free grammar. A canonical skeleton acts as a generic structural representation that subsumes more specific functional forms, eliminating redundant expressions and avoiding repeated computational efforts. Although our dataset consists of univariate skeletons, it is designed to support the decomposable SR paradigm to solve multivariate SR problems without assuming linear separability. Furthermore, we pair this dataset with a sampling strategy that generates clean numerical data without triggering numerical instabilities or relying on artificial protected operators. Canonicalizing two existing neural SR datasets reveals that our dataset is substantially more compact, eliminates structural repetitions, and achieves a uniform operator distribution free of simplicity bias. Finally, we establish a benchmark of 150 SR problems across three tiers, on which state-of-the-art SR methods are shown to struggle significantly.
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cs.LG Maria V. Salvador, Ana F. Sequeira, Jaime S. Cardoso · Oct 14, 2026

The paper investigates when jointly optimizing imputation with a downstream classifier improves robustness under train–test mismatches in missingness rates or mechanisms. Instead of treating imputation as fixed preprocessing, the authors cast missing values as learnable variables regularized around a reference imputation, giving both amortized and latent instantiations. Through 98 tabular classification datasets—and targeted shift experiments on 36 datasets—they show that reconstruction quality is a poor proxy for predictive utility and that task-aware corrections matter most in hard regimes such as MNAR and severe distribution shift.

Missing data is a pervasive challenge in machine learning, often degrading predictive performance and complicating model deployment. Most existing approaches treat imputation as a preprocessing step independent of the downstream task, a separation that becomes problematic under train-test mismatches in missingness mechanisms or rates. We introduce a unified framework that treats missing entries as variables in a task-conditioned optimization problem. We instantiate this framework in two settings: an amortized approach for scenarios with missing data at both training and test time, and a latent optimization approach for settings where only training data is incomplete. The evaluation is conducted on 98 tabular datasets, and robustness under train-test mismatches is assessed on 36 datasets. Results reveal that reconstruction error constitutes a poor proxy for predictive utility (Spearman rho approximately 0.16 to 0.32), and that task-aware imputation becomes critical in scenarios where classical methods fail to recover complete-data performance, achieving win rates of up to 80% in challenging train-test mismatch scenarios.
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cs.CGcs.CCcs.LG Ditbul Ban, Younghun Roh, Julian Shun et al. · Oct 14, 2026

Most standard diversity measures violate at least one of the Mironov–Prokhorenkova axioms (monotonicity, uniqueness, continuity), and the only known measures that satisfy all three are NP-hard to compute. This paper introduces Geometric Kernel Diversity (GKD), which defines diversity as the volume of the union of radial-kernel under-graph solids for a point set in Euclidean space. For a canonical Student-$t_2$ kernel, the authors prove that GKD satisfies all three axioms on Euclidean-realizable inputs, give exact polynomial-time algorithms for dimensions $d \leq 3$, and provide a randomized $(1\pm\varepsilon)$-approximation for arbitrary dimensions. The contribution is a theoretically clean first positive answer in the restricted Euclidean setting, though the axiomatic question on general distance matrices and exact computation in $d \geq 4$ remain open.

Quantifying the diversity of a set of objects is a fundamental problem in machine learning and statistics. Mironov and Prokhorenkova (2025) recently showed that three axioms-monotonicity, uniqueness, and continuity-are crucial for a reliable diversity measure and that none of the standard metrics in the literature satisfy all three. They also constructed two measures that do satisfy the axioms, but both are NP-hard to compute, leaving open the question of whether efficient axiomatic diversity measures can exist. We study a Euclidean-restricted version of this question. We introduce Geometric Kernel Diversity (GKD), which associates a radial kernel solid with each point and measures the volume of their union. We show that canonical GKD satisfies all three Mironov-Prokhorenkova axioms on Euclidean-realizable inputs. For canonical GKD, we give exact polynomial-time algorithms in dimensions $d \le 3$. In arbitrary dimensions, we give a randomized algorithm that returns a $(1 \pm \varepsilon)$-approximation with probability at least $1-\delta$ in time $O \left(\frac{nd}{\varepsilon^2}\log\frac{2}{\delta}\right)$ for $n$ points. The axiomatic guarantee applies to exact canonical GKD; the randomized algorithm approximates this deterministic quantity. We further show that the two diversity measures of Mironov and Prokhorenkova (2025) remain NP-hard on Euclidean-realizable inputs and, unless $\mathrm{NP} = \mathrm{RP}$, admit no FPRAS even on this restricted domain.
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cs.LGstat.ML Dai Shi, Andi Han, Xiaoyu Li et al. · Oct 14, 2026

Conflicting studies on whether neural networks converge to a shared representation have used different alignment metrics and reached opposite conclusions. This paper proposes the Lattice Representation Hypothesis (LRH), which formalizes alignment criteria into a lattice ordered by strength, and argues that disagreements arise because prior work evaluates criteria at different points on this lattice. It also proves in idealized models that the training procedure and objective determine which criteria are met reliably across independent runs, supported by experiments on dozens of pretrained vision and language models.

The Platonic Representation Hypothesis (PRH) holds that increasingly capable models converge toward a common representation. However, recent studies have shown different views on aligning representations via their neighborhoods, spanning trees, and distances. We show that these views can differ because the alignment criteria behind them sit at different points of one lattice, and we formalize this explanation as the Lattice Representation Hypothesis (LRH). Under the LRH, the convergence claimed by the PRH is agreement at the top of the lattice, whereas its evidence comes from neighbor overlap, a criterion near the bottom. The Aristotelian Representation Hypothesis (ARH) restricts convergence to local neighborhoods because calibration keeps the growth of neighbor overlap with model size but largely removes that of centered kernel alignment. We show that this removal can come from calibrating a maximum over layers, so global convergence remains open. Back into Plato's Cave (BPC) infers coarse shared structure from the collapse of neighbor overlap on larger evaluation sets, whereas we trace it at least partly to a fixed number of neighbors covering shorter distances. We show that the spanning-tree overlap used by Structure over Geometry (SOG) mostly repeats one-nearest-neighbor overlap. The LRH also extends to independently trained models, whose training procedure and objective decide the criteria met reliably across runs. We prove this claim for the training procedure in a linear autoencoder and for the objective in a finite contrastive Gibbs model. Experiments on dozens of pretrained vision and language models and thousands of runs of both theoretical models support these conclusions. We hope this work paves the way toward a general theory of representation hypotheses, with a framework to analyze them and compare their evidence. Project page: https://eethanshi.github.io/LRH
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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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stat.MLcs.LG Haowei Wang, Yilin Zheng · Oct 14, 2026

This paper studies noiseless efficient global optimization via Gaussian Process Thompson Sampling (GP-TS) in the frequentist RKHS setting. It proves that standard GP-TS suffers an intrinsic $\sqrt{\log N}$ simple-regret penalty for Mat\'ern kernels, yielding $O(N^{-\nu/d}\sqrt{\log N})$, and proposes Capped Thompson Sampling (GP-CTS), which achieves the minimax-optimal $\Theta(N^{-\nu/d})$ rate using a known RKHS norm bound. The analysis covers both discrete and continuous domains and is notable for matching upper and lower bounds in a non-bandit setting.

Efficient global optimization aims to identify a global optimum of an expensive black-box function within a limited evaluation budget $N$. We investigate the convergence rates of Gaussian process Thompson sampling (GP-TS) under noiseless observations, assuming a fixed objective function in a reproducing kernel Hilbert space (RKHS). For Mat\'ern kernels with smoothness parameter $\nu$ in dimension $d$, we establish a worst-case expected simple-regret upper bound of $O(N^{-\nu/d}\sqrt{\log N})$ for both discrete GP-TS on sufficiently fine grids and its continuous counterpart. For the continuous implementation, we develop a nested-grid argument to control posterior sample paths over the entire domain. We further establish matching lower bounds of $\Omega(N^{-5/2}\sqrt{\log N})$ for both implementations under a fixed one-dimensional Mat\'ern-$5/2$ kernel, demonstrating that the logarithmic penalty is intrinsic to standard GP-TS in this setting. Motivated by this limitation, we propose Gaussian Process Capped Thompson Sampling (GP-CTS), which caps posterior sample paths using a valid RKHS norm upper bound while preserving optimism. This modification successfully eliminates the logarithmic penalty and achieves the minimax-optimal rate $\Theta(N^{-\nu/d})$ for both discrete and continuous implementations.
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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 "teacher-surpassing" effect. These results establish RM-OPD as a promising paradigm for building generalist GRMs.
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cs.LG Fernando Acero · Oct 14, 2026

Autoregressive transformers trained on limit order book streams are usually evaluated only by output realism, leaving their internal mechanics opaque. This paper inverts the problem by training GPT-style models on synthetic order-flow simulators with known latent parameters, enabling exact verification against Bayes-optimal predictors and oracle entropy floors. It finds that next-token pretraining implements amortized Bayesian inference and online filtering, that latent states are linearly decodable from frozen activations, and that regime diversity—not model scale or token count—drives generalization.

Autoregressive transformers trained on limit order book (LOB) message streams are increasingly proposed as foundation models for market microstructure. Because the generative process of real markets is unknown, these models can be judged only by the realism of their output, leaving open what they actually learn. We make the question answerable by inverting the setup: we train GPT-style models on order flow from simulators whose latent parameters are known, so that the Bayes-optimal predictor, the generating state, and the exact data entropy serve as references. Measured against them, next-token pretraining on order flow implements amortized Bayesian inference over market regimes. The learned predictive matches the exact Bayes optimum to within a millinat per token and approaches the oracle floor even on a nonstationary family whose latent state drifts within an episode, a regime that requires filtering. The latent regime is linearly decodable from frozen activations, well above baselines, so a frozen-model read-out calibrates simulator parameters more accurately than windowed maximum likelihood at a fraction of the cost. In our experiments these capabilities are not produced by scale: capacity and token volume saturate early, and it is the diversity of training regimes, not the token count, that determines generalization to unseen markets. On real NASDAQ data, zero-shot transfer is set by how well the simulator prior covers real flow: an enriched mixture nearly closes the gap to an in-domain baseline, and pretraining beats from-scratch training at every budget across held-out tickers. Known ground truth turns average next-token loss, which is uninformative near the entropy floor, into an exact comparison against the Bayes-optimal and oracle predictors.
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cs.LGcs.CV Miko{\l}aj Pi\'orczy\'nski, Wojciech Masarczyk, Damian S\'ojka et al. · Oct 14, 2026

Multimodal large language models suffer large accuracy drops when their visual inputs are corrupted by noise, blur, or weather artifacts. This paper asks whether test-time feature alignment—matching activation statistics to clean source moments, a technique that works well for CLIP-like classifiers—can recover that lost performance without labels or weight updates. Across three modern MLLMs and 15 standard corruptions, the authors find it cannot: sample-blind, position-shared corrections recover only about one percentage point of an order-of-magnitude larger drop. The core insight is that corruption shifts in MLLM visual token sequences are nearly orthogonal across images and dominate the residual term in a per-token squared-shift decomposition, whereas pooled classification embeddings exhibit a shared, low-rank shift direction. This matters because it establishes that robustness in generative MLLMs is a per-token restoration problem, not a simple domain-statistics-matching problem.

Vision-language models suffer significant accuracy drops under common corruptions. While test-time adaptation (TTA) successfully mitigates these shifts in CLIP-like contrastive models, its application to generative multimodal large language models (MLLMs) remains underexplored and uniquely challenging due to their sequential token generation. In this work, we demonstrate that representation-based TTA fails to recover performance in MLLMs. Our experiments reveal that even when violating standard TTA assumptions by leveraging target data offline, sample-blind feature alignment recovers only marginal accuracy. We attribute this failure to the nature of corruption shifts: unlike CLIP-like architectures, which benefit from a shared domain-shift direction within a single pooled classification embedding, MLLM visual token sequence shifts are nearly orthogonal and span the full embedding space.These findings bound what any sample-blind, position-shared correction at a single encoder site can achieve, establishing that representation-space interventions alone might be insufficient to ensure corruption robustness in MLLMs.
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cs.LG Joshua Cheung, Zhang He · Oct 14, 2026

Latent world models for control are routinely selected and checkpointed by one-step next-embedding prediction loss, on the assumption that lower loss implies better planning. This paper tests that proxy in JEPA architectures by introducing a frozen-decoder protocol that reports one-step error in interpretable physical units, then applies fine-tuning interventions and measures goal-conditioned planning with paired seeds. It finds the relationship saturates after a single epoch within a task and has no stable exchange rate across tasks, implying that latent prediction loss is an unreliable stand-in for planning competence.

Latent world models are routinely selected, checkpointed and ablated on one-step prediction loss, on the assumption that a model which predicts the next latent better is a better model. In model-based RL this assumption is known to be unreliable; we ask whether it also fails for latent world models, where the training target is the model's own embedding and the loss is not expressed in interpretable units. We introduce a frozen-decoder protocol reporting one-step error in physical units, decomposed into the part already present in the encoder's representation and the part the predictor adds. Applying it to a recent end-to-end JEPA world model across three continuous-control environments, we move the metric by fine-tuning and measure goal-conditioned planning on the same checkpoints, with three training seeds and paired planning seeds throughout. Within one environment, a per-epoch ladder shows the relationship saturating after a single epoch: the first epoch improves fidelity by 32% and planning by 4.4 pp, but across the fifteen checkpoints that follow -- a further 15% fidelity improvement, monotone in every training seed -- the correlation between one-step error and planning success is r = -0.010. This is not a task-ceiling artifact: stratifying by a model-independent measure of training-data support, planning in the lowest-support stratum starts at 80%, leaving ample headroom, and is nonetheless flat from epoch 1 onward. Across environments the exchange rate is equally unstable: a 93% fidelity reduction on TwoRoom yields -0.7 pp of planning, while a 40% reduction on PushT yields +4.9 pp [+1.1, +8.9]. All results replicate under a decoder-free measure, latent drift. We also show that a matched continued-training control absorbs the entire fidelity gain we had attributed to an auxiliary objective.
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cs.LG Yuanpu Cao, Saket Sathe, Hanyu Wang et al. · Oct 14, 2026

This paper identifies progress stagnation—unproductive reasoning-action loops—as a critical failure mode when distilling multi-turn agent capabilities from large teachers into small language models via supervised fine-tuning. To mitigate it, the authors propose Progress-Aware Distillation (ProD), which measures the stagnation gap between student-generated and teacher trajectories and encodes that discrepancy into an adaptive margin within a SimPO-style preference objective. The contribution matters because prior agent distillation improves tool-use accuracy yet collapses on longer horizons, directly undermining practical deployment of efficient small-model agents.

While LLM-based agent systems have demonstrated remarkable proficiency in reasoning and solving complex real-world tasks, they also come with substantial token consumption and inference latency, limiting their practical deployment. To enhance the efficiency of agent systems, recent efforts have focused on transferring agentic capabilities from large-scale models to small language models (SLMs) via supervised fine-tuning-based distillation. Nevertheless, as interaction trajectories grow longer, involving extended reasoning-action chains and extensive environmental feedback, distilled student agents tend to experience progress stagnation: becoming trapped in unproductive loops characterized by persistent failed strategies and difficulty making meaningful progress. Our systematic analysis shows that this phenomenon consistently occurs across diverse SLMs and task domains. To address this issue, we propose Progress-Aware Distillation (ProD), which explicitly detects and penalizes stagnation in student-generated trajectories. ProD encodes the stagnation gap between student and teacher into an adaptive margin for dynamically penalizing possible stagnation. By iteratively applying this procedure, ProD enables student agents to progressively approximate teacher behavior. Extensive experiments involving 8 SLMs, ranging from 0.6B to 8B parameters, on both in-domain and out-of-domain benchmarks, demonstrate that ProD substantially mitigates progress stagnation while enhancing both the success rates and task-completion efficiency of distilled SLM agents.
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cs.LGcs.CV Stavros Nousias, Akis Nousias, Konstantinos Gkrispanis · Oct 14, 2026

Steady PDE surrogates on unstructured meshes must resolve multiscale features from a single coarse discretization. This paper proposes routing a mixture of vanilla transformer experts using a learned discrete Hodge-Laplacian controller that measures high-frequency content per vertex. Each expert is biased toward a different spectral scale through auxiliary band targets, and the combined output predicts pressure, velocity, and turbulence fields in one forward pass. On a remeshed AirFRANS benchmark, the architecture cuts mean relative $L_2$ error by roughly a third compared with a Transolver baseline.

Current approaches for steady partial differential equations surrogate models on unstructured meshes apply a single mixing mechanism to the whole solution. This paper proposes an architecture that partitions the solution among vanilla transformer experts, each focused on a different spectral scale. The partition is built from a discrete Hodge Laplacian $L_0=\star_0^{-1} d_0^{\top}\star_1 d_0$, that serves as a fitting layer measuring high-frequency content. A gating mechanism takes the mesh as input and produces the per-vertex weights that recombine the expert outputs. AirFRANS is a steady Reynolds-averaged Navier--Stokes (RANS) airfoil benchmark. We evaluate our approach in a reduced remeshed version of the benchmark with each unstructured mesh counting 9.6K faces and 4.9K vertices. We compare our approach with the Transolver on the same dataset and dataset slit. Our approach reduces relative $L_2$ error by 31\% and interior mean squared error by 47\%.
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cs.LG Robin Uhrich, Marco Bagatella, N\'uria Armengol Urp\'i et al. · Oct 14, 2026

This paper tackles unsupervised pre-training for reinforcement learning: how to learn from reward-free trajectories so that a good policy can be extracted once a task reward is revealed. The core idea is to replace costly, iterative flow-based occupancy models with one-step drifting models, which makes it possible to extract policies by differentiating directly through the generator instead of distilling a separate critic. This matters because it cuts inference cost, removes an entire distillation stage, and improves performance on standard continuous-control benchmarks.

The growing interest in behavior foundation models, combined with recent advancements in generative modeling, has led to an appealing recipe for reinforcement learning from unlabeled data: pre-train a generative model to model occupancies, i.e., discounted state visitations, on reward-free trajectories, such that a policy can be easily extracted once a small reward-labeled dataset becomes available. We decompose this recipe along three axes: (i) the degree to which the multi-modal structure of occupancies must be captured, (ii) the class of generative model, and (iii) the method used for policy extraction. Along each axis, we consider existing choices, propose simpler alternatives, and validate each decision experimentally. This analysis culminates in a novel, streamlined method that leverages drifting, a modern one-step generative sampler, to model the occupancy. We show that this enables policy extraction via direct differentiation through the occupancy model, and bypasses the need for critic distillation. Overall, we observe that this nimble setup leads to improvements in performance on standard benchmarks.
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cs.LGstat.ML Thomas Pammer, Johannes F\"urnkranz, Markus Sinnl · Oct 14, 2026

The paper studies how to learn interpretable binary classifiers as sparse Boolean rules by optimizing the weights of a fixed-structure DNF network. It proposes mixed integer linear programming (MILP) formulations that trade off training misclassification against rule sparsity, with an advanced formulation that dramatically reduces integer variables and redundant constraints while preserving exact Boolean semantics. A combined warm-start and dropout strategy is introduced to break symmetries and push scalability to larger datasets.

We study the problem of learning accurate and cognitively simple binary classifiers that are directly interpretable as Boolean rules. We propose mixed integer linear programming (MILP) formulations for training sparse disjunctive normal form (DNF) networks, viewed as small networks with a conjunctive hidden layer and a disjunctive output layer. Contrary to previous work that uses MILP for inductive rule learning, we start with a fixed network structure, for which we then find optimal weights. A regularized objective explicitly trades off misclassification costs against sparsity, yielding globally optimized rule sets. Our main technical contribution is an enhanced formulation that substantially reduces the number of integer decision variables and eliminates redundant constraints, while preserving exact Boolean semantics for all feasible solutions. Furthermore, we develop a combined approach based on initialization and dropout to break symmetries in the weights between rules, mitigating redundancy, and encouraging more diverse and stable rule representations. Experiments on synthetic benchmarks and UCI datasets show that the advanced formulation improves computational efficiency and achieves competitive or superior accuracy compared to established interpretable baselines, including SAT-based DNF learning and well-known rule- and tree-based learners. Overall, our approach provides a principled optimization framework for learning compact Boolean rule sets with explicit control over accuracy and sparsity trade-offs.
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cs.AIcs.LG Haofei Yu, Yixing Chen, Yining Zhao et al. · Oct 14, 2026

CoPE attacks the sample-efficiency bottleneck in training long-horizon language agents with reinforcement learning. Standard agentic RL such as GRPO optimizes only a sparse terminal reward $Y(\tau) \in \{0,1\}$, leaving the rich temporal structure of intermediate steps unused. The paper introduces CoPE, which augments GRPO with success-conditioned multi-step action forecasting: on successful on-policy trajectories, the shared policy backbone learns to predict future action chunks $a_{t:t+K}$ from each history $h_t$, so every action is supervised from both the moment it is taken and from the $K$ preceding histories. This implicit temporal ensemble yields stronger aggregate performance and up to $2\times$ sample-efficiency gains across five benchmarks, with no added inference cost.

Training language agents is bottlenecked by the high cost of long-horizon rollouts, yet standard agentic reinforcement learning (RL) learns only from a terminal scalar reward, leaving the supervision in intermediate steps largely unused. Prior work exploits this supervision through value targets that estimate per-step success probabilities or observation targets that fit environment response. Both are hard to construct well: (1) value targets come from the same single scalar signal for each step in the trajectory, and (2) observation targets, such as web pages and terminal logs, are long and noisy and reach only one step ahead. We propose \name, which adds a third kind of multi-step action targets. On successful on-policy trajectories, \name trains the policy backbone to generate the action sequences that follows each history. Each action is also supervised when forecast from the preceding histories, forming a temporal ensemble that the shared backbone absorbs during training, and this enables acting and forecasting to co-evolve. The policy still acts one step at a time at inference, with no overhead. Across five benchmarks (ALFWorld, ScienceWorld, WebShop, $\tau^2$-bench, and AppWorld), \name (1) achieves stronger aggregate performance than GRPO and RL baselines with predictive auxiliary targets across simulated environments, while improving overall performance on both realistic applications; (2) delivers up to $1.9\times$ and $2.0\times$ higher sample efficiency than ECHO and GRPO, respectively, on ScienceWorld; and (3) achieves these gains with a single policy backbone, without additional models, separate pretraining, or inference overhead. The codebase is available at https://github.com/ulab-uiuc/CoPE.
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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 "soft-token" 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.