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#artificial intelligence Preprint Open access Oct 2026

When LLM Reward Design Fails: Diagnostic-Driven Refinement for Sparse Structured RL

For sparse, structured reinforcement-learning tasks with semantic reward-function interfaces, LLM-generated reward shaping is better framed as debugging than one-shot generation. We study PPO-trained agents using MiniGrid as core evaluation and MuJoCo reaching/locomotion as boundary stress tests. Our qualitative audit...

Youting Wang, Yuan Tang, Bowen Liu et al. · 0 citations
#artificial intelligence Preprint Open access Oct 2026

How Do Uncertainty Estimators Align with Hallucination Occurrence in LLMs?

Large language models (LLMs) can hallucinate, but do model uncertainty estimators reliably reveal when they do? Although uncertainty estimators are increasingly used to identify unreliable generations, their relationship with hallucination remains poorly understood and is often taken for granted. We systematically eval...

Yedidia Agnimo, Anna Korba, Annabelle Blangero et al. · 0 citations
#artificial intelligence Preprint Open access Oct 2026

GAC: Noise-Aware Adaptive Mixing for Hybrid SFT-RL Post-Training

Hybrid post-training combining supervised fine-tuning (SFT) and reinforcement learning (RL) is the standard paradigm for aligning large language models, yet fixed mixing schedules cannot adapt when the relative noise of the two signals evolves. We derive a noise-aware mixing weight mu* by minimizing an MSE upper bound...

Yuelin Hu, Wei Liu, Zhenbo Yu et al. · 0 citations
#artificial intelligence Preprint Open access Oct 2026

Exact Symmetry as Algebra: Group-Structured Tensors that Enforce Physical Selection Rules

Symmetry determines which physical responses of molecules and crystals are allowed and underlies many models used throughout the physical sciences. Yet several widely used machine-learned models learn symmetry only approximately from data, raising the question of whether approximate symmetry is sufficient for scientifi...

Paulina Hoyos, Shashanka Ubaru, Dongsung Huh et al. · 0 citations
#artificial intelligence Preprint Open access Oct 2026

Training data attribution in diffusion models via mirrored unlearning and noise-consistent skew

Training data attribution (TDA) should enable generative model interpretability and foster a variety of related downstream tasks. Nonetheless, current TDA approaches lack reliability and robustness, preventing their adoption in real-world setups. In this paper, we take a decisive step towards more reliable and robust T...

Joan Serr\`a, Dipam Goswami, Fabio Morreale et al. · 0 citations
#artificial intelligence Preprint Open access Oct 2026

$\boldsymbol{f}$-OPD: Stabilizing Long-Horizon On-Policy Distillation with Freshness-Aware Control

Scaling on-policy distillation (OPD) for large language models (LLMs) confronts a fundamental tension: asynchronous execution is necessary for system efficiency, but structurally deviates from the ideal on-policy objective. To address this challenge, we theoretically decompose the objective discrepancy into rollout dri...

Xianwei Chen, Shimin Zhang, Jibin Wu · 0 citations
#artificial intelligence Preprint Open access Oct 2026

Learning Higher-Order Interactions from Incomplete Spatiotemporal Data with Mixtures of Hypergraph Laplacians

Traffic sensor data exhibit strong temporal and cross-sensor dependencies, yet long gaps erase both a sensor's local history and the joint observations needed to learn its relationships with other sensors. We introduce MoHL, a mixture of hypergraph Laplacians that learns group-wise relational structure directly from in...

Keshu Wu, Sixu Li, Zihao Li et al. · 0 citations
#artificial intelligence Preprint Open access Oct 2026

LoopQ: Quantization for Looped Language Models

Looped language models (LoopLMs) increase effective computational depth by repeatedly applying shared Transformer blocks without increasing the parameter count. However, this reuse makes them particularly sensitive to post-training quantization (PTQ). We systematically study PTQ in LoopLMs and identify three sources of...

Rui Fang, Hsi-Wen Chen, Chia-Ming Cheng et al. · 0 citations
#artificial intelligence Preprint Open access Oct 2026

$\alpha$-TCAV: A Unified Framework for Testing with Concept Activation Vectors

Concept Activation Vectors (CAV) and the Testing with CAVs (TCAV) method are fundamental tools for concept-based explainability in deep learning, yet their practical utility is limited by the variability across different samples of concept and non-concept examples. We analyze this stochastic nature of CAVs, and identif...

Ekkehard Schnoor, Jawher Said, Malik Tiomoko et al. · 0 citations
#artificial intelligence Preprint Open access Oct 2026

Concurrency without Model Changes: Future-based Asynchronous Function Calling for LLMs

Function calling, also known as tool use, is a core capability of modern LLM agents but is typically constrained by synchronous execution semantics. Under these semantics, LLM decoding is blocked until each function call completes, resulting in increasing end-to-end latency. In this work, we introduce AsyncFC, a pure e...

Guangyu Feng, Huanzhi Mao, Prabal Dutta et al. · 0 citations

Discrete MeanFlow: One-Step Generation via Conditional Transition Kernels

Discrete MeanFlow is introduced, a theoretical finite-state formulation that replaces point motion with probability-mass transport and validate the identity on exact finite-state Markov chains, demonstrating that the learned kernel recovers the analytical ground truth with high precision.

Fairoz Nower Khan, Nabuat Zaman Nahim, Md Sajid Ahmed et al. · 2 citations
#artificial intelligence Preprint Open access Oct 2026

Beyond GRPO and On-Policy Distillation: An Empirical Sparse-to-Dense Reward Principle for Language-Model Post-Training

In settings where labeled verifiable training data is the binding constraint, each checked example should be allocated to the model and reward density where it is most informative. We identify a reward-density principle: sparse sequence-level reward is most useful on models that can explore and discover better behavior...

Yuanda Xu, Hejian Sang, Zhengze Zhou et al. · 0 citations

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MIT News · Artificial Intelligence Oct 23, 2026

Q&A: How AI came to model the “messy” human mind

Assistant Professor Benjamin Lindquist studies how engineers deliberately injected randomness into early AI, giving rise to deep-learning models that sometimes hallucinate.

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