Large language models

Model releases, architecture work and prompting research on large language models — from frontier-lab announcements to the arXiv papers behind them.

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arXiv Machine Learning
Sep 29

Low-Bit Recurrent States in Hybrid Language Models

The paper introduces a method for quantizing the fixed‑size recurrent states of hybrid language models to as few as four bits per token. By deriving distortion weights from the observability Gramian and combining them with normalized state ranges, the authors achieve mixed‑precision bit allocation without requiring calibration data, rotation, or additional training. The approach also logarithmically quantizes decay rates, yielding significant reductions in excess negative log‑likelihood—up to 27.9× better than seven baselines—while maintaining near‑FP32 performance at six bits.

By Hongren Chen, Jiayang He
arXiv Machine Learning
Sep 29

The Residual Stream's Effective Depth

The paper introduces effective depth (Deff), a scalar diagnostic that treats a transformer’s layer‑wise residual stream as a discrete‑time process and measures how representation similarity decays with layer distance. Across sixteen decoder‑only language models, Deff reveals that most models exhibit a lower similarity decay than the closed‑form reference, indicating correlated residual updates rather than unused depth. The study also shows that this effect is robust to various controls and persists early in training, suggesting Deff is a global accumulated‑state diagnostic rather than a capability score.

By Barak Gahtan, Ido Galil, Alex M. Bronstein
arXiv Machine Learning
Sep 29

Towards Understanding LLM-Based Log Anomaly Detection: An Empirical Study of Performance, Efficiency, and Robustness

The paper investigates how different adaptation strategies, model architectures, parameter scales, and quantization settings influence the performance, efficiency, and robustness of large language models (LLMs) for log anomaly detection. Across three public log datasets, the study finds that adaptation strategies lead to significant performance variations, model scaling offers dataset‑dependent gains, and models with similar accuracy can differ markedly in computational cost. Low‑bit quantization largely preserves detection performance, and the authors also assess robustness to structural, semantic, and label noise at varying perturbation levels.

By Bin Li, Dongdong Wang, Siyang Lu
arXiv Machine Learning
Sep 29

Trust Guided Decision Transformer

The paper introduces Trust Guided Decision Transformer (TGDT), a method that mitigates performance degradation in Decision Transformers during long rollouts by monitoring the model’s next‑state prediction error. TGDT evaluates multiple recent context suffixes, filters out those whose prediction error exceeds a calibrated threshold, and then selects the highest‑value action from the remaining trusted suffixes using a frozen critic. Experiments on D4RL navigation and locomotion tasks demonstrate that TGDT reduces persistent high‑error runs and improves returns compared to vanilla Decision Transformer and other context‑control baselines.

By Chainesh Gautam, Raghuram Bharadwaj Diddigi, Chandramouli Kamanchi, Pankaj Dayama, Sumanta Mukherjee, Kameshwaran Sampath
arXiv Machine Learning
Sep 29

New LoRA Skills Should Read but Never Write

The paper introduces READ, a method for composing low‑rank adapters (LoRA) in large language models. By rewriting each adapter into a balanced canonical form and enforcing a one‑directional coupling, READ allows new skills to read but never write into the output subspaces of existing skills, eliminating interference. Experiments on four benchmark suites and two model families show that READ consistently outperforms existing baselines, improving SuperGLUE scores by over twenty points and domain suite scores by more than seven points.

By Zeyan Li, Panqi Yang, Qirong Guo, Shengda Zhuo, SIyuan Qiu, Hu Xu, Chun Li, Jianfeng Xu
arXiv Machine Learning
Sep 29

Adaptive Multi-Value Control in LLMs via Causal Activation Steering

The paper introduces AIMES, a framework for adaptive multi-value activation steering in large language models. AIMES builds layer‑specific bipolar directions for moral‑foundation values and uses intermediate‑layer vocabulary readouts as online observers to guide a controller that adjusts intervention strengths at each decoding step. Experiments across instruction‑tuned model families show that AIMES achieves depth‑dependent advantages over fixed joint steering and prompt‑based steering, with smaller activation‑space interventions and comparable response quality.

By Payel Bhattacharjee, Ravi Tandon
arXiv Machine Learning
Sep 29

From Weak Data to Strong Policy: Q-Targets Enable Provable In-Context Reinforcement Learning

The paper introduces Q-Target Pretrained Transformers (QTPT), a method that replaces supervised behavior cloning with a Bellman-style Q‑target objective for in‑context reinforcement learning. QTPT retains the context‑conditioned Transformer architecture but learns to estimate action values using rewards and transitions from the context, rather than merely imitating offline actions. The authors provide theoretical analysis in stochastic linear bandits and finite‑horizon MDPs, demonstrating improved robustness to weak or suboptimal data, and empirically show gains over supervised pretraining on controlled RL benchmarks and extensions to D4RL Kitchen and AntMaze.

By Yichen Lin, Xuyuan Xiong, Xue Wang, Xiangfu Meng, Mike Mingcheng Wei, Tao Yao
arXiv Machine Learning
Sep 29

Parameters vs. Context: TRACE Fine-Tuning for Robust Retrieval-Augmented Generation

The paper introduces TRACE, a fine‑tuning framework for Retrieval‑Augmented Generation (RAG) that addresses conflicts between retrieved knowledge and a model’s internal knowledge. TRACE uses multi‑agent debate traces to identify correct and incorrect candidates and answer‑shift patterns, providing fine‑grained supervision for reliable knowledge‑source selection. It also incorporates an answer‑completeness regularization mechanism to prevent empty, overly short, or prematurely terminated responses, thereby improving robustness against misleading retrieved content and enhancing answer quality.

By Zhengchen Huang, Yundong Sun, Minrui Song, Shuanglong Yao, Ye Liu, Ji Chen, Xing Wang
arXiv Machine Learning
Sep 29

Fake News Theories: Harnessing Disciplinary Insights for Computational Modeling, Detection, and Explanation

The paper presents a theory-informed computational framework that converts cross-disciplinary theories of fake news into measurable features for automated detection and explanation. By reviewing theories from social sciences, psychology, economics, and more, the authors establish a broad theoretical foundation for computational modeling. Experiments on benchmark datasets demonstrate that theory-derived features are predictive, provide interpretable diagnostic signals, and that multi-feature models generally outperform individual features, though gains are modest.

By Zhaoyang Cao, Miriam Metzger, Reza Zafarani
arXiv Machine Learning
Sep 29

Reinforcement Learning of Communication in a Mesh of Small Language Models

The paper introduces TalkMesh, a decentralized network of small language model agents that learn to communicate effectively during inference. Each agent proposes an answer, scores it with a confidence head, and the most confident agent broadcasts a hint; lower‑confidence agents revise their proposals if a new suggestion scores higher. This gossip‑based consensus, trained via group relative policy optimization, enables a mesh of three agents to match the accuracy of majority voting over 32 samples, and scales to larger meshes to significantly boost performance on benchmarks like GSM8K and MATH-500.

By Mehmet Kerem Turkcan
arXiv Machine Learning
Sep 29

LUMO (Lightweight Unified Multilingual Orchestrator): A Privacy Preserving Offline Voice Assistant

LUMO (Lightweight Unified Multilingual Orchestrator) is a privacy‑preserving offline voice assistant that runs entirely on edge hardware, specifically a Raspberry Pi 5 with 8 GB RAM. It integrates local ASR, a 4‑bit GGUF‑quantized LLM, and TTS to deliver end‑to‑end response latencies of 2.0–4.0 s, a 6.8 % WER on short English utterances, and lower peak power consumption (~9 W) compared to existing edge assistants. The system also supports Bangla speech, enabling multilingual use in low‑resource settings.

By Md. Mehedi Hasan Naeem, Mst. Kamrunnahar Ruma, Nafiza Anjum, Shakila Sultana, Md. Sujan Ali
arXiv Machine Learning
Sep 29

Mechanism-Aware Ensemble Conditioning for Data-Limited Emulation of Extreme Events

The paper introduces a mechanism‑aware conditioning framework that uses a nudged coarse ensemble to capture local instability geometry in chaotic systems. By injecting ensemble covariance statistics via a small FiLM module, the authors enhance rare‑event emulation in both a low‑dimensional chaotic benchmark and a quasi‑geostrophic flow model, achieving significant improvements in exceedance‑frequency and tail‑density errors with limited data. The approach demonstrates that local instability information can be leveraged as a practical conditioning signal for data‑efficient emulation of extreme events.

By Isabella S. Thiel, Juan Bello-Rivas, Yannis G. Kevrekidis, Themistoklis P. Sapsis
arXiv Machine Learning
Sep 29

CacheReforge: Bounded Recovery for Stale KV Caches under Evolving Adapters

CacheReforge is a method for recovering stale key‑value (KV) caches in large language models when lightweight adapters evolve. It represents stale caches as layer‑wise mixed‑version objects and uses adapter anchors, sensitivity calibration, drift accumulation, and restart boundaries to decide between direct reuse, bounded recomputation, or full suffix recovery. Experiments on Qwen2.5 models with continual LoRA updates show a 92.4% reduction in mean KL divergence while only recomputing 5.44% of layers and cutting cache‑maintenance time by 93.2% compared to full prefill.

By Yuhang Cao, Yanzhou Mu, Chunrong Fang, Zhenyu Chen
arXiv Machine Learning
Sep 29

Towards Understanding Momentum Acceleration in River-Valley Loss Landscape

The paper investigates how momentum influences optimization in a river‑valley loss landscape, where a low‑loss manifold is surrounded by steep orthogonal directions. It shows that momentum stabilizes large learning rates that vanilla gradient descent cannot tolerate, enabling faster progress along the river. The study also finds that in very flat, slowly spinning rivers, momentum itself does not directly accelerate tracking, but the larger permissible learning rate does.

By Miao Lu, Zeyu Bian, Kaiyue Wen, Beining Wu, Siyu Chen, Tianhao Wang, Zhiyuan Li
arXiv Machine Learning
Sep 29

Self-Supervised Representation Learning: From Spectral Foundation Models to Auroral Emission Spectra

The paper presents a self‑supervised approach to learning representations of auroral emission spectra using a 1D Vision Transformer trained with a masked autoencoder on 223,000 unlabelled spectra. The pretrained model recovers key emission‑line intensity ratios with high accuracy (R² = 0.91) and, with a single linear probe, matches expert‑designed feature classifiers. When fine‑tuned, it surpasses the previous supervised auroral classifier (macro‑AP 88.5 vs. 77.8) and achieves a 0.870 mAP, outperforming a model trained from scratch by 0.159 using only 10 % of the labels, while attribution reveals reliance on N₂⁺ bands.

By Matthieu Le Lain, Ga\"el Cessateur, S\'ebastien Lef\`evre
arXiv Machine Learning
Sep 29

A Comprehensive Study of Content Representations for Speech Synthesis

The paper investigates how different speech content representations—such as SSL features, supervised tokens, posteriorgrams, and neural audio codecs—perform when used to train a generative model that produces audio conditioned only on each representation. By evaluating the generated audio on content, speaker identity, and prosody, the study identifies two regimes: some representations almost fully reconstruct the original audio, while others effectively separate speaker identity. The findings reveal that disentanglement of speaker identity depends on both the training objective and the representation’s information capacity, rather than supervision alone.

By Diego Torres, Axel Roebel, Nicolas Obin