Spotlight · Tue PM · unbiased importance sampling
Large language models can exhibit emergent reasoning behaviors, often manifested as recurring lexical patterns (e.g., "wait," indicating verification). However, complex reasoning trajectories remain sparse in unconstrained sampling, and standard RL often fails to guarantee the acquisition of diverse reasoning behaviors. We propose systematic discovery and reinforcement of diverse reasoning patterns through structured reasoning, a paradigm that requires targeted exploration of specific reasoning patterns during RL. Ctrl-R is a framework for learning structured reasoning via tractable trajectory control that actively guides the rollout process, incentivizing the exploration of diverse reasoning patterns. The resulting behavior policy enables accurate importance-sampling estimation, supporting unbiased on-policy optimization. We introduce a power-scaling factor on the importance-sampling weights, allowing selective learning from out-of-distribution trajectories.
Spotlight · Qwen 2.5/3 +15-21% pass@1 · self-critique +16.7% AIME
Recent advances in RL using numerical rewards have significantly enhanced the complex reasoning capabilities of LLMs. However, we identify three fundamental limitations of purely numerical feedback: performance plateaus, ineffective spontaneous self-reflection, and persistent failures. We show that plateaued RL models can successfully refine failed solutions when given natural language critiques. Critique-GRPO is an online RL framework that integrates both natural language and numerical feedback for policy optimization, enabling LLMs to learn simultaneously from initial responses and critique-guided refinements. Critique-GRPO outperforms all compared supervised and RL-based fine-tuning methods, achieving average Pass@1 improvements of approximately +15.0-21.6% on Qwen models and +7.3% on Llama-3.2-3B-Instruct across eight challenging reasoning tasks. Notably, Critique-GRPO facilitates effective self-improvement through self-critiquing, achieving +16.7% Pass@1 on AIME 2024.
Spotlight · MIT/FAIR · Wed · bi-level meta-RL curriculum
RL methods for finetuning large reasoning models stall on datasets with low initial success rates, and thus little training signal. Can a pretrained LLM leverage latent knowledge to generate an automated curriculum for problems it cannot solve? SOAR is a self-improvement framework to surface pedagogical signals through meta-RL. A teacher model proposes synthetic problems for a student model, rewarded with the student's improvement on a subset of hard problems, grounding the curriculum in real student progress rather than proxy rewards. Study on hardest subsets of math benchmarks (0/128 success) reveals: (1) bi-level meta-RL unlocks learning under sparse binary rewards by sharpening pretrained models' latent capacity to generate useful problems; (2) grounded rewards outperform intrinsic rewards, reliably avoiding instability and diversity collapse; (3) the structure and well-posedness of questions matter more for learning progress than solution correctness.
ICML Oral 2A · Qwen3-235B max 5.35× walltime
Speculative Decoding promises to accelerate LLM inference, yet its efficacy often degrades in production-grade scenarios. Existing approaches struggle under high-concurrency conditions where verification compute dominates performance. Static trees cause substantial verification overhead, while dynamic trees encounter cumulative errors and compatibility issues. ECHO, a framework within SGLang, treats speculative execution as a budgeted scheduling challenge. Using sparse confidence gating, it manages batches as a unified super-tree, dynamically adjusting computational resources between depth and width dimensions. Testing across multiple model scales including the industrial Qwen3-235B shows ECHO achieves up to 5.35× walltime speedup and outperforms competing approaches by over 20% in both low and high-load scenarios.
ICML Oral 1A · Data Wall 시대 · GPT-2 XL 30B beats 200B full
As high-quality public text approaches exhaustion — the Data Wall — LLM pre-training is shifting from more tokens to better tokens. Existing methods either rely on heuristic static filters that ignore training dynamics, or use dynamic yet optimizer-agnostic criteria based on raw gradients. OPUS (Optimizer-induced Projected Utility Selection) is a dynamic framework that defines utility in the optimizer-induced update space. OPUS scores candidates by projecting their effective updates, shaped by modern optimizers, onto a target direction derived from a stable in-distribution proxy. We employ Ghost technique with CountSketch for computational efficiency and Boltzmann sampling for diversity, incurring only 4.7% additional compute overhead. In pre-training of GPT-2 Large/XL on FineWeb and FineWeb-Edu with 30B tokens, OPUS outperforms industrial-level baselines and even full 200B-token training. On Qwen3-8B CPT on SciencePedia, OPUS achieves superior performance with only 0.5B vs 3B tokens.
ICML Oral 1A · shared feature space across LLaMA/Mistral/Qwen
The diversity of post-training data is critical for effective downstream performance in LLMs. Many existing approaches quantify diversity using text-based metrics that capture linguistic variation, but such metrics provide only weak signals for the task-relevant features. We introduce Feature Activation Coverage (FAC), which measures data diversity in an interpretable feature space. Building on this metric, we propose FAC Synthesis — a diversity-driven data synthesis framework that first uses a sparse autoencoder to identify missing features from a seed dataset, and then generates synthetic samples that explicitly reflect these features. Experiments show consistent improvements on instruction following, toxicity detection, reward modeling, and behavior steering. We identify a shared, interpretable feature space across model families (LLaMA, Mistral, Qwen), enabling cross-model knowledge transfer.
ICML Oral 2A · arXiv 미확인 · 60% head 되돌려도 +4%
Continual pre-training is examined as a strategy for customizing broad language models to specific domains including mathematics, code, instruction, and natural language. Through singular value decomposition of weight matrices, we discovered that continual pre-training leaves singular value spectra largely invariant, with adaptation driven mainly by changes in singular vectors. Attention-head projection matrices show significant domain-dependent head heterogeneity. This enabled importance metrics showing up to 60% of head updates can be removed without measurable quality loss. Strategically reverting less important heads to pre-trained weights enhanced benchmark performance by up to 4%. We discovered domain connectivity through linear checkpoint interpolation, demonstrating smooth quality transitions between domains. We release Diffract, an open-source toolkit for spectral analysis.