collaborators

11 papers

cs.AI2026

The Model Knows, the Decoder Finds: Future Value Guided Particle Power Sampling

Tu Nguyen, Matthieu Zimmer, Rasul Tutunov +2

A recurring pattern in "reasoning without training" is that base LLMs already assign non-trivial probability mass to correct multi-step solutions; the bottleneck is locating these…

cs.AI2026

Risk-Controlled Lean-as-Judge for Natural-Language Mathematical Reasoning

Pauline Bourigault, Xiaotong Ji, Matthieu Zimmer +2

Lean is increasingly used to judge natural-language mathematical answers, but its signal is partial: many answers never formalize, and a failed proof may reflect an ill-typed state…

cs.LG2026

The -Combinator for LLMs: Solving Long-Context Rot with -Calculus

Amartya Roy, Rasul Tutunov, Xiaotong Ji +2

LLMs are increasingly used as general-purpose reasoners, but long inputs remain bottlenecked by a fixed context window. Recursive Language Models (RLMs) address this by externalisi…

cs.LG2026

Decoding as Optimisation on the Probability Simplex: From Top-K to Top-P (Nucleus) to Best-of-K Samplers

Xiaotong Ji, Rasul Tutunov, Matthieu Zimmer +1

Decoding sits between a language model and everything we do with it, yet it is still treated as a heuristic knob-tuning exercise. We argue decoding should be understood as a princi…

cs.CL2026

Multi-Task GRPO: Reliable LLM Reasoning Across Tasks

Shyam Sundhar Ramesh, Xiaotong Ji, Matthieu Zimmer +5

RL-based post-training with GRPO is widely used to improve large language models on individual reasoning tasks. However, real-world deployment requires reliable performance across…

cs.LG2026

Scalable Power Sampling: Unlocking Efficient, Training-Free Reasoning for LLMs via Distribution Sharpening

Xiaotong Ji, Rasul Tutunov, Matthieu Zimmer +1

Reinforcement learning (RL) post-training is a dominant approach for improving the reasoning performance of large language models (LLMs), yet growing evidence suggests that its gai…