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Sean O'Brien

2 papers indexed

arxivcs.LG2026-07-11

LeRoPE: Learnable RoPE Frequencies Improve Language Modeling

Petros Karypis, Sean O'Brien, Shreyas Kadekodi, Rui Zhu, Julian McAuley

Rotary Positional Encodings (RoPE) are currently the most popular positional encodings used in modern language models. RoPE rotates two-dimensional chunks of query and key vectors, operating as a function of their relative positional offset. The position-wise rates of rotation in…

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arxivcs.LGcs.AI2026-07-01

Don't Let Gains FADE: Breaking Down Policy Gradient Weights in RL

Juliette Decugis, Sean O'Brien, Francis Bach, Gabriel Synnaeve, Taco Cohen

Reinforcement learning post-training dramatically improves LLM reasoning, but suffers from training instability and diversity collapse. Advantage functions offer an appealing fix: they reshape the training objective, reweight which rollouts drive learning, and are trivial to impl…

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