Stephen Zhao

Computer Science PhD student @UofT

[Stephen Zhao @ZhaoStep]

Full paper: https://t.co/wPaKRvPZzi. If you're at NeurIPS2025, come see us at Exhibit Hall C,D,E - Poster #3407, on Wednesday, Dec 3, 11 AM – 2 PM PST!

[Stephen Zhao @ZhaoStep]

RL methods like PPO reduce the probability of sampled low-reward sequences. With training, these outputs become rare, with weaker gradient signal. We can better reduce their probabilities using probabilistic inference to aid sampling! (with @aidanmrli @brekelmaniac @RogerGrosse)

[Stephen Zhao @ZhaoStep]

Furthermore, RePULSe can provide better adversarial robustness (to a GCG adversarial attack).

[Transluce @TransluceAI]

Announcing Transluce, a nonprofit research lab building open source, scalable technology for understanding AI systems and steering them in the public interest.

Read a letter from the co-founders Jacob Steinhardt and Sarah Schwettmann:
https://t.co/IUIhBjpYhS

[Stephen Zhao @ZhaoStep]

Check out the full paper here: https://t.co/ZFmgdnEJs2. Our code is also available: https://t.co/pV1bPfLrTw).

[Stephen Zhao @ZhaoStep]

RL is not the only paradigm for language model alignment or controlled generation!
Let’s take a principled probabilistic approach: define a target distribution, perform inference, estimate KLs. Enter our work on twisted SMC for LMs with @brekelmaniac* @AliMakhzani @RogerGrosse

[Stephen Zhao @ZhaoStep]

We use our bidirectional SMC bounds to evaluate inference methods (including PPO) in these settings, via forward and reverse KL divergences between the model q(𝐬) and target σ(𝐬) distributions, showing our framework’s ability to provide meaningful quantitative evaluation.

[Stephen Zhao @ZhaoStep]

If you're at NeurIPS come visit our poster at 403!

[Stephen Zhao @ZhaoStep]

SOTA AI algorithms in general-sum settings often result in worst case collective outcomes. Opponent shaping (eg LOLA https://t.co/KloekN99YB) partially addresses this. We show that prior work is sensitive to policy parameterization and introduce a novel method to solve this issue

[Stephen Zhao @ZhaoStep]

Check out the full paper: https://t.co/0qtvS6swFY, come see us at NeurIPS in person or online: https://t.co/9yOipvWFWJ, and/or send comments and questions our way!