Lewis Tunstall is a Machine Learning Engineer at Hugging Face, whose work lies at the intersection of the open-source and research teams. He is the co-author of the bestseller “NLP with Transformers” book and has previously built machine learning-powered applications for start-ups and enterprises in the domains of NLP, topological data analysis, and time series. He holds a PhD in Theoretical Physics, was a 2010 Fulbright Scholar and has held research positions in Australia, the USA, and Switzerland. His current work focuses on building tools and recipes to align language models with human and AI preferences through techniques like reinforcement learning.