Percy Liang, Stanford University @ Machine Learning Advances and Applications Seminar
Abstract: Models in deep learning are wild beasts: they devour raw data, are powerful but hard to control. This talk explores two approaches to taming them. First, I will introduce concept bottleneck networks, in which a deep neural network makes a prediction via interpretable, high-level concepts. We show that such models can obtain comparable accuracy with standard models, while offering the unique ability for a human to perform test-time interventions on the concepts. Second, I will introduce prefix-tuning, which allows one to harness the power of pre-trained language models (e.g., GPT-2) for text generation tasks. The key idea is to learn a continuous task-specific prefix that primes the language model for the task at hand. Prefix-tuning obtains comparable accuracy to fine-tuning, while only updating 0.1% of the parameters. Finally, I will end with a broad question: what kind of datasets should the community develop to drive innovation in modeling approaches? Are size and realism necessary attributes of a dataset? Could we have made all the modeling progress in NLP without SQuAD? As this counterfactual question is impossible to answer, we perform a retrospective study on 20 modeling approaches and show that even a small, synthetic dataset can track the progress that was made on SQuAD. While inconclusive, this result encourages us to think more critically about the value of datasets during their construction.
Bio: Percy Liang is an Associate Professor of Computer Science at Stanford University (B.S. from MIT, 2004; Ph.D. from UC Berkeley, 2011). His research spans many topics in machine learning and natural language processing, including robustness, interpretability, semantics, and reasoning. He is also a strong proponent of reproducibility through the creation of CodaLab Worksheets. His awards include the Presidential Early Career Award for Scientists and Engineers (2019), IJCAI Computers and Thought Award (2016), an NSF CAREER Award (2016), a Sloan Research Fellowship (2015), a Microsoft Research Faculty Fellowship (2014), and multiple paper awards at ACL, EMNLP, ICML, and COLT.