In episode 65 of The Gradient Podcast, Daniel Bashir speaks to Sewon Min.
Sewon is a fifth-year PhD student in the NLP group at the University of Washington, advised by Hannaneh Hajishirzi and Luke Zettlemoyer. She is a part-time visiting researcher at Meta AI and a recipient of the JP Morgan PhD Fellowship. She has previously spent time at Google Research and Salesforce research.
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Outline:
(00:00) Intro
(03:00) Origin Story
(04:20) Evolution of Sewon’s interests, question-answering and practical NLP
(07:00) Methodology concerns about benchmarks
(07:30) Multi-hop reading comprehension
(09:30) Do multi-hop QA benchmarks actually measure multi-hop reasoning?
(12:00) How models can “cheat” multi-hop benchmarks
(13:15) Explicit compositionality
(16:05) Commonsense reasoning and background information
(17:30) On constructing good benchmarks
(18:40) AmbigQA and ambiguity
(22:20) Types of ambiguity
(24:20) Practical possibilities for models that can handle ambiguity
(25:45) FaVIQ and fact-checking benchmarks
(28:45) External knowledge
(29:45) Fact verification and “complete understanding of evidence”
(31:30) Do models do what we expect/intuit in reading comprehension?
(34:40) Applications for fact-checking systems
(36:40) Intro to in-context learning (ICL)
(38:55) Example of an ICL demonstration
(40:45) Rethinking the Role of Demonstrations and what matters for successful ICL
(43:00) Evidence for a Bayesian inference perspective on ICL
(45:00) ICL + gradient descent and what it means to “learn”
(47:00) MetaICL and efficient ICL
(49:30) Distance between tasks and MetaICL task transfer
(53:00) Compositional tasks for language models, compositional generalization
(55:00) The number and diversity of meta-training tasks
(58:30) MetaICL and Bayesian inference
(1:00:30) Z-ICL: Zero-Shot In-Context Learning with Pseudo-Demonstrations
(1:02:00) The copying effect
(1:03:30) Copying effect for non-identical examples
(1:06:00) More thoughts on ICL
(1:08:00) Understanding Chain-of-Thought Prompting
(1:11:30) Bayes strikes again
(1:12:30) Intro to Sewon’s text retrieval research
(1:15:30) Dense Passage Retrieval (DPR)
(1:18:40) Similarity in QA and retrieval
(1:20:00) Improvements for DPR
(1:21:50) Nonparametric Masked Language Modeling (NPM)
(1:24:30) Difficulties in training NPM and solutions
(1:26:45) Follow-on work
(1:29:00) Important fundamental limitations of language models
(1:31:30) Sewon’s experience doing a PhD
(1:34:00) Research challenges suited for academics
(1:35:00) Joys and difficulties of the PhD
(1:36:30) Sewon’s advice for aspiring PhDs
(1:38:30) Incentives in academia, production of knowledge
(1:41:50) Outro
Links:
Papers
Solving and re-thinking benchmarks
Language Modeling
Text representation/retrieval
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