The Cartesian Cafe
The Cartesian Cafe
Timothy Nguyen
Tai-Danae Bradley | Category Theory and Language Models
2 hour 25 minutes Posted Aug 22, 2022 at 4:31 am.
: Introduction
: How did you get into category theory?
: Outline of podcast
: Motivating category theory
: Analogy: Object Oriented Programming
: Definition of category
: Example: Category of sets
: Example: Matrix category
: Example: Preordered set (poset) is a category
: Example: Category of finite-dimensional vector spaces
: Forgetful functor
: Fruity example of forgetful functor: Forget race, gender, we're all part of humanity!
: Definition of functor
: Example: API change between programming languages is a functor
: Example: Groups, group homomorphisms are categories and functors
: Resume definition of functor
: Example: Functor between poset categories = order-preserving function
: Hom Functors. Things are getting meta (no not the tech company)
: Category theory is beautiful because of its rigidity
: Contravariant functor
: Definition: Presheaf
: Why are things meta? Arrows, arrows between arrows, categories of categories, ad infinitum.
: Probing a space with maps (prelude to Yoneda Lemma)
: Algebraic topology motivated category theory
: Definition: Natural transformation
: Example: Indexing category
: Example: Change of currency as natural transformation
: Isomorphism and natural isomorphism
: Notion of isomorphism in different categories
: Yoneda Lemma
: Example for Yoneda Lemma: Identity functor and evaluation natural transformation
: Analogy between Yoneda Lemma and linear algebra
: Corollary of Yoneda Lemma: Isomorphism of objects = Isomorphism of hom functors
: Yoneda embedding is fully faithful. Reasoning about this.
: Language Category
: Tai-Danae's paper: "An enriched category theory of language: from syntax to semantics"
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Show notes
Tai-Danae Bradley is a mathematician who received her Ph.D. in mathematics from the CUNY Graduate Center. She was formerly at Alphabet and is now at Sandbox AQ, a startup focused on combining machine learning and quantum physics. Tai-Danae is a visiting research professor of mathematics at The Master’s University and the executive director of the Math3ma Institute, where she hosts her popular blog on category theory. She is also a co-author of the textbook Topology: A Categorical Approach that presents basic topology from the modern perspective of category theory.
In this episode, we provide a compressed crash course in category theory. We provide definitions and plenty of basic examples for all the basic notions: objects, morphisms, categories, functors, natural transformations. We also discuss the first basic result in category theory which is the Yoneda Lemma. We conclude with a discussion of how Tai-Danae has used category-theoretic methods in her work on language modeling, in particular, in how the passing from syntax to semantics can be realized through category-theoretic notions.
Patreon: https://www.patreon.com/timothynguyen
Originally published on July 20, 2022 on YouTube: https://youtu.be/Gz8W1r90olc
Timestamps:
Further Reading:
Tai-Danae's Blog: https://www.math3ma.com/categories
Tai-Danae Bradley. "What is applied category theory?" https://arxiv.org/pdf/1809.05923.pdf
Tai-Danae Bradley, John Terilla, Yiannis Vlassopoulos. "An enriched category theory of language: from syntax to semantics." https://arxiv.org/pdf/2106.07890.pdf