Ongoing events

Topos Institute Colloquium
Thursdays, 17:00 UTC

The Topos Institute Colloquium is an expository talk series showcasing work towards the Topos mission. This year’s themes are: ethics and societal impact of mathematics and computer science; applied category theory; foundation models: logic, categories, and type theory; and technologies and tools.

Berkeley Seminar
Mondays, 16:00 PT

The Topos Institute Berkeley Seminar is a weekly, informal seminar on topics relevant to the Topos Institute Community, held in-person at our Berkeley Campus.

Public calendar

Past events

Poly @ Work
February – March 2024

Polynomial functors are a ‘prime example of mathematics’ startling capacity to yield deep formal insights and real-world applications from the simplest ingredients. The category of polynomial functors (Poly) offers an abundance of elegant theory linked with computational design patterns that span the entire abstraction hierarchy. It is a rich playground in which ideas from different disciplines naturally collide. This workshop brought together students, researchers, and practitioners from around the world to learn, share, and collaborate on the theory and applications of polynomial functors.

The Joy of Abstraction Book Club
February – October 2023

The Joy of Abstraction, by Eugenia Cheng, is an introduction to category theory for anyone who wants to get into the formality of the subject but does not necessarily have the mathematical background to read a standard textbook. Dr Cheng would like to give people an opportunity to ask questions and get help with understanding the book. The book club will be run asynchronously. We will go at an approximate rate of one chapter per week and invite any readers to submit questions for each chapter according to a published schedule. We will then collate the questions and Dr Cheng will make a video each week addressing the questions for that chapter.

Workshop on Category Theory for Consciousness Science
15–16 of April 2023

Category theory has established itself as an important tool in the applied sciences, and recently approaches have emerged which apply category theory to the study of cognition and consciousness. This two day workshop aims to bring together researchers from a wide range of backgrounds who are interested in the application of formal methods and category theory in consciousness science.

CT Outreach Panel
16 March 2023

Category theory is a wonderful subject, deep and broad, spanning the breadth of mathematics and having applications throughout science, engineering, technology, and the arts. But for people outside of academia, it can be a difficult subject to learn. Topos Institute is hosting a panel discussion, moderated by Emily Riehl, to help people get a better handle on how they may begin to learn the subject and to help category theorists understand what they can do to facilitate this process.


Intercats is a seminar series on the theory and applications of the mathematics of interacting systems, with a focus on category-theoretic tools for information-processing or adaptive systems, or those with a ‘bidirectional’ relationship to an environment.

2022 Workshop on Polynomial Functors
14–18 March 2022

The 2022 Workshop on Polynomial Functors will cover both background material and the latest progress on polynomial functors. The main topic is the notion of polynomial functors in locally cartesian closed categories, as employed in logic and type theory (the theme of the previous year’s workshop).

Em-Cats Virtual Seminar 21/22
August 2021 – May 2022

The Emerging Researchers in Category Theory (Em-Cats) Virtual Seminar is a series given by graduate students in Category Theory around the world. Eugenia Cheng assists each speaker in preparing their talk.

Polynomial Functors Course
15 July – 26 August 2021

The category of polynomial functors is a fascinating setting, brimming with rich mathematics and tantalizing applications. In this course, we will investigate these polynomials, with emphasis on their applications to dynamical systems, decisions, and data. We aim to strike a balance between a solid theoretical foundation and a breadth of examples.

Finding the Right Abstractions
May 2021

Applied category theory (ACT) has many useful tools for creating and layering flexible abstractions, and Topos is seeking ways to apply these tools to important problems. Many in the AI safety community feel a need for new good abstractions to ground their thinking about intelligence, agency, and optimization. This hammer and nail situation suggests an opportunity for collaboration in applying ACT tools to advance human flourishing, and this workshop is intended to start the conversion in earnest.

2021 Workshop on Polynomial Functors
15–19 March 2021

Participants will learn background material and hear the latest progress on polynomial functors, monads, and comonads, their algebras and coalgebras, as well as on operads, parametric right adjoints, and cofunctors, with applications to combinatorics, database theory, dynamical systems, higher category theory, logic, and type theory.