Category Theory OctoberFest is an informal meeting, covering all areas of category theory and its applications. It is traditionally held in October.

2018 Meeting

OctoberFest 2018 took place in New York City at City College, which is part of the City University of New York, during the weekend of October 27/28, 2018.

Invited talk on Friday, October 26, 7pm:
Speaker: André Joyal
Title: Homotopy type theory: a new bridge between logic, category theory and topology
Abstract: Martin-Lôf type theory is a language for constructive mathematics with applications to program verifications and proof assistants. The homotopy interpretation of Martin-Lôf type theory, discovered by Voevodsky and independantly by Awodey and Warren, has initiated a project for a new foundation of constructive mathematics and of homotopy theory. An elementary notion of higher topos is emerging in the process. We shall describe the various connections involved.

(hosted by the NYC Category Theory Seminar)
(Slides, and Video)

OctoberFest time and location:
Sat. 9am – 6pm
Sun. 9am – 1pm

304 Shepard Hall
160 Convent Ave
New York, NY 10031

2018 organizers: Gershom Bazerman, Jonathon Funk, Pieter Hofstra, Benjamin Steinberg, Noson Yanofsky
Contact the organizers at

Program and abstracts.

Octoberfest 2018 was sponsored in part by the Dean of Science of City College of New York, the Mathematics Department of City College, and the NY Haskell Users Group


We suggest the upper west side or midtown as those areas are relatively near both the Grad center and CCNY. Possible hotels and hostels are the Hudson Hotel (58th St. and 9th Ave.) , or the HI NYC Hostel (891 Amsterdam).

Speakers (with slides where provided)

Mathieu Anel Cotopological towers of topoi and Goodwillie towers
Steve Awodey An algebraic fibrant replacement for cubical sets
Michael Barr On contractible simplicial objects and homotopies
Tai-Danae Bradley, Martha Lewis, Jade Master, Brad Theilman Modeling Language and Translations Categorically
Phillip Bressie Globular PROs as Cartesian-Duoidal Enriched Monoidal Categories
Christoph Dorn Combinatorial Cobordisms
Brendan Fong Hypergraph categories as cospan algebras
Nick Gurski The bar construction as cofibrant replacement
Gregory Henselman-Petrusek Functoriality in Topological Models
Michael Horst Free Picard Categories
Michael Lambert The Calculus of Fractions in a Cosmos of Internal Categories
JS Lemay Why FHilb is not an interesting differential category
Arthur J. Parzygnat and Benjamin P. Russo Non-commutative disintegration
Dorette Pronk and Laura Scull Conditions to Simplify the Bicategory of Fractions Construction
Amit Sharma Symmetric monoidal categories and Γ-categories
David I. Spivak Regular categories as double functors
Martin Szyld Sigma limits and applications
Remy Tuyeras Category theory for genetics
Felix Wellen, Egbert Rijke Abstract facts on formally étale maps
Mahmoud Zeinalian The rigidification functor and the fundamental group

Previous Meetings

  • 2017, CMU
  • 2015, University of Ottawa
  • 2012, Concordia
  • 2011, University of Ottawa
  • 2010, Dalhousie
  • 2009, CMU
  • 2008, Concordia
  • 2006, University of Ottawa
  • 2005, University of Ottawa
  • 2004, McGill University
  • 1999, McGill University
  • 1995, McGill University