2025-12-11: Noam Zeilberger (Laboratoire d'informatique de l'École Polytechnique)

Fri, 5 Dec 2025 17:58:41 +0000

Noam Zeilberger (Laboratoire d'informatique de l'École Polytechnique)

The free bifibration on a functor

Abstract

Joint work with Bryce Clarke and Gabriel Scherer.

Preprint: https://arxiv.org/abs/2511.07314

A functor p : D → C is a bifibration if, loosely speaking, one can push and pull objects of D along arrows of C. The talk will begin by recalling the formal definition together with some motivation, and then explain how the free bifibration generated by a functor p may be constructed using a simple sequent calculus. This sequent calculus is closely related to a certain "zigzag double category" ℤC constructed as the free bifibration on the identity functor id : C → C, and which is also the free fibrant double category on C. The double category perspective leads to a nice string diagram calculus, while proof-theoretic techniques allow us to derive a canonicity result for free bifibrations, and to analyze some examples of a combinatorial nature.

2025-12-11 15:00:00 UTC
LT310 and online