This folder contains a formalization of various properties about sequential colimits. Most importantly, we prove that sigma-types commute with colimits. It accompanies a submitted paper by Kristina Sojakova, Floris van Doorn and Egbert Rijke.

This repository contains some unproven results, marked by `sorry`. No unproven results are used for any theorems discussed in the paper. You can write `print axioms theoremname` in a file to verify that `sorry` is not used in the proofs.

You will need a working version of Lean 2 to compile this repository. Installation instructions for Lean 2 can be found [here](https://github.com/leanprover/lean2). After that, you can run `linja` (or `path/to/lean2/bin/linja`) from the command-line in the main directory to compile this repository.