Homotopy Type Theory
Formalized Homotopy Theory

Here are some links to proofs about homotopy theory, formalized in homotopy type theory. Please add!

Maybe we could figure out a way not to duplicate stuff between this page and homotopy groups of spheres?

Ali: Results about homotopy groups of spheres should go there, everything else here.

Cast of characters so far: Jeremy Avigad, Guillaume Brunerie, Favonia, Eric Finster, Chris Kapulkin, Dan Licata, Peter Lumsdaine, Mike Shulman, Evan Cavallo

In progress


cohomology * To do cohomology with finite coefficients, all we need is the boring work of defining /p\mathbb{Z}/p\mathbb{Z} as an explicit group. * Calculate some more cohomology groups. * Compute the loop space of this construction and use it to define spectra.

At least one proof has been formalized

Whitehead’s theorem


Eilenberg-MacLane space * Dan’s construction. * K(G,n)K(G,n) is a spectrum, formalized


cohomology * Deriving cohomology theories from spectra * Mayer-Vietoris sequence, with exposition * Cohomology of the n-torus, which could be easily extended to any finite product of spheres.

Freudenthal Suspension Theorem

Freudenthal suspension theorem? Implies π k(S n)=π k+1(S n+1)\pi_k(S^n) = \pi_{k+1}(S^{n+1}) whenever k2n2k \leq 2n - 2

Homotopy limits

Van Kampen

van Kampen theorem * Mike’s proofs are in the book and Favonia formalized it. {{deadlink}}

Covering spaces

Covering space? * Favonia’s proofs (link in flux due to library rewrite).


Blakers-Massey theorem?

category: homotopy theory