# What else can you do with solvable approximations?

### APA

Bar-Natan, D. (2018). What else can you do with solvable approximations? . Perimeter Institute. https://pirsa.org/18030082

### MLA

Bar-Natan, Dror. What else can you do with solvable approximations? . Perimeter Institute, Mar. 12, 2018, https://pirsa.org/18030082

### BibTex

@misc{ pirsa_18030082, doi = {}, url = {https://pirsa.org/18030082}, author = {Bar-Natan, Dror}, keywords = {Mathematical physics}, language = {en}, title = {What else can you do with solvable approximations? }, publisher = {Perimeter Institute}, year = {2018}, month = {mar}, note = {PIRSA:18030082 see, \url{https://pirsa.org}} }

## Abstract

Recently, Roland van der Veen and myself found that there are sequences of solvable Lie algebras "converging" to any given semi-simple Lie algebra (such as sl(2) or sl(3) or E8). Certain computations are much easier in solvable Lie algebras; in particular, using solvable approximations we can compute in polynomial time certain projections (originally discussed by Rozansky) of the knot invariants arising from the Chern-Simons-Witten topological quantum field theory. This provides us with the first strong knot invariants that are computable for truly large knots. But sl(2) and sl(3) and similar algebras occur in physics (and in mathematics) in many other places, beyond the Chern-Simons-Witten theory. Do solvable approximations have further applications?

This is a repeat of a talk I gave in McGill University in February, 2017. A video recording, a handout, and some further links are at McGill-1702