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Talks in Sydney, August 2017

Sources: pensieve.

Nobody Solves the Quintic

Undergraduate Talk, August 17, 2017

Abstract. Everybody knows that nobody can solve the quintic. Indeed this insolubility is a well known hard theorem, the high point of a full-semester course on Galois theory, often taken in one's 3rd or 4th year of university mathematics. I'm not sure why so few know that the same theorem can be proven in about 15 minutes using *very* basic and easily understandable topology, accessible to practically anyone.


  1. The first week of any class on group theory.
  2. Knowing that every complex number other than $0$ has exactly $n$ roots of order $n$, and how to compute them.

Handout: Quintic-Handout.pdf. Slides: Quintic-Slides.nb. Talk video: .

Links: Demo Exp K17 kiw Ov talks TFD

Sources: pensieve.

The Dogma is Wrong

Algebra Seminar, August 18, 2017

Abstract. It has long been known that there are knot invariants associated to semi-simple Lie algebras, and there has long been a dogma as for how to extract them: "quantize and use representation theory". We present an alternative and better procedure: "centrally extend, approximate by solvable, and learn how to re-order exponentials in a universal enveloping algebra". While equivalent to the old invariants via a complicated process, our invariants are in practice stronger, faster to compute (poly-time vs. exp-time), and clearly carry topological information.

This is joint work with Roland van der Veen and continues work by Rozansky and Overbay.

Handout: Dogma.html, Dogma.pdf, Dogma.png.

Talk Video (in Toulouse).

The Dogma is Wrong - Extra Details

Sydney, August 21, 2017

Handout: pre-talk (pdf, nb), post-talk (pdf, nb).