## Örn Arnaldsson (06/06/17)

PhD thesis defense rehearsal

### Speaker: Örn Arnaldsson, University of Minnesota

### Title: Involutive moving frames

Location: Tg-227 (Tæknigarður, 2. hæð)

Time: Tuesday 6 June at 10:50

### Abstract:

Cartan’s equivalence method and the method of the equivariant moving frames are the two best known methods for solving equivalence problems in differential geometry, differential equations, calculus of variations and control theory. My thesis demonstrates how the two methods are really two sides of the same coin and combines them in a powerful hybrid method that increases the computational efficiency of both of its progenitors. This novel viewpoint provides effortless proofs to some previously hard-to-prove results, such as the Lie-Tresse theorem. Furthermore, we obtain proof of a long standing conjecture of Cartan on the termination of his equivalence method.