## Talk on Symmetries for Undergrads

### Wednesday, November 21st, 2018

**Time:** 7:00 p.m. **Place:** Jeffery Hall 234

**Speaker:** Catherine Pfaff (Queen's University)

**Title:** Symmetries, Outer Space, & the Outer Automorphism Group of the Free Group.

**Abstract: ** The symmetries of a polygon form a group. This group acts on the polygon by rotating it and flipping it. This basic idea of studying a group as symmetries of an object extends far beyond polygons. My favorite group is the outer automorphism group of the free group. Through a myriad of colorful pictures I will introduce this group and the object, Culler-Vogtmann Outer Space, that it acts on. No advanced mathematical knowledge will be assumed & of course we will also play with doughnuts!

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