# Online: Seminar, Anton Alekseev (University of Geneva), Conjugation of Words, Self-Intersections of Planar Curves, and Non-Commutative Divergence #### calendar\_today Date and Time **April 6, 2021** 10:00AM - 10:00AM EDT #### pin\_drop Location **Zoom** ![Alekseev](/sites/g/files/omnuum6611/files/styles/hwp_1_1__960x960_scale/public/mathpicture/files/screenshot_at_2021-03-18_14-30-19.png?itok=-uyl2gNL) **Location:** Zoom **Time:** Tuesday, April 6, 2021, 10:00 AM (Eastern US), 15:00 (UK/Eire), 16:00 (Central Europe), 22:00 (China) **Title:** Conjugation of Words, Self-Intersections of Planar Curves, and Non-Commutative Divergence **Abstract:** The space spanned by homotopy classes of free oriented loops on a 2-manifold carries an interesting algebraic structure (a Lie bialgebra structure) due to Goldman and Turaev. This structure is defined in terms of intersections and self-intersections of planar curves. In the talk, we will explain a surprising link between the Gaoldman-Turaev theory and the Kashiwara-Vergne problem on properties of the Baker-Campbell-Hausdorff series. Important tools in establishing this link are the non-commutative divergence cocycle and a novel characterisation of conjugacy classes in free Lie algebras in terms of cyclic words. The talk is based on joint works with N. Kawazumi, Y. Kuno and F. Naef. **Additional Ways to Join** Join by telephone (use any number to dial in) +1 929 436 2866 +1 312 626 6799 +1 669 900 6833 400 669 9381 China Toll-free International numbers available: [https://harvar](https://harvard.zoom.us/u/aclg6kOggb)[d.zoom.us/u/aclg6kOggb](https://harvard.zoom.us/u/aclg6kOggb) One tap mobile: +19294362866,,779283357# US (New York) Join by SIP conference room system Meeting ID: 779 283 357 <779283357@zoomcrc.com> **Attachments** --- Attachments- [ picture\_as\_pdf Flyer.pdf ](/sites/g/files/omnuum6611/files/mathpicture/files/alekseev_seminar_apr_6_2021.pdf) --- Share on:- [ Facebook ](#) - [ Twitter ](#) - [ Linkedin ](#) Save: [ Add to calendar calendar\_today ](https://mathpicture.fas.harvard.edu/node/1584448/event-feed.ics) Copy link link