Home /  TGS: 3-manifold seminar: unknotting the figure eight knot

Seminar

TGS: 3-manifold seminar: unknotting the figure eight knot March 10, 2026 (09:40 AM PDT - 11:00 AM PDT)
Parent Program:
Location: Evans Hall, 939
Speaker(s) Qiuyu Ren (University of California, Berkeley)
Description No Description
Keywords and Mathematics Subject Classification (MSC)
Primary Mathematics Subject Classification No Primary AMS MSC
Secondary Mathematics Subject Classification No Secondary AMS MSC
Video
No Video Uploaded
Abstract/Media

This seminar series will take place on UC Berkeley campus, in Evans Hall room 939.

 

Using Gabai's results on sutured manifolds, Scharlemann and Thompson observed that if a knot has Seifert genus 1 and unknotting number 1, then it is a twist knot or a Whitehead double. Coward--Lackenby used this to prove that the figure 8 knot is the only genus 1 knot that admits more than one unknotting crossing change. We give an exposition on Scharlemann--Thompson's result, and discuss some proof(s) of Coward--Lackenby's theorem.

No Notes/Supplements Uploaded No Video Files Uploaded