Date started: September 2019
Leads: Arnaud Chéritat
Abstract
How to model a smooth Alexander horned sphere (except at the tips)? At the first conference during the ICERM semester “Illustrating mathematics”, I contributed a few questions on the board on the list of “mathematical things you would like to see illustrated in geometry”. Among them I asked for the following: “make a model of Alexander’s horned sphere that is smooth (except at the tips)”. A participant approached me a few days later: it was Pr Robert Edwards from UCLA. He drew for me a sketch, of which the photo is below. In November I started to work on making a 3D mesh on this principle, which I 3D-printed with the help of Alba Malaga and Samuel Lelièvre. Greg McShane also has a design, we will try it later.
Media
![](https://i0.wp.com/im.icerm.brown.edu/wp-content/uploads/2019/12/image5-2.png?resize=1091%2C818&ssl=1)
![](https://i0.wp.com/im.icerm.brown.edu/wp-content/uploads/2019/12/image1-5.png?resize=1091%2C2182&ssl=1)
![](https://i0.wp.com/im.icerm.brown.edu/wp-content/uploads/2019/12/image6-3.png?resize=1014%2C676&ssl=1)
![](https://i0.wp.com/im.icerm.brown.edu/wp-content/uploads/2019/12/image2-8.png?resize=1091%2C899&ssl=1)
![](https://i0.wp.com/im.icerm.brown.edu/wp-content/uploads/2019/12/image3-3.png?resize=1091%2C1358&ssl=1)
![](https://i0.wp.com/im.icerm.brown.edu/wp-content/uploads/2019/12/image4-6.jpg?resize=1091%2C1153&ssl=1)