An unsolved conjecture, and a clever topological solution to a similar question. Help fund future projects: https://www.patreon.com/3blue1brown An equally valuable form of support is to simply share some of the videos. Special thanks to these supporters: http://3b1b.co/topology-thanks Home page: https://www.3blue1brown.com/ This video is based on a proof from H. Vaughan, 1977. To learn more, take a look at this survey: https://pure.mpg.de/rest/items/item_3120610/component/file_3120611/content Thanks to these viewers for their contributions to translations Hebrew: Omer Tuchfeld ------------------ 3blue1brown is a channel about animating math, in all senses of the word animate. And you know the drill with YouTube, if you want to stay posted about new videos, subscribe, and click the bell to receive notifications (if you're into that). If you are new to this channel and want to see more, a good place to start is this playlist:    • Recommended   Various social media stuffs: Twitter: https://twitter.com/3Blue1Brown Facebook: https://www.facebook.com/3blue1brown/ Reddit: https://www.reddit.com/r/3Blue1Brown