An introduction to group theory (Minor error corrections below) 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: https://3b1b.co/monster-thanks Timestamps: 0:00 - The size of the monster 0:50 - What is a group? 7:06 - What is an abstract group? 13:27 - Classifying groups 18:31 - About the monster Errors: *Typo on the "hard problem" at 14:11, it should be a/(b+c) + b/(a+c) + c/(a+b) = 4 *Typo-turned-speako: The classification of quasithin groups is 1221 pages long, not 12,000. The full collection of papers proving the CFSG theorem do comprise tens of thousands of pages, but no one paper was quite that crazy. Thanks to Richard Borcherds for his helpful comments while putting this video together. He has a wonderful hidden gem of a channel: https://youtu.be/a9k_QmZbwX8 You may also enjoy this brief article giving an overview of this monster: http://www.ams.org/notices/200209/what-is.pdf If you want to learn more about group theory, check out the expository papers here: https://kconrad.math.uconn.edu/blurbs/ Videos with John Conway talking about the Monster: https://youtu.be/jsSeoGpiWsw https://youtu.be/lbN8EMcOH5o More on Noether's Theorem: https://youtu.be/CxlHLqJ9I0A https://youtu.be/04ERSb06dOg The symmetry ambigram was designed by Punya Mishra: https://punyamishra.com/2013/05/31/symmetry-new-ambigram/ The Monster image comes from the Noun Project, via Nicky Knicky This video is part of the #MegaFavNumbers project: https://www.youtube.com/playlist?list=PLar4u0v66vIodqt3KSZPsYyuULD5meoAo To join the gang, upload your own video on your own favorite number over 1,000,000 with the hashtag #MegaFavNumbers, and the word MegaFavNumbers in the title by September 2nd, 2020, and it'll be added to the playlist above. ------------------ These animations are largely made using manim, a scrappy open-source python library: https://github.com/3b1b/manim If you want to check it out, I feel compelled to warn you that it's not the most well-documented tool, and it has many other quirks you might expect in a library someone wrote with only their own use in mind. Music by Vincent Rubinetti. Download the music on Bandcamp: https://vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown Stream the music on Spotify: https://open.spotify.com/album/1dVyjwS8FBqXhRunaG5W5u If you want to contribute translated subtitles or to help review those that have already been made by others and need approval, you can click the gear icon in the video and go to subtitles/cc, then "add subtitles/cc". I really appreciate those who do this, as it helps make the lessons accessible to more people. ------------------ 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 on new videos, subscribe: http://3b1b.co/subscribe Various social media stuffs: Website: https://www.3blue1brown.com Twitter: https://twitter.com/3blue1brown Reddit: https://www.reddit.com/r/3blue1brown Instagram: https://www.instagram.com/3blue1brown_animations/ Patreon: https://patreon.com/3blue1brown Facebook: https://www.facebook.com/3blue1brown

Group of symmetries of a regular polygon. di-hedral in that you have to consider both rotations and reflections ⇒ if we’re considering _n_ sides, there are _2n_ members of the group. One for each possible rotation, reflection of said rotation, and identity.

In last last week's episode of PBS Infinite Series, we talked about different flavors of multiplication (like associativity and commutativity) to think about when multiplying things that aren't numbers. My examples of multiplying non-numbers were vectors and matrices, which come from the land of algebra. Today I'd like to highlight another example: We can multiply shapes!

Forming the set of equivalence classes is called “modding out” or “quotienting by” the equivalence relation.

Math is about more than just numbers. In this 'book' the language of math is visual, shown in shapes and patterns. This is a coloring book about group theory.