The Moessner Miracle. Why wasn’t this discovered for over 2000 years?

Today’s video is about a mathematical gem that was discovered 70 years ago. Although it’s been around for quite a while and it’s super cool and it’s super accessible, hardly anybody knows about it. 00:00​ Intro 04:58 Chapter 1: Making our own proof 09:55​ Chapter 2: Some more amazing facts 13:11​ Chapter 3: Post’s proof 23:36​ Supporters If after watching this video you’d like to find out more about Moessner’s result, the following PhD thesis features a very comprehensive bibliography: The proof by Karel Post that I matholologerise in the second half of this video is contained in this paper: Karel A. Post. Moessnerian theorems. How to prove them by simple graph theoretical inspection. Elemente der Mathematik, (2):46–51, 1990. Post also proves a couple of generalisations of Moessner’s theorem. Another good write-up of the same proof can be found in Ross Honsberger“s 1991 book More Mathematical Morsels. Honsberger says about Moessner that “he was internationally k