The Dehn Invariant

It was #3 on Hilbert's list of the most important problems in mathematics - until his student solved it. More links & stuff in full description below ↓↓↓ Featuring Daniel Litt, currently at the Institute for Advanced Study - https://twitter.com/littmath David Hilbert's problems: https://en.wikipedia.org/wiki/Hilbert%27s_problems Max Dehn's famed proof: https://archive.org/details/mathematischean33behngoog/page/n488 Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science.

Additional information

It was #3 on Hilbert's list of the most important problems in mathematics - until his student solved it.

Featuring Daniel Litt, currently at the Institute for Advanced Study - https://twitter.com/littmath

David Hilbert's problems: https://en.wikipedia.org/wiki/Hilbert%27s_problems

Max Dehn's famed proof: https://archive.org/details/mathematischean33behngoog/page/n488