9th December

On this day in 1911 Henri Poincaré wrote the editor of a mathematical journal to ask if, contrary to custom, an unfinished piece of work could be published. He explained that at his age he might not be able to finish it, but that his work might provide ideas for another. The paper was published and not long afterwards George Birkhoff completed the solution. Poincaré died the following year.

On this day in 2013 Google released a Hopper doodle