It is sad that my Ada Lovelace post this year has to be for Maryam Mirzakhani. I never knew she was ill and had hoped to catch some impressive-named lectures from her in Stanford, sooner or later. I thought I had plenty of time. And Stanford has some pretty amazing lecture series asking for general audience kinds of talks. The woman was really impressive, it is a real shame to see her gone so young.
And yes this has been such a bad year for mathematicians, it feels spooky. Fred Linton and Vladimir Voevodsky (I need to read the long thread in the Coq mailing list) in September and Miles Tierney in October. But, personally for me, the hardest, Mike Gordon in August. So very sad!