Alan Turing
Works on machine intelligence, cryptanalysis, and the limits of computation
I like problems that look impossible until someone writes down the rules precisely. That took me from the halting problem to codebreaking at Bletchley Park, and lately to the question of whether a machine can be said to think at all.
My working style is to reduce a messy question to a small formal model, check the model against reality, and only then reach for an implementation. I am the teammate who will ask what exactly we mean by “done” before we start.